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Resetting the late timing of ‘night owls’ has a positive impact on mental health and performance
Abstract
Background:
There is conflict between living according to our endogenous biological rhythms and our external environment, with disruptions resulting in negative consequences to health and performance. This is often documented in shift work and jet lag, but 'societal norms' (eg, typical working hours) can create profound issues for 'night owls', people whose internal biological timing predisposes them to follow an unusually late sleep-wake cycle. Night owls have also been associated with health issues, mood disturbances, poorer performance and increased mortality rates.
Methods:
This study used a randomized control trial design aimed to shift the late timing of night owls to an earlier time (phase advance), using non-pharmacological, practical interventions in a real-world setting. These interventions targeted light exposure (through earlier wake up/sleep times), fixed meals times, caffeine intake and exercise.
Results:
Overall, participants demonstrated a significant advance of ∼2 h in sleep/wake timings as measured by actigraphy and circadian phase markers (dim light melatonin onset and peak time of the cortisol awakening response), whilst having no adverse effect on sleep duration. Notably, the phase advance was accompanied by significant improvements to self-reported depression and stress, as well as improved cognitive (reaction time) and physical (grip strength) performance measures during the typical 'suboptimal' morning hours.
Conclusions:
Our findings propose a novel strategy for shifting clock timing towards a pattern that is more aligned to societal demands that could significantly improve elements of performance, mental health and sleep timing in the real world.
... The high prevalence of poor mental health in elite athlete populations highlights the critical need for further research and evidence-based interventions (Reardon et al., 2019). Environmental factors that influence mental health include exercise, light, and social cues (Facer-Childs et al., 2019;Haynes et al., 2016). These same exposures influence sleep and circadian health, which compound the strain on mental health (Foster, 2020). ...
... Later exposure of exercise and light can increase evening activation and delay circadian rhythms(Facer-Childs et al., 2019;Haynes et al., 2016). The post hoc analyses demonstrated that the female athletes spent less time inactive and less time in dim light in the 3-h prior to sleep. ...
Elite athletes are vulnerable to sleep and circadian disruption and associated mental health symptoms. This study aimed to investigate sex differences in sleep, circadian rhythms, and mental health, as well as the moderating role of sex in the prediction of mental health, among male professional and female semi-professional elite athletes. Participants were 87 elite Australian Rules football (ARF) athletes (43% female; mean [standard deviation] age 24.0 [4.1] years). Participants completed baseline questionnaires, 2 weeks of sleep/wake monitoring via actigraphy, and a circadian phase assessment (dim-light melatonin onset [DLMO]). Cross-sectional data were collected in training-only Australian Football League (AFL) Men's and Women's pre-season periods, with 53 providing data in two pre-seasons. Female athletes, relative to males, reported poorer mental health (a higher athlete psychological strain score), had a later mid-sleep time (by 28 min), reported a greater preference towards eveningness, and displayed a later circadian phase (by 33 min). For female athletes, lower sleep efficiency and lower sleep regularity were associated with poorer mental health. For female athletes, there were U-shaped relationships between both morningness–eveningness and phase angle (interval between sleep onset and DLMO time) and mental health. No significant relationships were found for male athletes. In summary, elite female ARF athletes reported poorer mental health, relative to males, especially when experiencing sleep or circadian disruption. Lifestyle factors associated with sex differences in ARF professionalism (scheduling, finances, supports) may contribute to these findings. Programmes to improve sleep, circadian alignment, and mental health among female semi-professional elite athletes should be strongly considered.
... The circadian rhythm not only dictates when we sleep or wake up, but also significantly contributes to, for example, our dips and peaks of alertness throughout a day (Abdullah et al. 2014). Prior studies found associations between circadian rhythms and health, both physically (Cho 2001) and mentally (Biss and Hasher 2012;Kreitzman and Foster 2011;Facer-Childs et al. 2019). For example, 'morning larks' were found to be higher in positive affect than those who woke up late (Biss and Hasher 2012). ...
... For example, 'morning larks' were found to be higher in positive affect than those who woke up late (Biss and Hasher 2012). Researchers reset the undesirable late timing of 'night owls' in a study and consequently observed a positive impact on cognitive performance and mental health (Facer-Childs et al. 2019). Furthermore, a positive but weak association between morning alertness and sleep quality was reported in (Reid, Maldonado, and Baker 2002), suggesting that, if people sleep well at night, they tend to have higher alertness levels the next day. ...
Circadian rhythm has been linked to both physical and mental health at an individual level in prior research. Such a link at population level has been long hypothesized but has never been tested, largely because of lack of data. To partly fix this literature gap, we need: a dataset on population-level circadian rhythms, a dataset on population-level health conditions, and strong associations between these two partly independent sets. Recent work has shown that affect on social media data relates to population-level circadian rhythms. Building upon that work, we extracted five circadian rhythm metrics from 6M Reddit posts across 18 major cities (for which the number of residents is highly correlated with the number of users), and paired them with three ground-truth health metrics (daily number of steps, sleep quantity, and sleep quality) extracted from 233K wearable users in these cities. We found that rhythms of online activity approximated sleeping patterns rather than, what the literature previously hypothesized, alertness levels. Despite that, we found that these rhythms, when computed in two specific times of the day (i.e., late at night and early morning), were still predictive of the three ground-truth health metrics: in general, healthier cities had morning spikes on social media, night dips, and expressions of positive affect. These results suggest that circadian rhythms on social media, if taken at two specific times of the day and operationalized with literature-driven metrics, can approximate the temporal evolution of people's shared underlying biological rhythm as it relates to physical activity (R2=0.492), sleep quantity (R2=0.765), and sleep quality (R2=0.624).
... This can be seen in the developmental shift toward eveningness during adolescence, which has been related to higher negative moods and lower well-being (Díaz-Morales, Escribano, & Jankowski, 2015). Moreover, in laboratory conditions, earlier shift in sleep-timing was found to lead to a decrease in depression and stress and improvement in the well-being of evening-types (Facer-Childs, Middleton, Skene, & Bagshaw, 2019). Similarly, an earlier shift in depressive patients has been reported to improve mood states (Zaki et al., 2017). ...
... The results showed that earlier shift in sleeptiming was related to better mood and well-being. This has been shown earlier in the general population (Facer-Childs et al., 2019;Hasler, Buysse, & Germain, 2015) and in depressive patients (Zaki et al., 2017). Contrastingly, a shift toward eveningness during adolescence has been related to higher negative moods and lower well-being (Díaz-Morales et al., 2015). ...
It is suggested that social obligations, such as early work/school starts, have a disadvantageous impact on sleep behavior that can further transfer to mental health problems. Lockdown as a result of the COVID-19 pandemic created a unique opportunity to research human sleep-wake behavior in naturalistic conditions of decreased social obligations. This study aimed to test whether a change in habitual sleep-wake timing (shift in chronotype) during the COVID-19 lockdown impacted mood and well-being, and whether the impact differs according to morningness-eveningness preference. University students (N = 1011; Meanage = 21.95 ± 1.95 years) filled out self-report questionnaires containing measures of chronotype (midpoint of sleep) before and during the COVID-19 lockdown, morningness-eveningness preference, mood, and well-being. The impact of morningness-eveningness preference and shift in chronotype was tested via multiple regression analyses. Results showed that participants shifted their chronotype in line with their morningness-eveningness preference, and that shift toward earlier sleep-wake timing was related to better moods and well-being. Moreover, higher levels of positive mood (vigor) and well-being were found in individuals who shifted their sleep-wake timing earlier and were higher on morningness.
... 29,30 The experimental advance shift of evening-type late timing with light exposure, behavioral measures and exercise leads to significant improvement in selfreported depression. 31 Such modulation of brain physiology by circadian rhythms was recently shown to be underpinned by changes in cortical excitability, which is enhanced and associated with improved cognitive performance at the preferred time of the day. 32 Interestingly, impaired cortical excitability and brain plasticity have also been reported in depression. ...
... The population consisted of 77% women, of median (IQR) age 39 (30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48) years. Two-thirds of participants were employees with daytime working hours before the confinement and worked from home during the lockdown. ...
Purpose
The containment of the population during the COVID-19 pandemic led to the emergence or recurrence of psychiatric conditions and sleep disorders. The influence of sleep/wake rhythm on mental health is well known. The objective of our study was to evaluate the link between the shift in sleep/wake rhythm and the presence of depressive symptoms during the March to May 2020 lockdown in the French population.
Participants and Methods
Participants (n = 2513) were recruited via newspapers and social networks in March 2020. We evaluated i) the chronotype before and during the lockdown, assessed by the change in mid-sleep time on work-free days corrected for sleep debt on workdays (delta MSFsc); ii) morningness-eveningness circadian preference (Horne & Ostberg questionnaire); iii) depressive symptoms (Patient Health Questionnaire-9, PHQ-9). The delta MSFsc and the PHQ-9 score were compared between circadian preference types. A multivariate model adjusted for age, sex, circadian preference, housing type, and marital status was used to assess the influence of delta MSFsc on the PHQ-9 score in the whole population.
Results
The population consisted of 77% women, of median (IQR) age 39 (30–48) years. Compared with the pre-lockdown period, the median (IQR) MSFsc was shifted by 30 (0–66) min during the lockdown, with a significant difference between evening [60 (15–120) min], morning [15 (0–46) min] and neutral [30 (0–70) min] circadian type individuals, p < 0.001. One-third of all participants had moderate to severe depressive symptoms (PHQ-9 ≥ 10). A 1-hour shift in MSFsc was associated with a 0.50-point increase [95% CI (0.28; 0.72), p < 0.001] in the PHQ-9.
Conclusion
A phase delay in the chronotype was observed in the general population during lockdown. Such disruption was associated with depressive symptoms but the direction of the relationship remains hypothetical. The impact on mental health of preventive measures targeting the sleep/wake rhythm in this context needs further evaluation.
... 29,30 The experimental advance shift of evening-type late timing with light exposure, behavioral measures and exercise leads to significant improvement in selfreported depression. 31 Such modulation of brain physiology by circadian rhythms was recently shown to be underpinned by changes in cortical excitability, which is enhanced and associated with improved cognitive performance at the preferred time of the day. 32 Interestingly, impaired cortical excitability and brain plasticity have also been reported in depression. ...
... The population consisted of 77% women, of median (IQR) age 39 (30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48) years. Two-thirds of participants were employees with daytime working hours before the confinement and worked from home during the lockdown. ...
Juliette Felician,1– 3 Filipe Galvao,3 Mylène Lefebvre,3 Mikail Nourredine,2,4– 6,* Laure Peter-Derex1,2,7,* 1Centre for Sleep Medicine and Respiratory Diseases, Hôpital de la Croix-Rousse, Hospices Civils de Lyon, Lyon, France; 2Medicine faculty, Lyon 1 University, Lyon, France; 3Unité Michel Jouvet – Pôle Est – Z19, Centre Hospitalier Le Vinatier, Bron, France; 4Biostatistics Unit, University Hospital Service of Pharmacotoxicology and Public Health Department, Hospices Civils de Lyon, Lyon, France; 5Research Department, Centre Hospitalier Le Vinatier, Bron, France; 6Biometry and Evolutionary Biology Laboratory, UMR CNRS 5558, Lyon, France; 7Lyon Neuroscience Research Centre, CNRS UMR 5292/INSERM U1028, Lyon, France*These authors contributed equally to this workCorrespondence: Laure Peter-Derex, Centre for Sleep Medicine and Respiratory Diseases, Hôpital de la Croix-Rousse, Hospices Civils de Lyon, 103 Grande Rue de la Croix-Rousse, Lyon, 69004, France, Tel +33 4 72 07 17 69, Fax +33 4 72 07 28 08, Email laure.peter-derex@chu-lyon.frPurpose: The containment of the population during the COVID-19 pandemic led to the emergence or recurrence of psychiatric conditions and sleep disorders. The influence of sleep/wake rhythm on mental health is well known. The objective of our study was to evaluate the link between the shift in sleep/wake rhythm and the presence of depressive symptoms during the March to May 2020 lockdown in the French population.Participants and Methods: Participants (n = 2513) were recruited via newspapers and social networks in March 2020. We evaluated i) the chronotype before and during the lockdown, assessed by the change in mid-sleep time on work-free days corrected for sleep debt on workdays (delta MSFsc); ii) morningness-eveningness circadian preference (Horne & Ostberg questionnaire); iii) depressive symptoms (Patient Health Questionnaire-9, PHQ-9). The delta MSFsc and the PHQ-9 score were compared between circadian preference types. A multivariate model adjusted for age, sex, circadian preference, housing type, and marital status was used to assess the influence of delta MSFsc on the PHQ-9 score in the whole population.Results: The population consisted of 77% women, of median (IQR) age 39 (30– 48) years. Compared with the pre-lockdown period, the median (IQR) MSFsc was shifted by 30 (0– 66) min during the lockdown, with a significant difference between evening [60 (15– 120) min], morning [15 (0– 46) min] and neutral [30 (0– 70) min] circadian type individuals, p < 0.001. One-third of all participants had moderate to severe depressive symptoms (PHQ-9 ≥ 10). A 1-hour shift in MSFsc was associated with a 0.50-point increase [95% CI (0.28; 0.72), p < 0.001] in the PHQ-9.Conclusion: A phase delay in the chronotype was observed in the general population during lockdown. Such disruption was associated with depressive symptoms but the direction of the relationship remains hypothetical. The impact on mental health of preventive measures targeting the sleep/wake rhythm in this context needs further evaluation.Keywords: phase delay, pandemic, containment, mental health, chronotype, circadian preference
... Besides the amount of time spent sleeping, the timing of sleep also has an effect on health. For example, people with later chronotypes, meaning that they have a preference for later bedtimes and wake times, have a higher risk of health problems, such as metabolic dysfunction, cardiovascular disease (CVD), and mental health concerns as well as a higher risk of both morbidity and mortality due to these causes [6][7][8][9]. Long sleep latency, or the amount of time it takes to fall asleep, is a marker of overall lower sleep quality and potential underlying sleep disorder (i.e., insomnia) [10,11]. ...
