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Bright light exposure during acute tryptophan depletion prevents a lowering of mood in mildly seasonal women
Abstract
We investigated the influence of bright light exposure on the mood-lowering effect of acute tryptophan depletion (ATD). Mildly seasonal healthy young women without a personal or family history of psychiatric disorders remained in either dim or bright light during two test days. Tryptophan-deficient and nutritionally balanced amino acid mixtures were administered in counterbalanced order. Mood state was assessed using the Profile of Mood States (POMS) and Visual Analogue Scales (VAS). In dim light, ATD decreased POMS scores across most subscales, indicating a worsening of mood. In bright light, mood was unaffected by ATD. Thus, bright light blocked the worsening of mood caused by ATD. This was also observed on the positive mood VAS. These results indicate a direct, immediate interaction between bright light and serotonin function. Bright light might help protect against ATD-induced mood change by increasing serotonin above the threshold level below which there is a lowering of mood.
... We recently conducted a within-group crossover study of ATD in a group of healthy never-depressed mildly seasonal women exposed to either bright light or dim light during test days. As hypothesized, ATD resulted in a lowering of mood only in participants exposed to dim light during test days; participants in the bright light condition showed no change in mood following ATD (aan het Rot et al., 2008 ). We suggested that bright light was able to prevent ATD's effect on mood by increasing serotonin above the threshold level below which there is a lowering of mood. ...
... Mood questionnaires, including the bipolar Profile of Mood States (POMS) (McNair et al., 1982 ), were administered in the evening before and in the morning of the test day, as well as five, six, seven, and 7.5 hours after amino acid mixture ingestion. Briefly, ATD caused a lowering of mood in the dim light group only (see aan het Rot et al. (2008) for more details). Blood samples were taken just before and 5.5 hours after amino acid ingestion. ...
... aan het Rot et al. (2008) previously reported a lowering of mood following ATD in participants assigned to dim light, but not in those assigned to bright light. Thus, we repeated the above analyses with mood state assessed just prior to the facial emotion expression recognition task (i.e. ...
In healthy never-depressed individuals, acute tryptophan depletion (ATD) may selectively decrease the accurate recognition of fearful facial expressions. Here we investigated the perception of facial emotions after ATD in more detail. We also investigated whether bright light, which can reverse ATD's mood-lowering effect, can also reverse its effect on the perception of facial emotions. On two separate test days, spent in a room that was either bright (n = 14) or dim (n = 16), healthy never-depressed women completed a facial emotion perception task six hours after ingesting tryptophan-deficient and balanced amino acid mixtures. Treatments were administered double blind and in randomized order using a crossover design. In dim light ATD decreased recognition accuracy of anger, disgust, and surprise. The labeling of fear and sadness was not affected. In bright light no effects of ATD were seen. Bright light was identified as a potential confounding factor in task performance. The effects of ATD on facial emotion perception may be less emotion-specific than thought previously, and occurred in a direction opposite to what might be expected based on theories of mood-congruent bias.
... A possible effect of light on mood suggests it might also influence behaviour. We have shown that tryptophan, the precursor of serotonin, improves social behaviour along an agreeable-quarrelsome dimension in healthy people (aan het Rot et al., 2006b;Moskowitz et al., 2001). An event-contingent recording method was used which provides reliable estimates of behaviour when data are aggre-gated over a suitable number of days (Moskowitz, 1994). ...
... An event-contingent recording method was used which provides reliable estimates of behaviour when data are aggre-gated over a suitable number of days (Moskowitz, 1994). Based on recent observations in healthy volunteers that bright light exposure may affect the serotonin system within a few hours (aan het Rot et al., 2006a;Lambert et al., 2002), the present study was designed on the premise that the effects of light on everyday social behaviour and mood would resemble those of tryptophan. In mildly seasonal healthy individuals, who are sensitive to seasonal changes in natural light levels without suffering from winter depressions, ambient light levels and social interactions were measured across 20-day periods in winter and summer. ...
... Bright light may increase brain serotonin synthesis. There were similarities between the known effects of tryptophan, which increases brain serotonin synthesis, on social interaction (aan het Rot et al., 2006b;Moskowitz et al., 2001) and the identified effects of bright light on social interaction. Our hypothesis that bright light exposure might affect communal behaviours and mood in a way similar to tryptophan was confirmed. ...