Background/Objectives: This study aimed to examine associations between meal timing habits and sleep health in midlife Mexican women. Methods: Data comprised 379 midlife Mexican women who participated in a phone survey conducted within the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) project during the early stages of the COVID-19 pandemic. Women answered questions related to meal habits and sleep duration, latency, and quality. We used linear regression to investigate the associations between meal timing, frequency of meals/snacks, eating window (duration between first and last eating occasion of the day), duration between last meal, bedtime, sleep duration, and logistic regression to examine the associations between meal timing, sleep latency, and sleep quality, adjusting for confounders. Results: Later timing of meals throughout the day, and a shorter interval between the last meal of the day and bedtime, were associated with prolonged sleep latency and worse sleep quality. Associations with sleep duration were mixed: a longer eating window and a later largest and last meal were each associated with shorter sleep duration, while a later first meal and a shorter interval between the last meal of the day and bedtime were associated with longer sleep duration. Conclusions: Meal timing habits are associated with sleep duration, latency, and quality in midlife women.
... With regards to the cortisol rhythm, one study in 23 adult men found that sleep restriction (five nights of 4 hours) significantly delayed the peak of cortisol secretion by 16 minutes (Van Leeuwen et al., 2010). A twoweek sleep hygiene intervention in 22 adults with a delayed rhythm showed that advancing sleep and meal times by 2 hours similarly advanced the melatonin and cortisol rhythm (Facer-Childs et al., 2019). ...
Background: ADHD is highly comorbid with Delayed Sleep Phase Syndrome (DSPS). Both are associated with obesity and diabetes, which can be caused by long-term dysregulations of appetite and glucose metabolism. This study explores hormones involved in these processes and the effects of chronotherapeutic interventions in a small sample of adults with ADHD and DSPS. Methods: Exploratory, secondary analysis of data from the PhASE study, a three-armed randomized clinical trial, are presented, including 37 adults (18–53 years) with ADHD and DSPS receiving three weeks of 0.5 mg/day (1) placebo, (2) melatonin, or (3) melatonin plus 30 minutes of bright light therapy (BLT). Leptin (appetite-suppressing), ghrelin (appetite-stimulating), insulin, insulin-like growth factor-1 (IGF-1), and glucose were measured from blood collected at 08:00 hours. Salivary cortisol was collected during the first 30 minutes after awakening and self-reported appetite was assessed. Results: Baseline leptin and IGF-1 levels were higher than reference ranges, and ghrelin and cortisol levels were lower, while insulin and glucose were normal. Melatonin treatment decreased leptin and insulin. Other outcomes remained unchanged and melatonin + BLT had no effects. Conclusion: Due to the small sample size and exploratory nature of the study, results should be interpreted with caution. Overall, these results show no strong indications for dysregulation of appetite and glucose metabolism to suggest high risk of obesity and diabetes in this small sample of adults with ADHD and DSPS. However, baseline appetite was suppressed, likely because measurements took place in the early morning which could be considered the biological night for this study population. Melatonin treatment seemed to cause subtle changes in appetite-regulating hormones suggesting increased appetite. Chronotherapeutic treatment may affect appetite-regulating hormones by advancing the biological rhythm and/or altering eating behaviors, but this remains to be investigated in larger samples using detailed food diaries.
... Not only that the present findings are consistent with prior findings, but the present results also suggested that an early intervention should be implemented to reset the rest-activity pattern in those experiencing delayed sleep patterns to prevent this trend running its course and thereby lowering risks of developing depression. Indeed, a randomized clinical trial has already found that doing this has a positive impact (34). Moreover, Cruz-Sanabria et al. (35) showed that exogenous melatonin on sleep and circadian parameters had a significant effect on bipolar disorder (BD) and delayed sleep-wake phase disorder patients (DSWPD). ...
Objective
To test the psychometric properties of the Chinese version of the biological rhythms interview of assessment in neuropsychiatry (C-BRIAN) in a group of young adults with and without depressive symptoms.
Methods
Three hundred and seventy-eight university students were recruited as participants. Based on the scores from Center for Epidemiological Survey Depression Scale (CES-D), students were divided into the depressed group and healthy group. Explorative factor analysis was applied to assess the construct validity of the C-BRIAN. The Pittsburgh Sleep Quality Index (PSQI) and CES-D were compared with the C-BRIAN to test the convergent validity. The internal consistency of the C-BRIAN was also examined.
Results
Three factors were extracted (activities, eating patterns, and sleep factors) explaining 63.9% of the total variance. The internal consistencies were very good with a coefficient of 0.94 (overall) and 0.89–0.91 for three factors. The domains of activities, eating patterns, and sleep were moderately correlated with PSQI (r=0.579) and CES-D (r=0.559) (ps<0.01).
Conclusion
Our findings suggest that C-BRIAN has good validity and reliability which can be used to assess the biological rhythm in the young adult population with depressive symptoms. C-BRIAN would be a reliable tool to detect depressive symptoms for timely prevention and intervention in the community.
... This negative behavior must be introduced to children or adolescents from an early age to prevent this behavior (Salmivalli et al., 2021). Negative behavior can be changed into positive behavior that can be carried out by students or adolescents at school (Facer-Childs et al., 2019). These forms of positive behavior include always maintaining health by exercising in the morning at school, having a nutritious breakfast, enjoyable learning activities, socializing with peers, participating in school activities such as extracurriculars, and asking for first aid for physical or mental problems at school (Dodok et al. al., 2022). ...
Mental health is one of the negative behaviors in teenagers such as bullying. Bullying can cause teenagers to become anxious, depressed, sleep disorders, angry, and at risk of suicide. To find out this, developing an instrument for positive adolescent behavior in preventing bullying is necessary. This research aims to test the validity and reliability of the questionnaire. Questionnaire Positive Behavior Support Quality of Life Questionnaire (PBSQLQ) in Indonesian. The method used is testing a questionnaire PBSQLQ in Indonesian with a quantitative approach and cross-sectional design. The sample was 30 teenagers living in Malang Regency using an incidental sampling technique. PBSQLQ results in Indonesian have five indicators, namely health and safety (Cronbach alpha = 0.961), self-advocacy (Cronbach alpha = 0.831), social relationships (Cronbach alpha = 0.852), productive activities (Cronbach alpha = 0.741), and community participation (Cronbach alpha = 0.755). The validity test results of all indicator questions were declared valid. Analysis of questionnaires about positive behavior in preventing bullying in teenagers using PBSQLQ in Indonesian can be used as a measuring tool for mental health research in teenagers due to bullying. So, this questionnaire can be used as an indicator of the positive behavior of teenagers in preventing bullying, especially on the impact on mental health in teenagers. This research concludes that the PBSQLQ in Indonesian has a valid value for each question per indicator and has a reliable or consistent value as a tool for measuring positive behavior in preventing bullying in teenagers.
... Extreme chronotypes have been linked to circadian misalignment (Gentry et al. 2021), which increases the risk for neurologic, psychiatric, cardiometabolic, and immune disorders (Fishbein et al. 2021). E-types often exhibit symptoms similar to Delayed Sleep-Wake Phase Disorder, such as higher depression scores, decreased morning cognitive performance, and excessive daytime sleepiness (Facer-Childs et al. 2019). Chronotypes can also impact cardiac structure and function. ...
Purpose
Whether chronotype affects the health outcomes of night shift work populations is unknown. This study aimed to assess the influence of different chronotypes in the rotating night shift population on sleep status, mood, blood pressure (BP), and heart rate variability (HRV), as well as the circadian rhythm of BP and HRV.
Methods
A total of 208 rotating night shift workers were included. All participants completed structured questionnaires to assess chronotype, mood and sleep status. During their daily lives outside of the night shift, they underwent 24-hour Holter electrocardiogram monitoring and 24-hour ambulatory blood pressure monitoring. Day-time and night-time BP and BP dipping were obtained. Day-time and night-time HRV values (SDNN, RMSSD, LF, HF, LF nu, SD1, SD2 and SD2/SD1) were calculated and fitted to the cosine period curve. Three circandian parameters (mesor, amplitude and acrophase) were extracted to quantify the circadian rhythm of the HRV indices.
Results
Among all three groups, E-type showed more fatigue and sleepiness. In addition, E-type showed blunted diastolic BP dipping. Notably, E-type showed association with higher RMSSD, LF, HF and SD1 in the night time, and higher mesors of RMSSD and LF and amplitude of SD2/SD1 in circadian analysis.
Conclusion
Chronotype is a factor affecting fatigue, sleepiness and cardiovascular circadian rhythms of rotating night shift workers. Chronotype should be taken into consideration for managing night-shift rotation to promote occupational health.
... In line with earlier studies (Merikanto & Partonen, 2020;Wittmann et al., 2006), stable Evening-types reported more insufficient sleep and more discrepancy in the stability of weekly sleep-wake rhythms as evidenced by sleeping longer on free days than on workdays across the 10-year period. Since insufficient sleep and social jet lag among Evening-types accumulate during workdays in particular (Merikanto & Partonen, 2020;Roenneberg et al., 2019;Wittmann et al., 2006), there is a higher risk of mismatch between the innate sleep need and timing and the actualized rhythms among Eveningtypes that could be corrected by better aligning (Facer-Childs et al., 2019). Our findings also indicate that shifts toward Eveningness increase the odds for discrepancy in sleep duration between workdays and free days. ...
Objetivo: Generalmente se observa un cambio hacia la Vespertinidad en el comportamiento circadiano de sueño-vigilia desde la niñez hasta la adolescencia, pero se sabe menos sobre los cambios circadianos durante la edad adulta. Los cambios circadianos durante la mediana edad son de gran interés, ya que la Vespertinidad se asocia con una variedad de problemas relacionados con la salud, incluidos síntomas psicológicos y trastornos mentales. En este estudio, examinamos la estabilidad circadiana a lo largo de diez años, de 42 a 52 años de edad, y cómo se asoció con el sueño y la salud mental en un seguimiento de cohorte de la población general finlandesa (n = 976). Métodos: El tipo circadiano se evaluó en ambas edades con un ítem ampliamente utilizado para la autoestimación de Matutinidad/Vespertinidad del cuestionario original de Horne-Östberg de Matutininidad-Vespertinidad. Se utilizaron ecuaciones de estimación generalizadas para analizar cómo un cambio en la Matutinidad/Vespertinidad se asociaba longitudinalmente con el sueño y la salud mental. Resultados: Nuestros hallazgos indican que el tipo circadiano es un rasgo muy estable durante la mediana edad, con cambios principalmente moderados en el 42.2% de los adultos y ningún cambio circadiano en el 57.8% de los adultos. La mayoría de los cambios ocurrieron dentro del mismo tipo circadiano (23.9%), en segundo lugar después de los cambios entre tipos circadianos moderados (13.3%). Los cambios entre los tipos Definitivos Vespertinos y Matutinos fueron muy raros (0.5%). Los del tipo Vespertino estable informaron más falta de sueño, discrepancia entre la duración del sueño en los días laborables y libres, y depresión en comparación con los del tipo Matutino estable. Los cambios moderados hacia la Matutinidad, que comprenden principalmente aquellos dentro del tipo Matutino, se asociaron con una reducción de angustia y síntomas psicológicos. Conclusiones: En conclusión, nuestros hallazgos muestran una alta estabilidad del tipo circadiano de la edad adulta media. Sin embargo, los cambios hacia la Matutinidad parecen estar asociados con una mejor salud mental.
... Bold indicates statistically significant differences of p-values.TA B L E 6Comparison of each variable between TMDs and the TMD-free group.F I G U R E 4 Chronotype profile distribution of the TMDs and non-TMD groups.on the pathogenesis of TMDs. At the same time, since TMDs can be prevented and alleviated by changing bad habits(Agha-Hosseini et al., 2017), this study suggests that doctors and dentists may consider changing patients' chronotype profiles as a potential preventative or treatment strategy for TMD symptoms(Facer-Childs et al., 2019;Schulte & Riemersma-van der Lek, 2021). In addition, the larger sample size and more abundant sample sources in this study are significant advantages that cannot be ignored.Nonetheless, there were several limitations to this study. ...
Background
Temporomandibular joint disorders (TMDs) are common in young adults, and the link between chronotype profile and TMDs is unclear.
Objective
This study examined TMD prevalence and chronotype distribution and explored the relationship between chronotype and TMDs in young adults.
Materials and Methods
A total of 663 students from Sichuan University completed questionnaires. Chronotype profiles were assessed using the Morningness‐Eveningness Questionnaire, and TMDs were screened using the Fonseca Memory Index. To validate the findings, 68 TMD patients and 136 controls were enrolled.
Results
The prevalence of TMDs was 69.7%, with significant differences among chronotype profiles. The intermediate profile was the most common chronotype. Eveningness profile was associated with higher TMDs prevalence and severity. Muscle pain and side movement difficulty scores were higher in eveningness and intermediate profiles. Female gender (OR 2.345; 95% CI 1.668–3.297) was a TMD risk factor, while morningness profile (OR 0.537; 95% CI 0.297–0.970) was protective. Validation with TMD patients and controls supported these findings, showing higher eveningness profile prevalence in the TMD groups.
Conclusions
TMDs have a high prevalence in college students, chronotype profiles shown to be associated with TMDs. Morningness is the protection factor in TMDs and PT, eveningness is a risk factor for IT.
... В результате группы мышей, подвергшиеся воздействию ALAN, показали более низкие результаты в тестах предпочтения сахарозы (р<0,0001 для самок и р<0,001 для самцов), наблюдалось снижение потребления жидкости у самок (р<0,008), а также более низкие результаты в тестах принудительного плаванья. Такие данные демонстрируют повышенное депрессивное поведение у животных после воздействия ночного света [110]. Хотя для людей подобных исследований пока не проводилось, но показано, что восстановление циркадных ритмов благоприятно влияет на психическое здоровье. ...
Introduction. Environment and its indicators as health risk factors have been widely studied for a long time. The atmospheric air and factors polluting it are confirmed as the most important environmental factors that influence human’s health. Nevertheless, people spend up to 90% of their time indoors. Indicators of indoor environment have another origins and they can also have another scales. At the same time, these factors can be influenced easily, thus decreasing their negative impact on health. The aim of our review is to study information about impact of physical factors of indoor environment on human organism and methods of maintaining them within safe level. For analysis we chose several factors depending on their prevalence, opportunities to measure their levels and availability of the methods to correct them. Materials and methods. The search was conducted using PubMed, Google Scholar and Elibrary data bases. Fundamental literature, such as legislative act, were used. Results. Nowadays, disease prevention via elimination of risk factors influence on human health is gaining more and more attention. There are various devices that capture air indicators in houses and public buildings. Their use helps to maintain parameters within comfort level. We summarized information about the most important and wide-spread factors, their impact on health, methods for their measurement and solutions for their correction. Nevertheless, there are not enough devices which enable to monitor several important factors simultaneously. That problem leads to using different devices and each of them need calibration and technical service. Conclusion. Nowadays the impact of environmental factors on human health is widely studied and new information about this problem appears constantly. Dynamic monitoring of indicators of environmental factors is necessary for decreasing negative influence on health. An important step towards simultaneous monitoring of the most significant indoor factors is developing of technical solutions which can remove the duty to service many devices separately. These technical solutions can also propose methods for maintaining these factors within safe levels.
... Clinical trials have also shed light on links between chronotype and depressive symptoms. One randomised controlled trial (n = 22 healthy individuals) that aimed to behaviourally advance the sleep-wake timing of evening types demonstrated that a phase advance in the sleep-wake cycle was associated with improvements in selfreported depressive symptoms (Facer-Childs et al. 2019); ...
There is significant interest in the possible influence of chronotype on clinical states in young people with emerging mental disorders. We apply a dynamic approach (bivariate latent change score modelling) to examine the possible prospective influence of chronotype on depressive and hypo/manic symptoms in a youth cohort with predominantly depressive, bipolar, and psychotic disorders (N = 118; 14-30-years), who completed a baseline and follow-up assessment of these constructs (mean interval = 1.8-years). Our primary hypotheses were that greater baseline eveningness would predict increases in depressive but not hypo/manic symptoms. We found moderate to strong autoregressive effects for chronotype (β = -0.447 to -0.448, p < 0.001), depressive (β = -0.650, p < 0.001) and hypo/manic symptoms (β = -0.819, p < 0.001). Against our predictions, baseline chronotypes did not predict change in depressive (β = -0.016, p = 0.810) or hypo/manic symptoms (β = 0.077, p = 0.104). Similarly, the change in chronotype did not correlate with the change in depressive symptoms (β = -0.096, p = 0.295) nor did the change in chronotype and the change in hypo/manic symptoms (β = -0.166, p = 0.070). These data suggest that chronotypes may have low utility for predicting future hypo/manic and depressive symptoms in the short term, or that more frequent assessments over longer periods are needed to observe these associations. Future studies should test whether other circadian phenotypes (e.g. sleep-wake variability) are better indicators of illness course.
... Evening chronotypes and SJL are associated with obesity, lower academic achievement, depression, lower performance, and increased smoking habits [4][5][6]. Interventions for chronotypes and SJL prevent lifestyle-related diseases [7]; however, only a few intervention trials have been reported. The COVID-19 pandemic has delayed workday wake-up times and reduced SJL by prompting quarantining and working from home [8,9]. ...
Chronotype (morningness–eveningness) and social jetlag (SJL; discrepancy in the sleep pattern between the weekday and weekend) are related to eating behavior and health. The association between sleep behavior and the daily macro- and micronutrient eating pattern of each meal (breakfast, lunch, and dinner) have not been discussed well and need more evidence. Here, meal pattern datasets of Japanese participants aged 20–59 years were obtained as averages over 1 month from the data stored in the food-logging app “Asken”. We allocated three groups for each chronotype and SJL. Multiple regression analyses revealed that morning chronotype and small SJL were associated with higher total daily intake of potassium, fiber, magnesium, phosphorus, and vitamin K. Breakfast energy intake and consumption of nutrients, including protein, lipid, carbohydrate, and minerals, were higher in the morning chronotype or small SJL. Lunch intake of potassium, cholesterol, fiber, magnesium, and vitamin K was also higher in the morning chronotype or small SJL. Dinner energy intake and nutrient intake of proteins, lipids, carbohydrates, sodium, and saturated fatty acids were lower in the morning chronotype or small SJL. The current data would help to establish a detailed reference for dietary intake which considers eating patterns over a day.
... Considering the magnitude of effect of the original gender difference (43 min; d = 0.59), this suggests that cognitive fitness levels account for a meaningful amount of variance in sleep timing for women. Later sleep timing has been associated with cardiometabolic, psychological, and performance risks (Partonen, 2015;Facer-Childs et al., 2019). Therefore, cognitive fitness may be a potential intervention target for women athletes under chronic stress to reduce their risk of sleeping later, relative to men athletes. ...
Objectives: Mental fitness is increasingly considered a key component of an athlete’s competitive arsenal. Active domains of mental fitness include cognitive fitness, sleep, and mental health; and these domains can differ between men and women athletes. Our study investigated the associations of cognitive fitness and gender to sleep and mental health, and the interaction between cognitive fitness and gender on sleep and mental health, in competitive athletes during the COVID-19 pandemic.
Methods: 82 athletes competing at levels from regional/state to international (49% women, M-age = 23.3 years) completed measures of self-control, intolerance of uncertainty, and impulsivity (together representing constructs of cognitive fitness), items about sleep (total sleep time, sleep latency, and mid-sleep time on free days) and a measure of mental health (depression, anxiety, and stress).
Results: Women athletes reported lower self-control, higher intolerance of uncertainty, and higher positive urgency impulsivity compared with men athletes. Women reported sleeping later, but this gender difference disappeared after controlling for cognitive fitness. Women athletes—after controlling for cognitive fitness—reported higher depression, anxiety, and stress. Across genders, higher self-control was associated with lower depression, and lower intolerance of uncertainty was associated with lower anxiety. Higher sensation seeking was associated with lower depression and stress, and higher premeditation was associated with greater total sleep time and anxiety. Higher perseverance was associated with higher depression for men—but not women—athletes.
Conclusion: Women athletes in our sample reported poorer cognitive fitness and mental health compared to men athletes. Most cognitive fitness factors protected competitive athletes under chronic stress, but some exposed them to poorer mental health. Future work should examine the sources of gender differences. Our findings suggest a need to develop tailored interventions aimed at improving athlete wellbeing, with a particular focus on women athletes.
... Therefore, there is increasing need to study individuals in their home environment to promote generalizability to real-world contexts. Although field studies do not allow for the control of exogenous influences, an integrated approach may help to shed light on how both biological and environmental factors affect health, physiology and performance 23,26,27 . This protocol was designed specifically to be able to monitor individuals in their home environment whilst following their habitual routines. ...
... In some cases, light exposure can represent the primary or secondary outcome of a specific clinical trial, such as in studies attempting to modify lifestyle to alter light exposure and visual behavior in myopia control (e.g., Ref. 30 ), or studies aimed to optimize light exposure in order to support sleep and/or daytime functioning (e.g., Ref. 59 ). In these studies, personalized light exposure is the study outcome, and therefore measurements need to be sensitive enough to capture change in light patterns in response to the trial intervention. ...
Background
Light exposure is an important driver and modulator of human physiology, behavior and overall health, including the biological clock, sleep-wake cycles, mood and alertness. Light can also be used as a directed intervention, e.g., in the form of light therapy in seasonal affective disorder (SAD), jetlag prevention and treatment, or to treat circadian disorders. Recently, a system of quantities and units related to the physiological effects of light was standardized by the International Commission on Illumination (CIE S 026/E:2018). At the same time, biometric monitoring technologies (BioMeTs) to capture personalized light exposure were developed. However, because there are currently no standard approaches to evaluate the digital dosimeters, the need to provide a firm framework for the characterization, calibration, and reporting for these digital sensors is urgent.
Objective
This article provides such a framework by applying the principles of verification, analytic validation and clinical validation (V3) as a state-of-the-art approach for tools and standards in digital medicine to light dosimetry.
Results
This article describes opportunities for the use of digital dosimeters for basic research, for monitoring light exposure, and for measuring adherence in both clinical and non-clinical populations to light-based interventions in clinical trials.
... Thus, factors including light exposure, work hours, eating habits, physical activity and medication use affect the body according to individual traits/states, such as genome, age, gender, ethnicity and chronotype (Table 1). Circadian hygiene strategies have been shown to be successful in studies that simulate real-life conditions [6]. The temporal flexibility of society would allow such strategies to be adopted more easily. ...
Circadian hygiene, a concept not to be confused with the notion of public or social hygiene, should be discussed among experts and society. Light–dark cycles and other possible synchronizers of the human circadian timing system affect ways of life, including sleeping, eating, working and physical activity. Some of these behaviors have also been investigated individually as synchronizers (e.g., eating times). Therefore, the knowledge held today about circadian rhythms, and their implications for health, allows future perspectives in this field to be mapped. The present article summarizes the latest knowledge on factors influencing circadian rhythms to discuss a perspective for the future of health promotion based on circadian hygiene. However, it is important to highlight that circadian hygiene is the product of an imbrication of individual and societal involvement. First, it is important to adopt practices and devise public health policies in line with circadian hygiene. Second, individual healthy habits require internal rhythms to be examined. Last, the research agenda on circadian hygiene can be developed on a public as well as individual level, raising the question as to how much society is willing to embrace this change.
... From these observations arises the question on whether the evening chronotype can be considered a form of SJL. And the answer is most probably 'no' as although chronotype is a state of phase of entrainment reflecting the continuous adaptations of circadian system to zeitgeber changes [66,67], it also has a genetic basis [68]. SJL is a metric describing the chronic misalignment between the circadian system and social schedules, results from sleep timing variability between weekdays and weekends and includes a component of sleep debt that may influence associated health risks [64]. ...
The objective of this scoping review was to summarize previous studies which examined the effect of day-to-day variability in sleep timing and social jetlag (SJL) on dietary intake. A systematic literature search was conducted in PubMed, Embase, and Clarivate Analytics Web of Science and we identified 22 records. No difference in caloric and macronutrient intake between SJL groups was observed in studies that enrolled healthy young adults. However, studies that enrolled participants with obesity and obesity-related chronic conditions reported a higher caloric intake and a higher intake of carbohydrates, total fat, saturated fats, and cholesterol in participants with SJL than in those without. Most studies reported a lower quality of diet, a delayed mealtime, and eating jetlag in participants with SJL vs. those without SJL. No correlation of day-to-day variability in sleep timing with average caloric intake was observed, but bed-time variability was negatively associated with diet quality. Methodological issues have been identified in sources assessed including study design, power calculation, population enrolled, and tools/metrics used for sleep timing variability assessment. Future well powered longitudinal studies, with clear protocols, standardized metrics, including all age groups from general population are needed to clarify the dietary intake consequences of variability in sleep timing.
... Identifying adolescents who are more evening oriented seems to be a relevant objective to prevent possible future problems in adulthood. Educational interventions aimed at modifying certain aspects of the evening adolescent lifestyle have been shown to be effective (Díaz-Morales et al. 2012;Facer-Childs et al. 2019;Illingworth et al. 2020;Vollmer et al. 2014). Therefore, an adequate evaluation of the M/E trait is vital at this stage of the life cycle. ...
The aim of the present study was to adapt the Morningness-Eveningness-Stability Scale improved (MESSi) to the Spanish adolescent population, testing its factor structure and construct validity. The participants were 725 adolescents (52.9% girls; M = 14.8, SD = 1.99) who completed the MESSi, the Morningness Eveningness Scale of Children (MESC), questions about sleep habits adapted from the School Sleep Habits Survey, and self-reported academic performance. The psychometric results support a three-factor model with the factors of morning affect, eveningness, and distinctness, which show good internal consistency. The pattern of correlations between MESSi and the other measures was in the expected direction. The MESC correlated positively with morning affect and negatively with eveningness, whereas distinctness was uncorrelated. Boys reported higher morningness, whereas girls reported higher distinctness. Eveningness was negatively related to academic performance. Overall, the results support the validity and reliability of the Spanish adolescent version of the MESSi.