Bright light is used to treat winter depression and might also have positive effects on mood in some healthy individuals. We examined possible links between bright light exposure and social interaction using naturalistic data. For 20 days in winter and/or summer, 48 mildly seasonal healthy individuals wore a light meter at the wrist and recorded in real-time their behaviours, mood, and perceptions of others during social interactions. Possible short-term effects of bright light were examined using the number of minutes, within any given morning, afternoon or evening, that people were exposed to light exceeding 1000 lux (average: 19.6min). Social interactions were labelled as having occurred under conditions of no, low or high bright light exposure. Independent of season, day, time, and location, participants reported less quarrelsome behaviours, more agreeable behaviours and better mood when exposed to high but not low levels of bright light. Given that the effects were seen only when exposure levels were above average, a minimum level of bright light may be necessary for its positive effects to occur. Daily exposure levels were generally low in both winter and summer. Spending more time outdoors and improving indoor lighting may help optimize everyday social behaviour and mood across seasons in people with mild seasonality.
... Individuals with seasonal affective disorder (SAD) experience impairments in mood, sleep, energy, appetite, and social functioning (Kasper et al., 1989;Rosenthal et al., 1984b). Bright light exposure can reverse these symptoms, normalising mood and enhancing agreeableness (aan het Rot et al., 2008;Kasper et al., 1989;Rosenthal et al., 1984b). The alterations in mood and social functioning might be related in part to changes in emotional facial recognition. ...
... The a priori determined sample size of 15 participants in each light group (dim, bright) would allow the detection of a main treatment difference of approximately 0.8 SD with a power of 80% when alpha is 0.05. For comparison purposes, the study was carried out in women as in a previous study using the acute tryptophan depletion method (aan het Rot et al., 2008Rot et al., , 2010. The power to measure the treatment by group interaction was expected to be the same as the power to measure the treatment effect because both effects were studied within subjects. ...
Bright light can affect mood states and social behaviours. Here, we tested potential interacting effects of light and dopamine on facial emotion recognition. Participants were 32 women with subsyndromal seasonal affective disorder tested in either a bright (3000 lux) or dim light (10 lux) environment. Each participant completed two test days, one following the ingestion of a phenylalanine/tyrosine-deficient mixture and one with a nutritionally balanced control mixture, both administered double blind in a randomised order. Approximately four hours post-ingestion participants completed a self-report measure of mood followed by a facial emotion recognition task. All testing took place between November and March when seasonal symptoms would be present. Following acute phenylalanine/tyrosine depletion (APTD), compared to the nutritionally balanced control mixture, participants in the dim light condition were more accurate at recognising sad faces, less likely to misclassify them, and faster at responding to them, effects that were independent of changes in mood. Effects of APTD on responses to sad faces in the bright light group were less consistent. There were no APTD effects on responses to other emotions, with one exception: a significant light × mixture interaction was seen for the reaction time to fear, but the pattern of effect was not predicted a priori or seen on other measures. Together, the results suggest that the processing of sad emotional stimuli might be greater when dopamine transmission is low. Bright light exposure, used for the treatment of both seasonal and non-seasonal mood disorders, might produce some of its benefits by preventing this effect.
... ATD may also worsen mood in healthy women (Ruhe et al., 2007). Two studies have found that bright light exposure during ATD can prevent this mood worsening (aan het Rot et al., 2008;Defrancesco et al., 2013). Importantly, as both studies lasted only several hours, bright light exposure can apparently have fairly immediate effects on mood. ...
... Nonetheless, we found a significant effect of the light therapy session on mood. Thus, as previously suggested (aan het Rot et al., 2008;Defrancesco et al., 2013), bright light exposure can lead to rapid mood improvement even in non-clinical samples and at a relatively moderate light intensity. ...
To examine whether acute changes in cognitive empathy might mediate the impact of light therapy on mood, we assessed the effects of a single light-therapy session on mood and cognitive empathy in 48 premenstrual women, including 17 who met Premenstrual Symptoms Screening Tool criteria for moderate-to-severe premenstrual syndrome / premenstrual dysphoric disorder (PMS/PMDD). Using a participant-blind between-groups design, 23 women underwent 30 minutes of morning light therapy (5000 lx; blue-enriched polychromatic light, 17000 K) while 25 women had a sham session (200 lx, polychromatic light, 5000 K). We administered the Positive Affect and Negative Affect Schedule and the Affect Grid right before and after the intervention, and 60 minutes later upon completion of a computerized empathic accuracy task. There were no significant effects of light condition on cognitive empathy as assessed using the computer task. Nonetheless, bright light reduced negative affect, specifically in women not using hormonal contraceptives. No effects of bright light on mood were observed in women who were using contraceptives. If a single light-therapy session does not alter cognitive empathy, then cognitive empathy may not mediate the impact of light therapy on mood in premenstrual women.
... nausea, vomiting, dizziness, and sweating (48), were included in this questionnaire (the entire questionnaire is available in the Supplementary file). Participants completed this questionnaire every hour and immediately before and after the intake of the AA beverages. ...
... In the separated item analyses, nausea is the only side effect showing a main effect of time and displays an equal development. Although few ATD studies focused on the examination of side effects, nausea appears to be a frequent problem in these particular studies (31,48). It is very likely that the ingestion of a substantial amount of crystalline AAs (Moja-De: 6.5 g/10 kg body weight, ATD PHE/LEU 6.2 g/10 kg body weight) that remain in the stomach until dissolution in the acidic environment contributed to the reports of nausea (57). ...