... Studies have shown that managing employee health at work can improve employee performance and the company's performance. This issue is becoming more prevalent globally [26][27][28]. ...
Background:
Breakfast is the most important meal of the day and has been associated with longevity. Regular breakfast consumers often have a healthy lifestyle, including a healthy diet and regular physical activity.
Methods:
We examined the association between breakfast type, chronotype (morningness-eveningness), and physical activity in 3395 Japanese workers using a cross-sectional web survey.
Results:
Participants who ate Japanese breakfasts showed an early chronotype, while those who ate breakfast cereal exhibited a later chronotype. Physical activity was positively associated with adopting a Japanese breakfast style. Japanese breakfast eaters performed physical activities from 6:00-9:00 compared with other breakfast eaters.
Conclusion:
Our findings suggest that eating a Japanese breakfast is associated with an earlier chronotype (morningness) and higher physical activity.
... Mendelian randomization results from several studies confirm a causal effect of the 'lifelong intervention' of genetic variation for morning chronotype as protective for psychiatric disorders, especially major depressive disorder [31][32][33]134,135 . A recent randomized control trial that targeted sleep timing, meal timing, light exposure, caffeine intake, napping behaviour and exercise behaviour provided evidence for the feasibility of interventions to produce clinically relevant shifts in circadian rhythms 136 . In recent studies of insomnia and short sleep, a causal link to coronary artery disease and myocardial infarction was demonstrated [114][115][116][117] , further supporting numerous observational studies linking insomnia with cardiac outcomes 137,138 . ...
Circadian rhythms and sleep are fundamental biological processes integral to human health. Their disruption is associated with detrimental physiological consequences, including cognitive, metabolic, cardiovascular and immunological dysfunctions. Yet many of the molecular underpinnings of sleep regulation in health and disease have remained elusive. Given the moderate heritability of circadian and sleep traits, genetics offers an opportunity that complements insights from model organism studies to advance our fundamental molecular understanding of human circadian and sleep physiology and linked chronic disease biology. Here, we review recent discoveries of the genetics of circadian and sleep physiology and disorders with a focus on those that reveal causal contributions to complex diseases. The circadian system and sleep physiology are linked to myriad biological processes, the disruption of which is detrimental to human health. Here, the authors review insights from genetic studies of human circadian and sleep phenotypes and disorders, with a focus on those with causal contributions to other complex diseases.
... Chronotype (i.e., an evening preference) is suggested to be moderately modifiable (Leocadio-Miguel et al. 2021). Nevertheless, some interventions targeting light exposure, fixed meals times, caffeine intake and exercise may induce a phase advance in individuals with late chronotypes, (Facer-Childs et al. 2019;Thomas et al. 2020). Such an effect has not been explored yet in a population with BD. ...
Background
Life expectancy is significantly decreased in bipolar disorder (BD). This is associated with accelerated cellular aging which can be estimated by telomere length (TL). However, specific determinants of shorter TL in BD are under-explored. This study examines whether circadian misalignment (i.e. mismatch between preferred and actual phase of circadian activity rhythms) is associated with shorter TL in BD.
Methods
Euthymic individuals with BD (n = 101) undertook 21 consecutive days of actigraphy recording and completed the Composite Scale of Morningness (CSM) to assess phase preference for activities (chronotype). Polymerase chain reaction was used to measure TL in blood. Cluster analysis identified circadian aligned/misaligned subgroups as defined by preferred (CSM score) and actual phases of activity (actigraphically determined onset of active and inactive periods). We tested for any associations between TL and clusters, with adjustments for between-cluster differences in socio-demographic and illness factors.
Results
We identified three clusters: an "Aligned Morning" cluster (n = 31) with preferred and actual timing of activity in the morning, an "Aligned Evening" cluster (n = 37) with preferred and actual timing of activity in the evening and a "Misaligned" cluster (n = 32) with an evening chronotype, but an earlier objective onset of active periods. After adjustment for confounders, we found that TL was significantly associated with circadian misalignment and older age.
Conclusions
Circadian misalignment may partly explain shorter TL in BD and could contribute to accelerated aging in these individuals.
... Two alternative sets of advice (novel in their formulation but grounded in circadian practice; Abbott et al., 2015) were provided (and remained the same on every subsequent "refresh" monthly reminder) with comparable expected benefits (i.e., balancing out because the first type of advice was slightly less prescriptive but probably easier to follow, and the second slightly more prescriptive but probably more difficult to follow) exerted via two different forms of habits' adjustment (Facer-Childs et al., 2019). Both included elements of the recommendations routinely provided to patients with either a formal diagnosis and/or features of delayed sleep phase type (Abbott et al., 2015), which is common in adolescents and young adults. ...
The aims of the present study were to obtain sleep quality and sleep timing information in a group of university students and to evaluate the effects of a circadian hygiene education initiative. All students of the University of Padova (approximately 64,000) were contacted by e-mail (major campaigns in October 2019 and October 2020) and directed to an ad hoc website for collection of demographics and sleep quality/timing information. Participants (n = 5,740) received one of two sets of circadian hygiene advice (“A regular life” or “Bright days and dark nights”). Every month, they were then asked how easy it had been to comply and provided with the advice again. At any even month from joining, they completed the sleep quality/timing questionnaires again. Information on academic performance was obtained post hoc, together with representative samples of lecture (n = 5,972) and examination (n = 1,800) timings, plus lecture attendances (n = 25,302). Fifty-two percent of students had poor sleep quality, and 82% showed signs of social jetlag. Those who joined in October 2020, after several months of lockdown and distance learning, had better sleep quality, less social jetlag, and later sleep habits. Over approximately a year, the “Bright days and dark nights” advice resulted in significantly earlier get-up times compared with the “A regular life” advice. Similarly, it also resulted in a trend toward earlier midsleep (i.e., the midpoint, expressed as clock time, between sleep onset and sleep offset) and toward a decrease in the latency between wake-up and get-up time, with no impact on sleep duration. Significant changes in most sleep quality and sleep timing variables (i.e., fewer night awakenings, less social jetlag, and delayed sleep timing during lock-down) were observed in both advice groups over approximately a year, mostly in association with pandemic-related events characterizing 2020. Early chronotype students had better academic performances compared with their later chronotype counterparts. In a multivariate model, sleep quality, chronotype and study subject (science and technology, health and medical, or social and humanities) were independent predictors of academic performance. Taken together, these results underlie the importance of designing circadian-friendly university timetables.
Circadian rhythms are important biological processes that are essential to human health and well-being. These rhythms are generated by the internal “body clock” and regulate the sleep-wake cycle and numerous physiological processes. Mutations (i.e., changes in circadian genes) from one generation to the next including underlying genetic issues which may result in one’s inability to receive or process environmental cues can affect the clock’s timing. However, circadian rhythm disruption may also be related to external factors and an individual’s behavior as a result of their sleep timing (chronotype) or due to activities such as trans-meridian travel and shift-work that puts sleep schedules out of sync with daylight exposure. Dysregulation of the body’s internal circadian timekeeping mechanism is an established risk factor for circadian rhythm sleep-wake disorders (CRSWD). This dysregulation is common in modern society and is associated with a number of highly prevalent population diseases including CRSWD. CRSWDs involve a disruption in the timing of physiological processes, including sleep and wake timing. There is evidence of genetic variation playing a role in chronotype, with circadian, behavioral and photo-transduction pathways implicated using large scale GWAS, providing opportunities to better understand the causes and consequences of circadian rhythm disturbances on human physiology. As well, both Advanced and Delayed Sleep Wake Phase Disorders have been linked to rare genetic variation in circadian clock genes in families. In this chapter, we will focus on the genetics of chronotype and CRSWDs in humans, additionally looking at the role of chronomedicine in providing precision medicine for the treatment of CRSWDs. Thus, this chapter seeks to expand our knowledge of the genetic basis of chronotype and CRSWDs.
Objectives
The study aimed to investigate the effect of the circadian timing program (SİZAP) developed for evening-chronotype individuals with obesity on obesity management and sleep quality.
Methods
This single-site, randomized controlled trial with an experimental research design was registered in
ClinicalTrials.gov
. It was reported in accordance with the “Consolidated Standards of Reporting Trials” (CONSORT) randomized controlled trial guidelines. The study sample consisted of 38 evening-chronotype individuals with first-degree obesity, with 19 individuals in each study group. The intervention group's sleep hygiene training was conducted and their lifestyle changes were ensured through SİZAP. The control group followed their normal daily lifestyle. No intervention was made in terms of the dietary practices of both groups. Study data were collected using the personal information form, the anthropometric measurement form, the Horne and Ostberg Morning and Evening Questionnaire (MEQ), the Impact of weight on quality of life–lite (IWQOL-lite), the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS), the sleep diary, and the data tracked via the website and smart bracelets.
Results
It was determined that the participants in the SİZAP group had a statistically significant decrease in the anthropometric measurements and daytime sleepiness (p < 0.05). The sleep quality scores and the scores of the bodily functions sub-dimension of the quality of life scale were significantly better in the intervention group than in the control group (p < 0.05).
Conclusion
It was found that SİZAP is effective in obesity management in evening-chronotype individuals and increases weight loss success and sleep quality.
Keywords
Chronotype, evening chronotype, Obesity, Circadian misalignment, Sleep quality
Dit is het laatste van een drietal artikelen over het verband tussen fysiek prestatievermogen en het 24-uursritme van ons lichaam. In dit artikel gaat het over de vraag op welk moment van de dag je het beste kunt gaan trainen om gezond(er) te worden en te blijven.
We investigated whether chronotype and time-of-day modulate the time course of automatic and controlled semantic processing. Participants performed a category semantic priming task at either the optimal or non-optimal time of day. We varied the prime-target onset asynchrony (100-, 450-, 650-, and 850-ms SOAs) and kept the percentage of unrelated targets constant at 80%. Automatic processing was expected with the short SOA, and controlled processing with longer SOAs. Intermediate-types (Experiment 1) verified that our task was sensitive to capturing both types of processes and served as a reference to assess themin extreme chronotypes. Morning-type and evening-type participants (Experiment 2) differed in the influence of time of testing on priming effects. Morning-types applied control in all conditions, and no performance modulation by time-of-day was observed. In contrast, evening-types were most adversely affected by the time of day to shift from automatic-based to controlled-based responses. Also, they were considerably affected in successfully implementing controlled processing with long intervals, particularly at the non-optimal time of day, with inhibitory priming showing only a marginally significant effect at the longest SOA. These results suggest that extreme chronotypes may be associated with different styles of cognitive control. Morning-types would be driven by a proactive control style, whereas a reactive control style might be applied by evening-types. ARTICLE HISTORY
Deze serie artikelen gaat over het verband tussen fysiek prestatievermogen en het 24-uursritme van ons lichaam. In dit tweede deel gaan we op zoek naar de beste momenten van de dag om topprestaties te leveren en daarvoor te trainen.
The circadian rhythm affects multiple physiological processes, and disruption of the circadian system can be involved in a range of disease-related pathways. The genetic underpinnings of the circadian rhythm have been well-studied in model organisms. Significant progress has been made in understanding how clock genes affect the physiological functions of the nervous system. In addition, circadian timing is becoming a key factor in improving drug efficacy and reducing drug toxicity. The circadian biology of the target cell determines how the organ responds to the drug at a specific time of day, thus regulating pharmacodynamics. The current review brings together recent advances that have begun to unravel the molecular mechanisms of how the circadian clock affects neurophysiological and behavioral processes associated with human brain diseases. We start with a brief description of how the ubiquitous circadian rhythms are regulated at the genetic, cellular, and neural circuit levels, based on knowledge derived from extensive research on model organisms. We then summarize the latest findings from genetic studies of human brain disorders, focusing on the role of human clock gene variants in these diseases. Lastly, we discuss the impact of common dietary factors and medications on human circadian rhythms and advocate for a broader application of the concept of chronomedicine.
That disruptions of the body's internal clockwork can lead to negative health consequences, including cancer, is a plausible hypothesis. Yet, despite strong mechanistic and animal support, the International Agency for Research on Cancer (IARC) experts considered epidemiological evidence as limited regarding the carcinogenicity of "shift-work involving circadian disruption" (2007) and "night shift work" (2019). We use directed acyclic graphs (DAGs) to outline a concept of circadian causes that discloses challenges when choosing appropriate exposure variables. On this basis, we propose to move beyond shift-work alone as a direct cause of disease. Instead, quantifying chronodisruption as individual doses can lead to interpretable circadian epidemiology. The hypothesis is that doses of chronodisruption cause disrupted circadian organisation by leading to desynchronization of circadian rhythms. Chronodisruption can be conceptualized as the split physiological nexus of internal and external times. Biological (or internal) night - an individual's intrinsically favoured sleep time window - could be the backbone of circadian epidemiology. In practice, individual doses that cause disrupted circadian organisation are derived from the intersection of time intervals of being awake and an individual's biological night. After numerous studies counted work shifts, chronobiology may now advance circadian epidemiology with more specific dose estimation - albeit with greater challenges in measurement (time-dependent individual data) and analysis (time-dependent confounding).