Background
Acute tryptophan depletion (ATD) is a well-established dietary method in translational brain research used to briefly lower central nervous serotonin (5-hydroxytryptamine (5-HT)) synthesis. A simplified two amino acid ATD formula (ATDPHE/LEU) was developed while reducing the overall amount of amino acids (AAs), with the objective of administration especially in children and adolescents in future studies.
Objective
This study investigated tryptophan (TRP) influx rates across the blood-brain barrier (BBB) after dietary ATDPHE/LEU administration relative to the ATD Moja-De protocol that has been established for use in children and adolescents.
Design
Seventy-two healthy adults (50% females) were randomized into four groups and administered ATD Moja-De, its TRP-balanced control condition (BAL), ATDPHE/LEU, or its respective control mixture (BALPHE/LEU) in a counterbalanced, double-blind, between-subjects design. Blood samples were collected at baseline and at hourly intervals for 6 h after AA intake. Questionnaires about mood, taste, and challenge tolerance were completed at fixed time points.
Results
Both challenge mixtures significantly reduced central nervous TRP influx as calculated by Michaelis–Menten kinetics relative to baseline and the respective control conditions with only mild and comparable side effects. A greater decline in TRP influx over the BBB after ATDPHE/LEU administration when compared with ATD Moja-De was detected without group effects for taste, challenge tolerance, and mood. There was unintended initial short increase in plasma TRP concentrations observed after ATDPHE/LEU intake, and a possible redistribution between free and protein-bound TRP triggered by protein synthesis stimulated by the ingested AAs may account for this finding. Moreover, a decline in TRP influx after BALPHE/LEU administration over a 6-h period was observed, and the large amount of PHE in the BALPHE/LEU mixture may be a possible explanation for this particular phenomenon, which could have led to an unexpected increase in displacement of TRP at the BBB in this control condition.
Conclusions
This pilot study provides preliminary evidence for the possibility of lowering TRP influx as calculated by Michaelis–Menten kinetics into the brain by using a simplified ATD protocol in humans. The simplified composition of only two AAs, the lower overall AA amount, and the appropriate tolerance are characteristics of the newly developed ATDPHE/LEU protocol. Future studies focusing on the effects of the ATDPHE/LEU protocol and its respective control condition on CSF 5-HIAA concentrations, as well as neurochemical studies in rodents, are needed to further validate this newly developed AA mixture before definite conclusions about its usability in ATD-related research in humans, its specificity, and additional effects can be made.
... Moreover, bright light induces direct responses in alertness-related subcortical structures (hypothalamus, brainstem, thalamus) limbic areas (amygdale and hippocampus), and even in cortical areas (Vandewalle, Maquet, & Dijk, 2009). Furthermore, effects on brain serotonin turnover have been proposed to run through retinal light exposure (aan het Rot, Benkelfat, Boivin, & Young, 2008a). This implies that, in addition to entraining the biological clock, light shows immediate effects on alertness, cognitive performance, and even affective responses (Vandewalle et al., 2009). ...
... Similarly, oral intake of vitamin D supplements during winter has been found to increase positive affect (Landsdowne & Provost, 1998). Besides effects on serotonin production by sunlight touching the skin, it has also been proposed that retinal exposure to bright light can increase brain serotonin production (aan het Rot et al., 2008a). ...
Both nature and daylight have been found to positively influence health. These findings were, however, found in two separate research domains. This paper presents an overview of effects found for daylight and nature on health and the health-related concepts stress, mood, and executive functioning and self-regulation. Because of the overlap in effects found and the co-occurrence of both phenomena, the paper points to the need to consider daylight factors when investigating effects of nature and vice versa. Furthermore, the existence of possibly shared underlying mechanisms is discussed and the need to unify the research paradigms and dependent variables used between the two research fields. Last, in view of the beneficial effects of both phenomena on health, our objective is to raise awareness amongst the general public, designers, and health practitioners to use these naturally available phenomena to their full potential.
... However, the post-encephalitic brain exhibits a 5× hypersensitivity to psychotropic and neuropsychiatric drugs [33,57], suggesting that any drug being repurposed for long-COVID, including melatonin and selective serotonin reuptake inhibitors (SSRIs) [58], could be problematic [59,60]. Alternatively, LT is minimally invasive and elevates serotonin and its precursor tryptophan [61], suggesting that this may be the mechanism underlying the therapeutic effect seen in the present findings. It has been suggested further that melatonin could be employed in a dual role as an antiinflammatory and to repair disrupted circadian phase [62] in patients with long-COVID [53][54][55]. ...
Background
In this case series, results from daily visual exposure to intense polychromatic light of 2000 to 4000 LUX is presented. Bright light treatment is a standard procedure for treating seasonal affective disorder and prodromal Parkinson’s disease with high success. With the post-encephalitic symptoms of long-COVID closely approximating those of prodromal Parkinson’s disease, we treated insomnia and sleep-related parameters in these patients, including total sleep, number of awakenings, tendency to fall back to sleep, and fatigue, to determine whether mending sleep could improve quality of life.
Case presentation
We present three female and two male Caucasian patients aged 42–70 years with long-COVID that persisted from 12 weeks to 139 weeks after contracting coronavirus disease.
Conclusion
A light presentation protocol was adapted for long-COVID that not only restored sleep in all patients, but also unexpectedly repaired the depression, anxiety, and cognitive changes (brain fog) as well. A robust pattern of recovery commencing 4–5 days after treatment and was maintained for weeks to months without relapse. These preliminary findings represent a novel, minimally invasive approach for managing the most debilitating symptoms of long-COVID, making it an ideal candidate for the drug hypersensitive, post-encephalitic brain. That a compromised circadian mechanism seen in Parkinson’s disease may also underlie post-encephalitic long-COVID implicates a compromised role of the circadian system in these disorders.
... Similarly, increased light exposure during daytime can modulate cognitive brain functioning such as logical reasoning and creative thinking [83]. Research has found that periods of bright light exposure (greater than 1000 lux) during daytime can lead to better mood and to social interactions that are less quarrelsome and more co-operative [84] which may be associated with the effect of bright light on serotonin metabolism [85]. ...
Today, people spend 90% or more of their lives indoors. It is therefore imperative that their health and well-being is considered a priority in architectural design. Daylight, its availability and spectral characteristics have recently taken a more prominent role in design. Today, daylight design is trans-disciplinary and must not only consider energy performance, visual task and comfort but also matters of health and well-being. The discovery of the intrinsically photosensitive Retina Ganglion Cell (ipRGC) and subsequent findings suggest a much wider role for daylight in delivering healthy buildings.
The human circadian system is known to be responsible for the temporal regulation, over approximately 24 hours, of a range of physiological processes and drives the rhythms of body temperature, hormone secretion and metabolism. Published research on circadian physiology has demonstrated that the impact of light on the human circadian system depends on its intensity, spectrum, spatial distribution, timing, duration, pattern and photic history. The primary environmental stimulus to this system is light exposure to the eye. The internal human body clock requires environmental cues to synchronise to the day/night solar cycle on a regular basis so as to avoid imbalances in the circadian system that have been shown to have negative health and well-being consequences.
A considerable body of research is now providing insights to the many potential implications of good and bad lighting design decisions, but much of this has focused on visual physiology and non-image forming (NIF) issues. What is less often considered is the nature of the spectral microclimate, i.e. that environment whose specific characteristics resolve to directly influence the spectral properties of light which, in turn, affect the occupants' circadian system and the entrainment potential of a typical microclimate.
Research has begun to identify the most influential design parameters on the circadian entrainment potential of a microclimate. Most findings are based on computer simulations and those that have studied the effects under real daylight conditions are very few and limited. As a result, very little is known about the specific spectral nature of daylight in real settings.
This research undertook to study the effect of a specific range of design variables on circadian entrainment under real daylight conditions. The research developed and employed a novel monitoring system consisting of five spectrometers (four internal views and one external) to measure the spectral environment of a scale model using four internal wall colour finishes from four view perspectives. A dataset of 2,689 reading sets was generated to represent the modelled scenario under 11 sky conditions for each hour of the day, between 08:00 and 17:00, in four view directions (1,584 individual configurations) and under three possible sun conditions.
The analysis of the dataset involved both the results of monitoring and an assessment of the metrics available. In addition to existing and widely used metrics, a number of additional relationships were proposed to support both analysis and interpretation. It was found that the use of more than one metric was typically needed to make more revealing interpretations of the data. It was also found that even with a relatively modest number of variables, the spectral interaction between daylight and the modelled space was complex and, at times, challenging to represent.
Under daylight conditions, variations in sky type resulted in only modest changes to melanopic and photopic spectral irradiance. It was shown that, in the absence of the direct solar component, there were only modest changes to the melanopic content of daylight, decreasing as cloud cover increased. The direct solar component produced a very different result, dominating in both intensity and spectral character but also relatively static in its spectral properties. These characteristics translated directly into the internal microclimate where other variables played a more significant role in modifying the spectral properties. Of these, the chosen wall colours were the most impactful, exemplified by their respective spectral reflectance profiles. These, together with the total area of wall available to reflect irradiance and the extent to which the window was visible from each respective sensor, had a defining influence on the measured spectral profiles.