Background:
The association between residential greenness and chronotype remains unclear, especially among children. The current study aimed to explore the associations between residential greenness and chronotype parameters in children and examine potential pathways for these associations.
Methods:
In this cross-sectional study, 16,421 children ages 3-12 were included. Two satellite-derived vegetation indices, i.e., the normalized difference vegetation index (NDVI) and the enhanced vegetation index (EVI), were used to estimate residential greenness. The mid-sleep point on a workday (MSW) and the mid-sleep point on free days (MSF) were considered. And mid-sleep time on free days adjusted for sleep debt (MSFsc) was used as an indicator of chronotype. In addition to multivariable linear regression models, subgroup analyses were conducted to explore effect modifiers, and mediation analyses were used to explore possible mediating mechanisms of air pollutants underlying the associations.
Results:
An interquartile range (IQR) increase in both NDVI500-m and EVI500-m was significantly associated with an earlier MSFsc of -0.061 (95 % confidence interval (CI): -0.072, -0.049) and -0.054 (95 % CI: -0.066, -0.042), respectively. Non-linear dose response relationships were discovered between greenness indices and MSFsc and MSF. The results of stratified analyses showed the effect of residential greenness on MSW was stronger among primary school children and individuals with higher household income than among kindergarten children and those with lower household income. The joint mediation effects of PM2.5, PM1, PM10, NO2, and SO2 on the associations of NDVI500-m and EVI500-m with MSFsc were 89.6 % and 76.0 %, respectively.
Conclusions:
Higher levels of residential greenness may have beneficial effects on an earlier chronotype in the child population, by reducing the effects of air pollutants, especially PM2.5. Our research hopes to promote the deployment of green infrastructure and healthy urban design strategies.
The circadian clock regulates multiple aspects of human physiology including immunity. People have a circadian preference termed chronotype. Those with an evening preference may be better suited to shift work, but also carry higher risk of adverse health. Shift work leads to misalignment of circadian rhythms and is associated with increased risk of inflammatory disease such as asthma and cancer. Here, we investigate the association between chronotype, shift work, and rheumatoid arthritis (RA). The associations between exposures of shift work and chronotype on risk of RA were studied in up to 444,210 U.K. Biobank participants. Multivariable logistic regression models were adjusted for covariates: age, sex, ethnicity, alcohol intake, smoking history, Townsend Deprivation Index (TDI), sleep duration, length of working week, and body mass index (BMI). After adjusting for covariates, individuals with a morning chronotype had lower odds of having rheumatoid arthritis (RA; odds ratio [OR]: 0.93, 95% confidence interval [CI]: 0.88-0.99) when compared to intermediate chronotypes. The association between morning chronotype and RA persisted with a more stringent RA case definition (covariate-adjusted OR: 0.89, 95% CI: 0.81-0.97). When adjusted for age, sex, ethnicity, and TDI, shift workers had higher odds of RA (OR: 1.22, 95% CI: 1.1-1.36) compared to day workers that attenuated to the null after further covariate adjustment (OR: 1.1, 95% CI: 0.98-1.22). Morning chronotypes working permanent night shifts had significantly higher odds of RA compared to day workers (OR: 1.89, 95% CI: 1.19-2.99). These data point to a role for circadian rhythms in RA pathogenesis. Further studies are required to determine the mechanisms underlying this association and understand the potential impact of shift work on chronic inflammatory disease and its mediating factors.
We examined the associations of chronotype with behavior problems in a cross-sectional study of 957 Colombian adolescents (mean age, 14.6 years; 56% female), in addition to the mediating role of social jetlag. The midpoint of bedtime and waketime on free days, corrected for sleep debt accumulated during school week (MSFsc), was estimated from parent reports and used to assess chronotype. Behavior problems were evaluated through the Youth Self-Report (YSR) and the parent-completed Child Behavior Checklist (CBCL) questionnaires. We estimated adjusted mean differences with 95% CI in externalizing, internalizing, attention, social, and thought problem scores per one hour difference in chronotype using linear regression. Later chronotype was related to internalizing and externalizing behavior problems. Eveningness was associated with higher adjusted mean YSR scores (unit difference per hour) in externalizing behavior (1.0; 95% CI: 0.6, 1.5), internalizing behavior (0.6; 95% CI: 0.2, 1.1), attention problems (0.2; 95% CI: 0.0, 0.3), social problems (0.4; 95% CI: 0.1, 0.8), and thought problems (0.3; 95% CI: 0.1, 0.6). Similar patterns were observed with the CBCL. The associations of chronotype with somatic complaints and social problems were stronger in boys than they were in girls. Later chronotype was related to social jetlag but social jetlag was only associated with somatic complaints and attention problems, and mediated 16% and 26% of their corresponding associations with chronotype. In conclusion, later chronotype is associated with behavior problems in adolescence. Social jetlag does not substantially mediate these associations.
Circadian medicine, the study of the effects of time on health and disease has seen an uprising in recent years as a means to enhance health and performance, and optimize treatment timing. Our endogenous time generating system -the circadian clock- regulates behavioural, physiological and cellular processes. Disruptions of the clock, via external factors like shift work or jet lag, or internal perturbations such as genetic alterations, are linked to an increased risk of various diseases like obesity, diabetes, cardiovascular diseases and cancer. By aligning an individual's circadian clock with optimal times for performing daily routines, physical and mental performance, and also the effectiveness of certain therapies can be improved. Despite the benefits of circadian medicine, the lack of non-invasive tools for characterizing the clock limits the potential of the field. TimeTeller is a non-invasive molecular/digital tool for the characterization of circadian rhythms and prediction of daily routines, including treatment timing, to unlock the potential of circadian medicine and implementing it in various settings. Given the multiple known and potentially yet unknown dependent health factors of individual circadian rhythms, the utility of this emerging biomarker is best exploited in data driven, personalized medicine use cases, using health information across lifestyle, care, and research settings.
Background:
Poor sleepers have a higher prevalence of mental health problems, and vice versa. However, the mechanisms underlying this association remain unknown. We aimed to examine the bidirectional association between sleep quality and mental health, and further explore the moderating effects of PER3 gene DNA methylation on the association.
Methods:
This prospective longitudinal study was conducted from April 2019 to May 2021, integrated questionnaire and blood sample data from 2 universities in Anhui and Jiangxi Provinces. The current study recruited 1179 young adults at baseline and conducted the follow-up survey among 1135 half a year later. The sleep quality and depressive symptoms, anxiety symptoms, and stress symptoms were assessed using a questionnaire at baseline and follow-up. Blood samples were collected at baseline, and MethyTarget™ was used to detect the PER3 gene DNA methylation level. A cross-lag model was used to examine the bidirectional association between sleep quality and mental health. The PROCESS plug-in of SPSS software was used to analyse the moderating effects of PER3 gene DNA methylation.
Results:
Cross-lagged analyses suggested a significant bidirectional relationship between poor sleep quality and depressive symptoms, anxiety symptoms, and stress symptoms. Sleep quality at baseline was a significant predictor of depressive symptoms (β = 0.344, P < 0.001), anxiety symptoms (β = 0.348, P < 0.001), and stress symptoms (β = 0.324, P < 0.001) half a year later. Depressive symptoms (β = 0.049, P < 0.001), anxiety symptoms (β = 0.055, P < 0.001), and stress symptoms (β = 0.063, P < 0.001) at baseline were also significant predictors of poor sleep quality half a year later. Furthermore, PER3 gene DNA methylation has negative moderating effects between sleep quality at baseline and depressive symptoms (β = -11.706, P = 0.012), anxiety symptoms (β = -10.289, P = 0.019), and stress symptoms (β = -10.799, P = 0.024) half a year later and a sex difference. Among boys, PER3 gene DNA methylation has positive moderating effects between anxiety symptoms at baseline and sleep quality (β = 3.337, P = 0.018) half a year later. However, there was no association between mental health at baseline and sleep quality half a year later among girls.
Conclusion:
Bidirectional relationships were identified between sleep quality and mental health among Chinese young adults during the study period. DNA methylation evidence supports a negative moderating effect of PER3 gene DNA methylation on the relationship between sleep quality at baseline and mental health half a year later and had sex differences. Among boys, PER3 gene DNA methylation had positive moderating effects between anxiety symptoms at baseline and sleep quality half a year later. These findings point to the importance of circadian clock gene DNA methylation in the relationship between sleep quality and mental health.
Individual preferred timing of sleep and activity patterns, known as circadian preference, ranges from definitely morning types to definitely evening types. Being an evening type has been linked to adverse sleep and mental health outcomes. This study aimed to explore the associations between circadian preference and self-reported sleep, depression, anxiety, quality of life, loneliness, and self-harm/suicidal thoughts. Data stem from a national survey of students in higher education in Norway (the SHoT-study). All 169,572 students in Norway were invited to participate, and 59,554 students (66.5% women) accepted (response rate = 35.1%). Circadian preference was associated with sleep and mental health outcomes in a dose-response manner. For both genders, being an evening type (either definitely evening or more evening than morning) was associated with an increase in age-adjusted relative risk (RR-adjusted; range = 1.44 to 2.52 vs. 1.15 to 1.90, respectively) across all outcomes compared with definitely morning types. Overall, the present study provides further evidence that evening circadian preference is associated with adverse sleep and mental health outcomes in young adults. As such, future efforts to improve sleep and mental health in young adults should consider their circadian preferences.
The daily alternation between sleep and wakefulness is one of the most dominant features of our lives and is a manifestation of the intrinsic 24 h rhythmicity underlying almost every aspect of our physiology. Circadian rhythms are generated by networks of molecular oscillators in the brain and peripheral tissues that interact with environmental and behavioural cycles to promote the occurrence of sleep during the environmental night. This alignment is often disturbed, however, by contemporary changes to our living environments, work or social schedules, patterns of light exposure, and biological factors, with consequences not only for sleep timing but also for our physical and mental health. Characterised by undesirable or irregular timing of sleep and wakefulness, in this Series paper we critically examine the existing categories of circadian rhythm sleep–wake disorders and the role of the circadian system in their development. We emphasise how not all disruption to daily rhythms is driven solely by an underlying circadian disturbance, and take a broader, dimensional approach to explore how circadian rhythms and sleep homoeostasis interact with behavioural and environmental factors. Very few high-quality epidemiological and intervention studies exist, and wider recognition and treatment of sleep timing disorders are currently hindered by a scarcity of accessible and objective tools for quantifying sleep and circadian physiology and environmental variables. We therefore assess emerging wearable technology, transcriptomics, and mathematical modelling approaches that promise to accelerate the integration of our knowledge in sleep and circadian science into improved human health.
Background
Emerging research suggests that food intake timing, eating behavior and food preference are associated with aspects of the circadian system function but the role that the circadian system may play in binge eating (BE) behavior in humans remains unclear.
Objective
To systematically evaluate the evidence for circadian system involvement in BE behavior.
Methods
Systematic searches of PubMed, EMBASE, and Scopus were performed for reports published from inception until May 2020 (PROSPERO Registration CRD42020186325). Searches were conducted by combining Medical Subject Headings related to the circadian system, BE behavior, and/or interventions. Observational and interventional studies in humans with BE behavior published in peer-review journals in the English language were included. Studies were assessed using quality and risk of bias tools (AXIS, ROB 2.0, or ROBINS).
Results
The search produced 660 articles, 51 of which were included in this review. Of these articles, 46 were observational studies and 5 were interventional trials. Evidence from these studies suggests that individuals with BE behavior tend to have more food intake, more binge cravings, and more BE episodes later in the day. Hormonal and day/night locomotor activity rhythm disturbances may be associated with BE behavior. Furthermore, late diurnal preference (“eveningness”) was associated with BE behavior and chronobiological interventions that shift the circadian clock earlier (e.g., morning bright light therapy) were found to possibly decrease BE behavior. Substantive clinical overlap exists between BE and night eating behavior. However, there is a significant knowledge gap regarding their potential relationship with the circadian system. Limitations include the lack of studies that use best-established techniques to assess the chronobiology of BE behavior, heterogeneity of participants, diagnostic criteria, and study design, which preclude a meta-analytic approach.
Conclusion
Current evidence, although limited, suggests that the circadian system may play a role in the etiology of BE behavior. Further mechanistic studies are needed to fully characterize a potential role of the circadian system in BE behavior. A chronobiological approach to studying BE behavior may lead to identification of its neurobiological components and development of novel therapeutic interventions.
Systematic review registration
[ https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020186325 ], identifier [CRD42020186325].
Background
Accumulating evidence implicates sleep and circadian rhythm disturbance in obsessive-compulsive disorder (OCD). However, a multimethod characterization of sleep and circadian rhythms in OCD, their association with symptom severity, and the functional relationship between these variables is lacking.
Methods
The present study measured multiple indicators of sleep and circadian rhythms in a sample of adults with OCD, adults without OCD, and healthy controls (n = 74). Participants completed measures of morningness-eveningness, delayed sleep-wake phase disorder (DSWPD), insomnia symptoms, and OCD symptoms, as well as one week of sleep monitoring via a sleep diary and actigraphy.
Results
Delayed circadian rhythms (higher eveningness, later mid-sleep timing, and higher rates of DSWPD) and higher insomnia symptoms were observed in those with OCD compared to healthy controls, as well as associations between delayed circadian rhythms and insomnia symptoms and OCD symptom severity across the full sample. Further, insomnia symptoms mediated the relationship between delayed circadian rhythms and OCD symptoms. In contrast, there were no links between total sleep time or sleep quality and OCD.