... sunlight) is a standard treatment for seasonal affective disorder (SAD), and its efficacy has been related to its ability to increase brain serotonin level (Pail et al. 2011). Evidence supporting bright light's serotonin boosting effect includes (Young 2007), 1) its comparable efficacy to fluoxetine (an SSRI) in relieving depression in SAD patients (Lam et al. 2006), 2) its ability to reverse the mood-lowering effect induced by tryptophan (precursor of serotonin) depletion (Aan Het Rot et al. 2008), and, 3) a positive correlation between duration of sunlight exposure and brain serotonin synthesis rate in a group of Australians (Lambert et al. 2002). ...
We examined whether sunlight affects hot flushes in working menopausal women and explored effect modification by shift work and season. In this prospective cohort study, daily hot flush score (outcome) was measured by the 7-day North Central Cancer Treatment Group Daily Vasomotor Symptoms Diary. Daily duration of sunlight (≥2000 lux) was recorded by the HOBO MX2202 pendant. Both variables were measured in two 7-day data collection phases. T0 data were collected during the Australian Summer (December 2017, January and February 2018); and T1 data were collected in the Australian winter (June, July and August 2018). Linear mixed effects model was used. Shift work and season were both confounders and effect modifiers. To detect a median effect size of R² = 0.2, 34 women were required to achieve an effective sample size of 41. A total of 49 menopausal women were recruited, 11 shift and 38 day workers. Some 13 women had various missing observations. For shift workers, an hour increase in sunlight exposure was associated with a 1.4-point reduction in hot flush score (p = .016). This relationship was not significant for day workers (p = .185). The finding of this study suggests increased sunlight exposure might improve hot flushes in menopausal shift workers who are moderately bothered by hot flushes, but probably not in day workers. The possible role of shift-work associated circadian disruption on estrogen level in regard to elevated intensity and frequency of hot flush in menopausal women is discussed.
... Serotonin has been linked with seasonal affective disorder through higher levels of serotonin reuptake (resulting in decreased synaptic levels) during the autumn and winter months (Vadnie 2017). In an experimental study, aan het Rot et al (2008) showed that lower levels of mood induced by depleting a precursor of serotonin (tryptophan) were largely blocked by exposure to bright light. (See Table 1 for an overview of two concurrent neurophysiological processes involved in bright light therapy.) ...
Bright light therapy is an accepted and commonly used treatment for seasonal affective and circadian rhythm disorders. In the past 20 years, researchers have examined the effectiveness of bright light therapy in improving depression and agitation in older adults with dementia. This article provides clinicians with a summary of the neurophysiology of bright light therapy, bright light research considerations, an evidence-based bright light protocol, problems related to bright light therapy, and clinical implications for bright light therapy in older adults with dementia. Bright light exposure is a safe, non-pharmacological treatment that is currently underutilised in this population. Clinicians may find bright light therapy beneficial as a primary or adjunctive treatment in reducing depression and agitation in older adults with dementia.
... Non-pharmacological methods to increase brain serotonin may not only improve the mood and social functioning of healthy people but also allow verifying the idea that increases in brain serotonin can help protect people against the onset of various disorders both mental and physical. In a recent study, meditation has been able to increase the release of dopamine Perreau-Linck et al. [47][48][49][50]. The study, the first also to point out that self-induced mood changes may affect serotonin synthesis. ...
... [18] Studies show that the mice suffering from the lack of Serotonin may experience lower growth; further, they show respiratory, cardiovascular problems, sleep disorder, and intensified aggressive behaviors. [19] Burns et al. reviewed the evidence demonstrating that G. biloba directly and indirectly influences cholinergic systems through regulating serotonergic system. [20] On the other hand, there are two monoamine oxidase enzymes in neurons and astroglia oxidizing monoamines such as epinephrine, norepinephrine, dopamine, and serotonin. ...
Midwifery is a high-stressed job, and midwiferies are prone to many stresses threatening their health over long working hours; further, it also influences their ability and the quality of patient care. Midwifery is characterized with sleep disorder influenced by stress and working shifts. This research is conducted to study the effect of Ginkgo biloba on midwiferies sleep quality in hospitals. In this random controlled clinical trial, thirty midwiferies working in hospitals were assigned into two groups of receiving treatment and placebo. The participants suffering from sleep disorder received the packs containing G. biloba and/or placebo and a pill every 12 h was prescribed over 30 days. Demographic and Pittsburgh Sleep Quality Index questionnaire were distributed prior and after Ginkgo. Following a 1-week cleaning, Ginkgo group received placebo; while, the placebo received Ginkgo over 30 days. Pittsburgh Sleep Quality Index questionnaire was also completed at the beginning and end of this period. Data were collected and descriptive, and inferential statistics was analyzed by t-test, Anova test through SPSS-20. At significant level P = 0.457, it may be expressed that there is no significant difference seen in the total sleep quality following treatment in experimental and control group. Research results demonstrate that Ginkgo has no effect on sleep quality of working midwiferies. Therefore, it is necessary to conduct longer studies with larger sample volumes. © 2017 Annals of Tropical Medicine and Public Health | Published by Wolters Kluwer-Medknow.
... In patients successfully treated with BLT and in remission, depletion of tryptophan, the amino acid precursor of serotonin, reversed the effects of BLT on mood [46,47]. In addition, the mood lowering effect of tryptophan depletion is blocked under bright light conditions [48] again supporting the notion that BLT affects serotonergic neurotransmission. Since alterations in tryptophan [49] and the hypothalamic pituitary adrenal (HPA) axis activity [50,51] during pregnancy have been implicated in serotonin dysregulation and PND, this provides a possible rationale for the application of BLT in PND. ...
Background
Perinatal depression (PND) has an overall estimated prevalence of roughly 12 %. Untreated PND has significant negative consequences not only on the health of the mothers, but also on the physical, emotional and cognitive development of their children. No certain risk factors are known to predict PND and no completely safe drug treatments are available during pregnancy and breastfeeding. Sleep and depression are strongly related to each other because of a solid reciprocal causal relationship. Bright light therapy (BLT) is a well-tested and safe treatment, effective in both depression and circadian/sleep disorders. Methods
In a 3-year longitudinal, observational, multicentre study, about 500 women will be recruited and followed-up from early pregnancy (10–15 gestational week) until 12 months after delivery. The primary aim of the present study is to systematically explore and characterize risk factors for PND by prospective sleep assessment (using wrist actigraphy, polysomnography and various sleep questionnaires) and bloodbased analysis of potential markers during the perinatal period (Life-ON study). Secondary aims are to explore the relationship between specific genetic polymorphisms and PND (substudy Life-ON1), to investigate the effectiveness of BLT in treating PND (substudy Life-ON2) and to test whether a short term trial of BLT during pregnancy can prevent PND (substudy Life-ON3). DiscussionThe characterization of specific predictive and risk factors for PND may substantially contribute to improve preventive medical and social strategies for the affected women. The study results are expected to promote a better understanding of the relationship between sleep disorders and the development of PND and to confirm, in a large sample of women, the safety and efficacy of BLT both in prevention and treatment of PND. Trial registrationClinicalTrials.gov NCT02664467. Registered 13 January 2016.
... depletion paradigm which reduces the bioavailability of serotonin in the brain as tryptophan is a precursor for serotonin synthesis. This evidence showed that administering BLT could prevent tryptophan depletion-mediated depression by directly interacting with serotonin function (aan het Rot et al., 2008). While combining the retrieved data in this meta-analysis, we observed a certain pattern regarding the duration of treatment. ...
Background:
Bright light therapy (BLT) is a well-established treatment for seasonal depression. In the last two decades, the interest in BLT has expanded to involve other nonseasonal types of depression. The role of BLT for nonseasonal depression remains unsettled. In view of the growing number of studies in this area, this review aimed to assess the efficacy of BLT in nonseasonal depression.
Methods:
We searched Pubmed; Scopus; PsychINFO; Evidence Based Medicine Guidelines and Cochrane Library until December 2015. The Standardized mean difference was calculated to assess the efficacy of BLT in nonseasonal depression. Data were subgrouped according to different study characteristics. Heterogeneity was assessed by examining the I(2) index.
Results:
Nine trials met the inclusion criteria. After employing the more conservative random-effects model, the overall model showed a significant reduction of depressive symptoms after BLT administration (SMD=-0.62, P<0.001, I(2)=37%). In particular, BLT appears to be efficacious when administered for 2-5 weeks (SMD=-0.78, P<0.001, I(2)=0%), and as monotherapy (SMD=-0.71, P<0.001, I(2)=18%). Studies of BLT for perinatal depression have found statistically insignificant improvement (SMD=-0.17, P>0.05, I(2)=44%).
Limitations:
The overall heterogeneity of the included trials was moderate. The participants were not adequately blinded to the intervention. The sample size was small for certain subgroups. The long-term effect of BLT on depression was not explored.
Conclusions:
BLT appears to be efficacious, particularly when administered for 2-5 weeks' duration and as monotherapy. There is an obvious need to optimize the duration and intensity of exposure, the timing and the duration of treatment sessions.
... The realization that mood and alertness might operate according to a separate pathway is comparatively new. Limited evidence, but consistent across methodologies, suggests that acute bright light exposure by day can inuence serotonin metabolism [aan het Rot et al. 2008], leading to improved mood and more cooperative social behaviours [aan het Rot et al. 2007]. The spectral sensitivity function of these effects is not known. ...