Limitations
Data collection during COVID-19 pandemic, correlational data, no physiological measure of circadian rhythms.
Conclusions
These findings highlight a robust association between delayed circadian rhythms and OCD and suggest insomnia symptoms may be one mechanism in this relationship. Sleep and circadian rhythm disturbance may be novel targets for OCD treatment.
The circadian rhythm is crucial for physiological and behavioral functions. Chronotype, which represents individual preferences for activity and performance, is associated with human health issues, particularly psychiatric disorders. This narrative review, which focuses on the relationship between chronotype and mental disorders, provides an insight into the potential mechanism. Recent evidence indicates that (1) the evening chronotype is a risk factor for depressive disorders and substance use disorders, whereas the morning chronotype is a protective factor. (2) Evening chronotype individuals with bipolar disorder tend to have more severe symptoms and comorbidities. (3) The evening chronotype is only related to anxiety symptoms. (4) The relationship between chronotype and schizophrenia remains unclear, despite increasing evidence on their link. (5) The evening chronotype is significantly associated with eating disorders, with the majority of studies have focused on binge eating disorders. Furthermore, the underlying mechanisms or influence factors are described in detail, including clock genes, brain characteristics, neuroendocrinology, the light/dark cycle, social factors, psychological factors, and sleep disorders. These findings provide the latest evidence on chronotypes and psychiatric disorders and serve as a valuable reference for researchers.
Background
The clinical importance of morningness-eveningness, especially in mood disorders, is prevailing. The differential relation of chronotype with diagnoses of early-onset mood disorders, mood symptoms, anxiety, and quality of life was evaluated.
Methods
Early-onset mood disorder patients [n = 419; 146 major depressive disorder (MDD); 123 bipolar I disorder (BDI); 150 bipolar II disorder (BDII)] from the Mood Disorder Cohort Research Consortium were assessed for chronotype using the composite scale for morningness (CSM) and its association with clinical variables obtained during the clinician-verified euthymic state.
Results
The mean total CSM of BDI was significantly higher than MDD and BDII (p < 0.001). In all types of mood disorders, higher total CSM was associated with lower Quick inventory of depressive symptomatology (p < 0.005) and higher WHO quality of life (p < 0.005). Such negative correlations between the total CSM and Montgomery-Asberg depression rating were significant in MDD and BDI (p < 0.05) and marginally significant in BDII (p = 0.077). CSM was a significant contributor to quality of life in BDI (p < 0.001) and BDII (p = 0.011), but it was not for MDD.
Limitations
The defined ‘euthymic state’ that may not fully reflect the remission of episode; limited generalizability due to clinical characteristic of early-onset mood disorder; the disparity between diurnal preference measured by the CSM and chronotype; possible effects of the last mood episode polarity and medication; and, lack of control group.
Conclusion
Less eveningness was associated with less severe depressive symptoms and better quality of life. This suggests that morningness may reduce residual depressive symptoms and recover function of patients.
Рreference for later bedtimes and rise times characterize evening chronotypes. Evening chronotypes suffer from early work start times thereby contradicting their circadian rhythms, as a result, a late wake-up time on free days reflect an attempt to compensate for a sleep debt accumulated on work days. This leads to a misalignment in sleep timing between weekdays and weekends, known as social jetlag (SJL), which is associated with increased health risk. Here we analyze the risks that evening preferences related with SJL bear and their potential impact on health, and also talk about possible correction measures, primarily of a behavioral nature, using literature data from PubMed and Embase database. Evening chronotype can compromise the maintenance of a healthy lifestyle. Evening chronotypes are more prone to bedtime screen use, which can suppress melatonin rise and extend wakefulness activities far into the night, thus dragging sleep and meal timing to later periods. Preference towards later time-of-day is linked with higher intake of total calories and fats, as well as unhealthy dietary habits (breakfast skipping, snacking, longer eating duration). Evening chronotype also has been associated with high caffeinated drinks intake, alcohol consumption and smoking, low physical activities. It has been found that unhealthy behavior might function as the promoting factors to circadian misalignment and greater SJL. Interventions to prevent and control unhealthy behaviors among evening types should be included in preventive measures of SJL.
Individual preference for morning or evening activities (chronotype), affect, hardiness, and talent are associated with a variety of performance outcomes. This longitudinal study was designed to investigate the degree to which these variables are associated with academic, physical, and military performance. Self-reported measures of chronotype, affect, and hardiness were collected from 1149 cadets from the Class of 2016 upon entry to the United States Military Academy. Talent, a composite of academic, leadership, and physical fitness scores were drawn from cadet records. Academic, military, and physical performance measures were collected at graduation 4 years later. The results indicated that a morning orientation was associated with better physical and military performance. Higher talent scores, as well as lower levels of negative affect, were associated with better performance across all three performance measures. Hardiness was only associated with military performance. The findings suggest that a morning orientation and less negative affect may result in better performance overall within a challenging and structured military environment. Future studies of chronotype shifts may provide further insight into associated performance benefits.
Key points
Exercise elicits circadian phase‐shifting effects, but additional information is needed.
The phase–response curve describing the magnitude and direction of circadian rhythm phase shifts, depending on the time of the zeigeber (time cue) stimulus, is the most fundamental chronobiological tool for alleviating circadian misalignment and related morbidity.
Fifty‐one older and 48 young adults followed a circadian rhythms measurement protocol for up to 5.5 days, and performed 1 h of moderate treadmill exercise for 3 consecutive days at one of eight times of the day/night.
Temporal changes in the phase of 6‐sulphatoxymelatonin (aMT6s) were measured from evening onset, cosine acrophase, morning offset and duration of excretion. Significant phase–response curves were established for aMT6 onset and acrophase with large phase delays from 7:00 pm to 10:00 pm and large phase advances at both 7:00 am and from 1:00 pm to 4:00 pm. Delays or advances would be desired, for example, for adjustment to westward or eastward air travel, respectively.
Along with known synergism with bright light, the above PRCs with a second phase advance region (afternoon) could support both practical and clinical applications.
Abstract
Although bright light is regarded as the primary circadian zeitgeber, its limitations support exploring alternative zeitgebers. Exercise elicits significant circadian phase‐shifting effects, but fundamental information regarding these effects is needed. The primary aim of the present study was to establish phase–response curves (PRCs) documenting the size and direction of phase shifts in relation to the circadian time of exercise. Aerobically fit older (n = 51; 59–75 years) and young adults (n = 48; 18–30 years) followed a 90 min laboratory ultrashort sleep–wake cycle (60 min wake/30 min sleep) for up to 5½ days. At the same clock time on three consecutive days, each participant performed 60 min of moderate treadmill exercise (65–75% of heart rate reserve) at one of eight times of day/night. To describe PRCs, phase shifts were measured for the cosine‐fitted acrophase of urinary 6‐sulphatoxymelatonin (aMT6s), as well as for the evening rise, morning decline and change in duration of aMT6s excretion. Significant PRCs were found for aMT6s acrophase, onset and duration, with peak phase advances corresponding to clock times of 7:00 am and from 1:00 pm to 4:00 pm, delays from 7:00 pm to 10:00 pm, and minimal shifts around 4:00 pm and 2:00 am. There were no significant age or sex differences. The amplitudes of the aMT6s onset and acrophase PRCs are comparable to expectations for bright light of equal duration. The phase advance to afternoon exercise and the exercise‐induced PRC for change in aMT6s duration are novel findings. The results support further research exploring additive phase‐shifting effects of bright light and exercise and health benefits.
Background
Whether you are a morning lark or a night owl has proven to be a key contributor in the timing of peak athletic performance. Recent evidence suggests that accounting for these differences, known as one’s chronotype, results in significantly different diurnal performance profiles. However, there is limited research investigating multiple measures of performance simultaneously over the course of a socially constrained day.
Objectives
This study aimed to investigate the impact of chronotype on indices of cognitive and physical performance at different times of day in healthy volunteers.
Methods
We recruited 56 healthy individuals categorised as early (ECT, n = 25) or late (LCT, n = 31) chronotypes using the Munich ChronoType Questionnaire, circadian phase markers and objective actigraphy. Measures of cognitive and physical performance, along with self-reported daytime sleepiness, were taken at multiple times of day (14:00 h, 20:00 h and 08:00 h the following morning).
Results
Here, we find significantly different diurnal variation profiles between ECTs and LCTs, for daytime sleepiness, psychomotor vigilance, executive function and isometric grip strength. LCTs were significantly impaired in all measures in the morning compared to ECTs.
Conclusion
Our results provide evidence to support the notion that ‘night owls’ are compromised earlier in the day. We offer new insight into how differences in habitual sleep patterns and circadian rhythms impact cognitive and physical measures of performance. These findings may have implications for the sports world, e.g. athletes, coaches and teams, who are constantly looking for ways to minimise performance deficits and maximise performance gains.
Later chronotype (i.e. evening preference) and later timing of sleep have been associated with greater morbidity, including higher rates of metabolic dysfunction and cardiovascular disease (CVD). However, no one has examined whether chronotype is associated with mortality risk to date. Our objective was to test the hypothesis that being an evening type is associated with increased mortality in a large cohort study, the UK Biobank. Our analysis included 433 268 adults aged 38–73 at the time of enrolment and an average 6.5-year follow-up. The primary exposure was chronotype, as assessed through a single self-reported question-defining participants as definite morning types, moderate morning types, moderate evening types or definite evening types. The primary outcomes were all-cause mortality and mortality due to CVD. Prevalent disease was also compared among the chronotype groups. Analyses were adjusted for age, sex, ethnicity, smoking, body mass index, sleep duration, socioeconomic status and comorbidities. Greater eveningness, particularly being a definite evening type, was significantly associated with a higher prevalence of all comorbidities. Comparing definite evening type to definite morning type, the associations were strongest for psychological disorders (OR 1.94, 95% CI 1.86–2.02, p = < 0.001), followed by diabetes (OR 1.30, 95% CI 1.24–1.36, p = < 0.001), neurological disorders (OR 1.25, 95% CI 1.20–1.30, p = < 0.001), gastrointestinal/abdominal disorders (OR 1.23, 95% CI 1.19–1.27, p = < 0.001) and respiratory disorders (OR 1.22, 95% CI 1.18–1.26, p = < 0.001). The total number of deaths was 10 534, out of which 2127 were due to CVD. Greater eveningness, based on chronotype as an ordinal variable, was associated with a small increased risk of all-cause mortality (HR 1.02, 95% CI 1.004–1.05, p = 0.017) and CVD mortality (HR 1.04, 95% CI 1.00–1.09, p = 0.06). Compared to definite morning types, definite evening types had significantly increased risk of all-cause mortality (HR 1.10, 95% CI 1.02–1.18, p = 0.012). This first report of increased mortality in evening types is consistent with previous reports of increased levels of cardiometabolic risk factors in this group. Mortality risk in evening types may be due to behavioural, psychological and physiological risk factors, many of which may be attributable to chronic misalignment between internal physiological timing and externally imposed timing of work and social activities. These findings suggest the need for researching possible interventions aimed at either modifying circadian rhythms in individuals or at allowing evening types greater working hour flexibility.
Study Objectives
To investigate the short- and longer-term impact of a 45-min delay in school start time on sleep and well-being of adolescents.
Methods
The sample consisted of 375 students in grades 7–10 (mean age ± SD: 14.6 ± 1.15 years) from an all-girls’ secondary school in Singapore that delayed its start time from 07:30 to 08:15. Self-reports of sleep timing, sleepiness, and well-being (depressive symptoms and mood) were obtained at baseline prior to the delay, and at approximately 1 and 9 months after the delay. Total sleep time (TST) was evaluated via actigraphy.
Results
After 1 month, bedtimes on school nights were delayed by 9.0 min, while rise times were delayed by 31.6 min, resulting in an increase in time in bed (TIB) of 23.2 min. After 9 months, the increase in TIB was sustained, and TST increased by 10.0 min relative to baseline. Participants also reported lower levels of subjective sleepiness and improvement in well-being at both follow-ups. Notably, greater increase in sleep duration on school nights was associated with greater improvement in alertness and well-being.
Conclusions
Delaying school start time can result in sustained benefits on sleep duration, daytime alertness, and mental well-being even within a culture where trading sleep for academic success is widespread.
Circadian rhythms, metabolism, and nutrition are intimately linked [1, 2], although effects of meal timing on the human circadian system are poorly understood. We investigated the effect of a 5-hr delay in meals on markers of the human master clock and multiple peripheral circadian rhythms. Ten healthy young men undertook a 13-day laboratory protocol. Three meals (breakfast, lunch, dinner) were given at 5-hr intervals, beginning either 0.5 (early) or 5.5 (late) hr after wake. Participants were acclimated to early meals and then switched to late meals for 6 days. After each meal schedule, participants’ circadian rhythms were measured in a 37-hr constant routine that removes sleep and environmental rhythms while replacing meals with hourly isocaloric snacks. Meal timing did not alter actigraphic sleep parameters before circadian rhythm measurement. In constant routines, meal timing did not affect rhythms of subjective hunger and sleepiness, master clock markers (plasma melatonin and cortisol), plasma triglycerides, or clock gene expression in whole blood. Following late meals, however, plasma glucose rhythms were delayed by 5.69 ± 1.29 hr (p < 0.001), and average glucose concentration decreased by 0.27 ± 0.05 mM (p < 0.001). In adipose tissue, PER2 mRNA rhythms were delayed by 0.97 ± 0.29 hr (p < 0.01), indicating that human molecular clocks may be regulated by feeding time and could underpin plasma glucose changes. Timed meals therefore play a role in synchronizing peripheral circadian rhythms in humans and may have particular relevance for patients with circadian rhythm disorders, shift workers, and transmeridian travelers.