Our common experience is that windows are desirable; in recent years science has begun to explain why. The last reviews of this literature were published a decade ago; therefore, we felt the time to be right for a comprehensive review and for the development of a research agenda to move activity forward in directions that would have practical applications. The review identied three broad processes through which residential windows and skylights can affect people in their homes, for good and ill: visual processes , acting primarily through light detected at the retina by rods and cones; non-visual ocular processes , acting primarily through light detected at the retina by intrinsically photoreceptive retinal ganglion cells; and processes occurring in the skin. This qualitative review revealed that there is no shortage of research questions facing photobiologists, psychologists, architects, lighting designers and others in the broad lighting community.
... The authors suggested that an increase in mood in the majority of social interactions together with a small but significant increase in quarrelsomeness in some interactions may be an explanation for their findings. As bright light is thought to increase brain serotonin (aan het Rot et al., 2008), the results of the study by Hsu et al. (2014) are in line with the present results. ...
Background: Individuals with a family history of depression (FH+) show subtle abnormalities in the processing of social stimuli. This could negatively affect their interpersonal functioning and contribute to their depression risk. Repeated administration of the serotonin precursor tryptophan has previously been shown to increase agreeable behavior and reduce quarrelsome behavior in irritable people, who are also considered at risk for depression. Methods: To examine the effects of tryptophan on social functioning in FH+ individuals, 40 men and women with at least one first-degree relative with depression received tryptophan (1g TID) and placebo for 14 days each in a double-blind crossover design and recorded their social behavior and mood during everyday interpersonal encounters. Participants also provided daily ratings of their positive and negative cognitions concerning their social functioning. Results: Tryptophan improved mood. Unexpectedly, tryptophan increased quarrelsome behavior and reduced agreeable behavior, specifically during interactions at home. The behavioral effects of tryptophan were not moderated by mood, or by the interaction partner. Negative social cognitions were lower during tryptophan when tryptophan was given second and lower during placebo when placebo was given second. Conclusion: Overall, tryptophan may not alter social behavior in FH+ individuals as it does in irritable people. However, the behavioral effects of tryptophan at home might be seen as a way for FH+ individuals to achieve more control. Over time, this may positively influence the way they feel and think about themselves in a social context.
© The Author 2015. Published by Oxford University Press on behalf of CINP.
... Regarding the above information, when tryptophan is high, light exposure is normal and exercise is low or normal then serotonin will be high, also when tryptophan is high, light exposure is normal and exercise is high then serotonin level will be very high as illustrated in rules 15, 16, 17. The light therapy is used for mood disorder during acute tryptophan depletion [51], so the rules with high level of light have elevated serotonin. For instance if we have high level of light exposure, in rule number 6, an individual with low tryptophan, normal exercise will show normal serotonin level or in rule number 7 when tryptophan is low and exercise is high then serotonin level will be high. ...
According to the world health organization, major depressive disorder (MDD) is considered as the fourth main cause of death and premature weakness in the whole world. Abnormality in the neurotransmitters level is the one of the main factors which may result in this disorder. In this article serotonin is chosen among these neurotransmitters, which is the most implicated in the pathophysiology of the major depression and because the assessment of serotonin is of the crucial important, the fuzzy logic approach is described for making serotonin model. In this paper, three effective factors on serotonin are modeled by fuzzy logic. This model is only a part of our project which is performed for modeling of the major depression.
... Prior work has indicated that interventions which can increase levels of brain serotonin can help decrease quarrelsome behavior (aan het Rot, Moskowitz, Pinard, & Young, 2006;Moskowitz et al., 2001). Exposure to bright light appears to affect the serotonin system (aan het Rot, Benkelfat, Boivin, & Young, 2006;Lambert, Reid, Kaye, Jennings, & Esler, 2002) and exposure to even 20 minutes of natural bright light has been shown to decrease quarrelsome behavior (aan het Rot, Moskowitz, & Young, 2008). Workplace policies that support exposure to bright light may be helpful to reduce quarrelsome behavior. ...
We identify ‘‘quarrelsomeness’’ as an important component in understanding destructive behaviors
in organizational contexts. Quarrelsomeness has been studied both as a personality trait that
generalizes over occasions and situations and as a reflection of interpersonal processes that unfold
over time in association with event-specific cues. While a variety of studies have documented the
role of quarrelsomeness in explaining behavior in interpersonal contexts, a review of the literature
revealed few studies explicitly examining the influence of quarrelsomeness in organizational contexts.
As work contexts typically involve frequent interpersonal interactions, it is plausible to expect that
quarrelsomeness would be an influence on several organizationally relevant issues. The present article
examines quarrelsomeness as a trait related to organizational issues such as dysfunctional conflict
and workplace aggression, as a behavior that is likely to emerge in association with event-specific
cues, and as a moderator of the association between organizational factors and individuals’ behavioral
responses to these factors. Theoretical and practical implications are discussed.