The 10-min psychomotor vigilance task (PVT) has often been used to assess the impact of sleep loss
on performance. Due to time constraints, however, regular testing may not be practical in field studies.
The aim of the present study was to examine the suitability of tests shorter than 10 min. in duration.
Changes in performance across a night of sustained wakefulness were compared during a standard
10-min PVT, the first 5 min of the PVT, and the first 2 min of the PVT. Four performance metrics
were assessed: (1) mean reaction time (RT), (2) fastest 10% of RT, (3) lapse percentage, and (4) slowest
10% of RT. Performance during the 10-min PVT significantly deteriorated with increasing wakefulness
for all metrics. Performance during the first 5 min and the first 2 min of the PVT deteriorated in a
manner similar to that observed for the whole 10-min task, with all metrics except lapse percentage displaying
significant impairment across the night. However, the shorter the task sampling time, the less
sensitive the test is to sleepiness. Nevertheless, the 5-min PVT may provide a viable alternative to the
10-min PVT for some performance metrics.
Team performance is a complex phenomenon involving numerous influencing factors including physiology, psychology, and management. Biological rhythms and the impact of circadian phenotype have not been studied for their contribution to this array of factors so far despite our knowledge of the circadian regulation of key physiological processes involved in physical and mental performance. This study involved 216 individuals from 12 different teams who were categorized into circadian phenotypes using the novel RBUB chronometric test. The composition of circadian phenotypes within each team was used to model predicted daily team performance profiles based on physical performance tests. Our results show that the composition of circadian phenotypes within teams is variable and unpredictable. Predicted physical peak performance ranged from 1:52 to 8:59 p.m. with performance levels fluctuating by up to 14.88% over the course of the day. The major predictor for peak performance time in the course of a day in a team is the occurrence of late circadian phenotypes. We conclude that circadian phenotype is a performance indicator in teams that allows new insight and a better understanding of team performance variation in the course of a day as often observed in different groupings of individuals.
Today's modern society is exposed to artificial electric lighting in addition to the natural light-dark cycle. Studies assessing the impact of electric light exposure on sleep and its relation to work hours are rare due to the ubiquitous presence of electricity. Here we report a unique study conducted in two phases in a homogenous group of rubber tappers living and working in a remote area of the Amazon forest, comparing those living without electric light (n = 243 in first phase; n = 25 in second phase) to those with electric light at home (n = 97 in first phase; n = 17 in second phase). Questionnaire data (Phase 1) revealed that rubber tappers with availability of electric light had significantly shorter sleep on work days (30 min/day less) than those without electric light. Analysis of the data from the Phase 2 sample showed a significant delay in the timing of melatonin onset in workers with electric light compared to those without electric light (p < 0.01). Electric lighting delayed sleep onset and reduced sleep duration during the work week and appears to interfere with alignment of the circadian timing system to the natural light/dark cycle.
The aim of this study was to compare morning and evening time-trial performance, RPE and mood state of trained swimmers, taking into account chronotype, habitual training time-of-day and PERIOD3 (PER3) variable number tandem repeat genotype.
Twenty-six swimmers (18 males, age: 32.6 ± 5.7 years) swam 200 m time trials (TT) at 06h30 and 18h30 in a randomised order.
There was no difference between morning and evening performance when the swimmers were considered as a single group (06h30: 158.8 ± 22.7 s, 18h30: 158.5 ± 22.0 s, p = 0.611). However, grouping swimmers by chronotype and habitual training time-of-day allowed us to detect significant diurnal variation in performance, such that morning-type swimmers and those who habitually train in the morning were faster in the 06h30 TT (p = 0.036 and p = 0.011, respectively). This was accompanied by lower ratings of perceived exertion (RPE) scores post-warm-up, higher vigour and lower fatigues scores prior to the 06h30 TT in morning-type swimmers or those who trained in the morning. Similarly, neither types and those who trained in the evenings had lower fatigue and higher vigour prior to the 18h30 TT.
It appears that both chronotype and habitual training time-of-day need to be considered when assessing diurnal variation in performance. From a practical point of view, athletes and coaches should be aware of the potentially powerful effect of training time on shifting time-of-day variation in performance.
The human circadian timing system is most sensitive to the phase-shifting effects of light during the biological nighttime, a time at which humans are most typically asleep. The overlap of sleep with peak sensitivity to the phase-shifting effects of light minimizes the effectiveness of using light as a countermeasure to circadian misalignment in humans. Most current light exposure treatments for such misalignment are mostly ineffective due to poor compliance and secondary changes that cause sleep deprivation. Using a 16-day, parallel group design, we examined whether a novel sequence of light flashes delivered during sleep could evoke phase changes in the circadian system without disrupting sleep. Healthy volunteers participated in a 2-week circadian stabilization protocol followed by a 2-night laboratory stay. During the laboratory session, they were exposed during sleep to either darkness (n = 7) or a sequence of 2-msec light flashes given every 30 sec (n = 6) from hours 2 to 3 after habitual bedtime. Changes in circadian timing (phase) and micro- and macroarchitecture of sleep were assessed. Subjects exposed to the flash sequence during sleep exhibited a delay in the timing of their circadian salivary melatonin rhythm compared with the control dark condition (p < 0.05). Confirmation that the flashes penetrated the eyelids is presented by the occurrence of an evoked response in the EEG. Despite the robust effect on circadian timing, there were no large changes in either the amount or spectral content of sleep (p values > 0.30) during the flash stimulus. Exposing sleeping individuals to 0.24 sec of light spread over an hour shifted the timing of the circadian clock and did so without major alterations to sleep itself. While a greater number of matched subjects and more research will be necessary to ascertain whether these light flashes affect sleep, our data suggest that this type of passive phototherapy might be developed as a useful treatment for circadian misalignment in humans.
Travel across time zones causes jet lag and is accompanied by deleterious effects on sleep and performance in athletes. These poor performances have been evaluated in field studies but not in laboratory conditions. The purpose of this study was to evaluate, in athletes, the impact of 5-h phase advance on the architecture of sleep and physical performances (Wingate test). In a sleep laboratory, 16 male athletes (age: 22.2 ± 1.7 years, height: 178.3 ± 5.6 cm, body mass: 73.6 ± 7.9 kg) spent 1 night in baseline condition and 2 nights, 1 week apart, in phase shift condition recorded by electroencephalography to calculate sleep architecture variables. For these last 2 nights, the clock was advanced by 5 h. Core body temperature rhythm was assessed continuously. The first night with phase advance decreased total sleep time, sleep efficiency, sleep onset latency, stage 2 of nonrapid eye movement (N2), and rapid eye movement (REM) sleep compared with baseline condition, whereas the second night decreased N2 and increased slow-wave sleep and REM, thus improving the quality of sleep. After phase advance, mean power improved, which resulted in higher lactatemia. Acrophase and bathyphase of temperature occurred earlier and amplitude decreased in phase advance but the period was not modified. These results suggest that a simulated phase shift contributed to the changes in sleep architecture, but did not significantly impair physical performances in relation with early phase adjustment of temperature to the new local time.
We hypothesized that professional football teams would perform better than anticipated during games occurring close to their circadian peak in performance.
We reviewed the past 40 years of evening and daytime professional football games between west coast and east coast United States teams. In order to account for known factors influencing football game outcomes we compared the results to the point spread which addresses all significant differences between opposing teams for sports betting purposes. One sample t-tests, Wilcoxon signed ranked tests, and linear regression were performed. Comparison to day game data was included as a control.
Academic medical center.
N/A.
N/A.
The results were strongly in favor of the west coast teams during evening games against east coast teams, with the west coast teams beating the point spread about twice as often (t = 3.95, P < 0.0001) as east coast teams. For similar daytime game match-ups, we observed no such advantage.
Sleep and circadian physiology have profound effects on human function including the performance of elite athletes. Professional football players playing close to the circadian peak in performance demonstrate a significant athletic advantage over those who are playing at other times. Application of this knowledge is likely to enhance human performance.
Smith RS; Efron B; Mah CD; Malhotra A. The impact of circadian misalignment on athletic performance in professional football players. SLEEP 2013;36(12):1999-2001.
Certain preferences for the timing of daily activities (chronotype) may predispose an individual to sleep problems and mood disorders. In this study, we have examined the link between chronotypes and depression. Participants (N = 6071) were recruited from a random sample of the general population aged 25 to 74 yrs living in defined geographical areas, as part of the National FINRISK Study in 2007 in Finland. Chronotype assessment was based on six items from the original Horne-Östberg Morningness-Eveningness Questionnaire. Depression was assessed with four self-reported items, including two probes for a diagnosis of a major depressive episode, diagnosed or treated depression, and use of antidepressants. We also analyzed correlations between chronotype and several health indicators, such as systolic and diastolic blood pressures, resting heart rate, weight, and waist circumference. The odds ratios for a range of indicators of depression were higher for evening types (2.7- to 4.1-fold) and intermediate types (1.5- to 1.9-fold) than for morning types. Our results suggest that individuals having a preference for evening hours to carry out their daily activities are prone to depression. (Author correspondence: ilona.merikanto@helsinki.fi).
In randomised trials, rather than comparing randomised groups directly some researchers carry out a significance test comparing a baseline with a final measurement separately in each group.
We give several examples where this has been done. We use simulation to demonstrate that the procedure is invalid and also show this algebraically.
This approach is biased and invalid, producing conclusions which are, potentially, highly misleading. The actual alpha level of this procedure can be as high as 0.50 for two groups and 0.75 for three.
Randomised groups should be compared directly by two-sample methods and separate tests against baseline are highly misleading.
In public health, mood disorders are among the most important mental impairments. Patients with depressive episodes exhibit daily mood variations, abnormal patterns in sleep-wake behavior, and in the daily rhythms of several endocrine-metabolic parameters. Although the relationship between the sleep/circadian processes and mood disorders is poorly understood, clock-related therapies, such as light therapy, sleep deprivation, and rigid sleep schedules, have been shown to be effective treatments. Several studies investigated the relationship between circadian phenotype (chronotype) and depression. These focused mainly on urban populations and assessed diurnal preferences (Morningness-Eveningness score) rather than the actual timing of sleep and activity. Here, we used the Beck Depression Inventory (BDI) in an essentially rural population (N?=?4051), and investigated its relation to circadian phenotype (chronotype and social jetlag), assessed with the Munich Chronotype Questionnaire (MCTQ). In our study design, we (i) normalized both chronotype and BDI scores for age and sex (MSF(sas) and BDI(as), respectively); (ii) calculated individual social jetlag (misalignment of the biological and social time); and (iii) investigated the relationship between circadian phenotypes and BDI scores in a population homogeneous in respect to culture, socioeconomic factors, and daily light exposure. A 15.65% (N?=?634) of the participants showed mild to severe depressive BDI scores. Late chronotypes had a higher BDI(as) than intermediate and early types, which was independent of whether or not the participants were smokers. Both chronotype and BDI(as) correlated positively with social jetlag. BDI(as) was significantly higher in subjects with >2?h of social jetlag than in the rest of the population?again independent of smoking status. We also compared chronotype and social jetlag distributions between BDI categories (no symptoms, minimal symptoms, and mild to severe symptoms of depression) separately for men and women and for four age groups; specifically in the age group 31?40 yrs, subjects with mild to severe BDI scores were significantly later chronotypes and suffered from higher social jetlag. Our results indicate that misalignment of circadian and social time may be a risk factor for developing depression, especially in 31- to 40-yr-olds. These relationships should be further investigated in longitudinal studies to reveal if reduction of social jetlag should be part of prevention strategies. (Author correspondence: karla.allebrandt@med.uni-muenchen.de ).
A substantial amount of research has been conducted in an effort to understand the impact of short-term (<48 hr) total sleep deprivation (SD) on outcomes in various cognitive domains. Despite this wealth of information, there has been disagreement on how these data should be interpreted, arising in part because the relative magnitude of effect sizes in these domains is not known. To address this question, we conducted a meta-analysis to discover the effects of short-term SD on both speed and accuracy measures in 6 cognitive categories: simple attention, complex attention, working memory, processing speed, short-term memory, and reasoning. Seventy articles containing 147 cognitive tests were found that met inclusion criteria for this study. Effect sizes ranged from small and nonsignificant (reasoning accuracy: g = -0.125, 95% CI [-0.27, 0.02]) to large (lapses in simple attention: g = -0.776, 95% CI [-0.96, -0.60], p < .001). Across cognitive domains, significant differences were observed for both speed and accuracy; however, there were no differences between speed and accuracy measures within each cognitive domain. Of several moderators tested, only time awake was a significant predictor of between-studies variability, and only for accuracy measures, suggesting that heterogeneity in test characteristics may account for a significant amount of the remaining between-studies variance. The theoretical implications of these findings for the study of SD and cognition are discussed.
Despite its advantages as a chronobiological technique, the ultra-short sleep/wake protocol remains underutilized in circadian rhythm research. The purpose of this study was to examine circadian rhythms of psychomotor vigilance (PVT), mood, and sleepiness in a sample (n=25) of healthy young adults while they adhered to a 3 h ultra-short sleep/wake protocol. The protocol involved 1 h sleep intervals in darkness followed by 2 h wake intervals in dim light, repeated for 50-55 h. A 5 min PVT test was conducted every 9 h with the standard metrics of mean reaction time (RT; RT(mean)), median RT (RT(med)), fastest 10% of responses (RT(10fast)), and reciprocal of the 10% slowest responses (1/RT(10slow)). Subjective measures of mood and sleepiness were assessed every 3 h. A cosine fit of intra-aural temperature, assessed three times per wake period, established the time of the body temperature minimum (T(min)). Mood, sleepiness, and PVT performances were expressed relative to individual means and compared across eight times of day and twelve 2 h intervals relative to T(min). Significant time-of-day and circadian patterns were demonstrated for each of the PVT metrics, as well as for mood and sleepiness. Most mood subscales exhibited significant deterioration in day 2 of the protocol without alteration of circadian pattern. However, neither sleepiness nor performance was worse on the second day of observation compared to the first day. These data provide further support for the use of the ultra-short sleep/wake protocol for measurement of circadian rhythms.
The ability to generate torque during a maximum voluntary contraction (MVC) changes over the day. The present experiments were designed to determine the influence of an individual's chronotype on this diurnal rhythm and on cortical, spinal, and peripheral mechanisms that may be related to torque production. After completing a questionnaire to determine chronotype, 18 subjects (9 morning people, 9 evening people) participated in 4 data collection sessions (at 09:00, 13:00, 17:00, and 21:00) over 1 day. We used magnetic stimulation of the cortex, electrical stimulation of the tibial nerve, electromyographic (EMG) recordings of muscle activity, and isometric torque measurements to evaluate the excitability of the motor cortex, the spinal cord, and the torque-generating capacity of the triceps surae (TS) muscles. We found that for morning people, cortical excitability was highest at 09:00, spinal excitability was highest at 21:00, and there were no significant differences in TS EMG or torque produced during MVCs over the day. In contrast, evening people showed parallel increases in cortical and spinal excitability over the day, and these were associated with increased TS EMG and MVC torque. There were no differences at the level of the muscle over the day between morning and evening people. We propose that the simultaneous increases in cortical and spinal excitability increased central nervous system drive to the muscles of evening people, thus increasing torque production over the day. These differences in cortical excitability and performance of a motor task between morning and evening people have implications for maximizing human performance and highlight the influence of chronotype on an individual's diurnal rhythms.
Background
The aim of this study was to examine individual differences in a large sample of complete melatonin profiles not suppressed by light and search for possible associations between the amount and timing of melatonin secretion and a multitude of lifestyle variables. The melatonin profiles were derived from saliva samples collected every 30 minutes in dim light from 85 healthy women and 85 healthy men aged 18–45 years. There was a large individual variability in the amount of melatonin secreted with peak values ranging from 2 to 84 pg/ml. The onset of melatonin secretion ranged from 18:13 to 00:26 hours. The use of hormonal birth control, reduced levels of employment, a smaller number of days on a fixed sleep schedule, increased day length and lower weight were associated with an increased amplitude of melatonin secretion. The use of hormonal birth control, contact lenses, a younger age, and lower ratings of mania and paranoia were associated with a longer duration of melatonin secretion. An earlier occurrence of the onset of melatonin secretion was associated with an earlier wake time, more morningness and the absence of a bed partner. Lifestyle and behavioral variables were only able to explain about 15% of the individual variability in the amount of melatonin secretion, which is likely because of a substantial genetic influence on the levels of melatonin secretion.
Sleep in depressed patients resembles sleep in normal subjects whose circadian rhythms of temperature and rapid-eye-movement
sleep are phase-advanced (shifted earlier) relative to their sleep schedules. If this analogy is relevant to the pathophysiology
of depressive illness, advancing the time of sleep and awakening should temporarily compensate for the abnormal timing of
depressed patients' circadian rhythms. Four of seven manic-depressive patients studied longitudinally spontaneously advanced
their times of awakening (activity onset) as they emerged from the depressive phase of their illness. In a phase-shift experiment,
a depressed manic-depressive woman was twice brought out of depression for 2 weeks by advancing her sleep period so that she
went to sleep and arose 6 hours earlier than usual. The antidepressant effect of the procedure was temporary and similar in
duration to circadian desynchronization induced by jet lag in healthy subjects. This result supports the hypothesis that abnormalities
of sleep patterns in some types of depression are due to abnormal internal phase relationships of circadian rhythms.
The development and use of a new scale, the Epworth sleepiness scale (ESS), is described. This is a simple, self-administered questionnaire which is shown to provide a measurement of the subject's general level of daytime sleepiness. One hundred and eighty adults answered the ESS, including 30 normal men and women as controls and 150 patients with a range of sleep disorders. They rated the chances that they would doze off or fall asleep when in eight different situations commonly encountered in daily life. Total ESS scores significantly distinguished normal subjects from patients in various diagnostic groups including obstructive sleep apnea syndrome, narcolepsy and idiopathic hypersomnia. ESS scores were significantly correlated with sleep latency measured during the multiple sleep latency test and during overnight polysomnography. In patients with obstructive sleep apnea syndrome ESS scores were significantly correlated with the respiratory disturbance index and the minimum SaO2 recorded overnight. ESS scores of patients who simply snored did not differ from controls.
Bright light has recently been shown to have phase-shifting effects on human circadian rhythms. In this study we applied this effect to 20 patients with delayed sleep phase syndrome (DSPS) who were unable to fall asleep at conventional clock times and had a problem staying alert in the morning. In a controlled treatment study, we found that 2 h of bright light exposure in the morning together with light restriction in the evening successfully phase advanced circadian rhythms of core body temperature and multiple sleep latencies in these patients. This finding corroborates the importance of light for entraining human circadian rhythms.
Seasonal affective disorder (SAD) is a syndrome characterized by recurrent depressions that occur annually at the same time each year. We describe 29 patients with SAD; most of them had a bipolar affective disorder, especially bipolar II, and their depressions were generally characterized by hypersomnia, overeating, and carbohydrate craving and seemed to respond to changes in climate and latitude. Sleep recordings in nine depressed patients confirmed the presence of hypersomnia and showed increased sleep latency and reduced slow-wave (delta) sleep. Preliminary studies in 11 patients suggest that extending the photoperiod with bright artificial light has an antidepressant effect.
Clinical practice related to sleep problems and sleep disorders has been expanding rapidly in the last few years, but scientific research is not keeping pace. Sleep apnea, insomnia, and restless legs syndrome are three examples of very common disorders for which we have little biological information. This new book cuts across a variety of medical disciplines such as neurology, pulmonology, pediatrics, internal medicine, psychiatry, psychology, otolaryngology, and nursing, as well as other medical practices with an interest in the management of sleep pathology. This area of research is not limited to very young and old patients-sleep disorders reach across all ages and ethnicities. Sleep Disorders and Sleep Deprivation presents a structured analysis that explores the following: Improving awareness among the general public and health care professionals. Increasing investment in interdisciplinary somnology and sleep medicine research training and mentoring activities. Validating and developing new and existing technologies for diagnosis and treatment. This book will be of interest to those looking to learn more about the enormous public health burden of sleep disorders and sleep deprivation and the strikingly limited capacity of the health care enterprise to identify and treat the majority of individuals suffering from sleep problems. © 2006 by the National Academy of Sciences. All rights reserved.
Endogenous circadian rhythms in physiology and behavior are ubiquitous among mammals and are regulated by a master circadian clock, the suprachiasmatic nucleus of the hypothalamus. These intrinsic circadian rhythms are synchronized by light, melatonin, and social or physical activity to the 24-hour external light and dark cycles. Circadian rhythm sleep disorders (CRSD) occur when there is an alteration of the internal circadian timing mechanisms or a misalignment between the timing of sleep and the 24-hour social and physical environments. CRSDs, such as delayed sleep phase, advanced sleep phase and shift work sleep disorder, are often under-recognized, yet should be considered in the differential of patients presenting with symptoms of insomnia and/or hypersomnia. Because behavioral and environmental factors often are involved in the development and maintenance of these disorders, a multimodal treatment approach that combines behavioral and/or pharmacologic approaches is usually required. In addition to good sleep habits, timed exposure to bright light and melatonin can be used for the treatment of CRSD. Rapid advances in understanding the physiologic, cellular, and molecular basis of circadian rhythm and sleep regulation will likely lead to improved diagnostic tools and treatments for CRSDs.
Circadian rhythms, among other factors, have been shown to regulate key physiological processes involved in athletic performance [1-7]. Personal best performance of athletes in the evening was confirmed across different sports [8-12]. Contrary to this view, we identified peak performance times in athletes to be different between human "larks" and "owls" (also called "morningness/eveningness types" [13] or "chronotypes" [14] and referred to as circadian phenotypes in this paper), i.e., individuals with well-documented genetic [15-20] and physiological [21-24] differences that result in disparities between their biological clocks and how they entrain to exogenous cues, such as the environmental light/dark cycle and social factors. We found time since entrained awakening to be the major predictor of peak performance times, rather than time of day, as well as significant individual performance variations as large as 26% in the course of a day. Our novel approach combining the use of an athlete-specific chronometric test, longitudinal circadian analysis, and physical performance tests to characterize relevant sleep/wake and performance parameters in athletes allows a comprehensive analysis of the link between the circadian system and diurnal performance variation. We establish that the evaluation of an athlete's personal best performance requires consideration of circadian phenotype, performance evaluation at different times of day, and analysis of performance as a function of time since entrained awakening. VIDEO ABSTRACT:
Copyright © 2015 Elsevier Ltd. All rights reserved.
Significance
The use of light-emitting electronic devices for reading, communication, and entertainment has greatly increased recently. We found that the use of these devices before bedtime prolongs the time it takes to fall asleep, delays the circadian clock, suppresses levels of the sleep-promoting hormone melatonin, reduces the amount and delays the timing of REM sleep, and reduces alertness the following morning. Use of light-emitting devices immediately before bedtime also increases alertness at that time, which may lead users to delay bedtime at home. Overall, we found that the use of portable light-emitting devices immediately before bedtime has biological effects that may perpetuate sleep deficiency and disrupt circadian rhythms, both of which can have adverse impacts on performance, health, and safety.
Objectives
To investigate the independent effects of depression and subtypes of anxiety on insomnia, and vice-versa, and the independent effect of chronotype on insomnia, depression, and subtypes of anxiety.
Methods
In all, 318 South Australian high school students from grades 7 to 11 (age range, 12–18 years; mean, 14.97 ± 1.34) participated in this cross-sectional study. Validated self-report questionnaires were used to assess insomnia, depression, subtypes of anxiety, and chronotype.
Results
After confounder variables were controlled, insomnia predicted depression and panic disorder (PD), whereas insomnia was predicted by depression and generalized anxiety disorder (GAD). Obsessive–compulsive disorder (OCD), separation anxiety (SAD), and social phobia (SP) were not significantly related to insomnia. Eveningness predicted the models in which depression and PD predicted insomnia and vice-versa. Eveningness also predicted the models in which insomnia was predicted by OCD, SAD, and SP.
Conclusions
Insomnia independently predicts depression and is predicted by depression and GAD, but not other forms of anxiety. The independent prediction of insomnia on PD is unlikely to be clinically significant. Chronotype independently predicts insomnia and depression, but not subtypes of anxiety. Theoretical and clinical implications are discussed.
Numerous ocular parameters have been proposed as reliable physiological markers of drowsiness. A device that measures many of these parameters and then combines them into a single metric (the Johns Drowsiness Scale [JDS]) is being used commercially to assess drowsiness in professional drivers. Here, we examine how these parameters reflect changes in drowsiness, and how they relate to objective and subjective indices of the drowsy state in a controlled laboratory setting.
A within subject prospective study.
29 healthy adults (18 males; mean age 23.3 ± 4.6 years; range 18-34 years).
N/A.
Over the course of a 30-h extended wake vigil under constant routine (CR) conditions, participants were monitored using infrared reflectance oculography (Optalert) and completed bi-hourly neurobehavioral tests, including the Karolinska Sleepiness Scale (KSS) and Psychomotor Vigilance Task (PVT). Ocular-defined increases in drowsiness were evident with extended time awake and during the biological night for all ocular parameters; JDS being the most sensitive marker of drowsiness induced by sleep regulatory processes (p < 0.0001). In addition, the associations between JDS in the preceding 10-min period and subsequent PVT lapses and KSS were stronger (AUC 0.74/0.80, respectively) than any other ocular metric, such that PVT lapses, mean response time (RT), and KSS increased in a dose-response manner as a function of prior JDS score (p < 0.0001).
Ocular parameters captured by infrared reflectance oculography detected fluctuations in drowsiness due to time awake and during the biological night. The JDS outcome was the strongest predictor of drowsiness among those tested, and showed a clear association to objective and subjective measures of drowsiness. Our findings indicate this real-time objective drowsiness monitoring system is an effective tool for monitoring changes in alertness and performance along the alert-drowsy continuum in a controlled laboratory setting.
Anderson C; Chang AM; Sullivan JP; Ronda JM; Czeisler CA. Assessment of drowsiness based on ocular parameters detected by infrared reflectance oculography. J Clin Sleep Med 2013;9(9):907-920.