... The necessary daily dose of light is still not known but several studies have shown that higher daytime light exposures (at least 1000 lux at eye level) or higher correlated colour temperature (at least 6500 K) go along with improved mood and task performance, higher subjective sleep quality and quality of social interactions and greater feelings of vitality. [51][52][53][54][55] From a methodological point of view productivity-related studies often suffer from low validity due to short-term light exposures, small sample sizes, simplified working tasks and the elimination of work organisation's influences on productivity measures. In contrast, this field study aimed at investigating short-term, long-term and seasonal effects of a dynamic ambient lighting scenario with blue-enriched light with increased illuminances on subjective, physiological and productivity-related measures under natural working conditions of a sleep-and lightdeprived shift work population (female permanent morning shift workers). ...
Permanent morning shift workers often suffer from impaired sleep and complain about increased fatigue during the day due to an early rising time in the morning. A controlled field investigation with female permanent morning shift workers was conducted, which evaluated the acute, monthly and seasonal psycho-physiological and productivity-related impacts of a dynamic ambient lighting scenario. Dynamic lighting had an acute psycho-physiological calming effect and positively influenced sleep latency and anxiety/depression ratings. Finally, productivity (decreased mean relative handling time) was increased during the winter. This field study contributes to the growing knowledge about biological lighting impacts during shift work. Furthermore it indicates lighting effects on productivity-related and subjective measures for a sleep-deprived working population.
... SD showed synergistic interactions with drugs that increase the activity of brain 5-HT,42,43,85 NA,118 and DA46 systems; conversely, DA antagonists block the behavioral119 and antidepressant120 effects of SD. Similar synergistic effects have been described for light therapy, which significantly potentiates serotonergic antidepressants,59,66 is influenced by genotypes influencing the density of the 5-HT transporter,112 and can prevent the mood-lowering effect of acute tryptophan depletion, which reduces brain 5-HT.121 ...
Chronotherapeutics refers to treatments based on the principles of circadian rhythm organization and sleep physiology, which control the exposure to environmental stimuli that act on biological rhythms, in order to achieve therapeutic effects in the treatment of psychiatric conditions. It includes manipulations of the sleep-wake cycle such as sleep deprivation and sleep phase advance, and controlled exposure to light and dark. The antidepressant effects of chronotherapeutics are evident in difficult-to-treat conditions such as bipolar depression, which has been associated with extremely low success rates of antidepressant drugs in naturalistic settings and with stable antidepressant response to chronotherapeutics in more than half of the patients. Recent advances in the study of the effects of chronotherapeutics on neurotransmitter systems, and on the biological clock machinery, allow us to pinpoint its mechanism of action and to transform it from a neglected or “orphan” treatment to a powerful clinical instrument in everyday psychiatric practice.
... Because tryptophan is a precursor to serotonin synthesis, tryptophan depletion reduces availability of serotonin in the brain, which in turn has been associated with emergence of depressive symptoms [59]. Using this established paradigm, recent work has illustrated that the mood lowering effect of tryptophan depletion in healthy women is completely blocked by carrying out the study in bright light (3,000 lux) vs. dim light (10 lux) [60]. Bright light therapy may provide a means to improve regulation of the serotonergic system in women with perinatal depression, and bright light therapy poses far less risk to the developing baby and newborn than current pharmacotherapy. ...
Perinatal depression is an important public health problem affecting 10-20% of childbearing women. Perinatal depression is associated with significant morbidity, and has enormous consequences for the well-being of the mother and child. Treatment of depression during the perinatal period poses a complex problem for both mother and clinician, as antidepressant treatment strategies must consider the welfare of both mother and child during pregnancy and lactation. Bright light therapy may be an attractive treatment for perinatal depression because it is low cost, home-based, and has a much lower side effect profile than pharmacotherapy. The antidepressant effects of bright light are well established, and there are several rationales for expecting that bright light might also be efficacious for perinatal depression. This review describes these rationales, summarizes the available evidence on the efficacy of bright light therapy for perinatal depression, and discusses future directions for investigation of bright light therapy as a treatment for perinatal depression.
... 132 Bright light exposure in mildly seasonal women prevents mood changes induced by acute tryptophan depletion; in these women, light increased serotonin levels above the threshold level below which there is a lowering of mood, indicating a direct, immediate interaction between bright light and serotonin function. 133 All this evidence supports a role for 5-HT in the direct mechanisms of the antidepressant effect of light. Other neurotransmitters postulated to play a role in depressive mood have not yet been investigated. ...
... Previous work by us and others using the same procedure has consistently shown that it leads to an approx. 70-80% decrease in plasma TRP [67,90,91] . Nonetheless, direct assessments of plasma TRP would have permitted correlations with ERPs to specific facial expressions, and should be measured in future work. ...
Depression, which is associated with dysfunctional serotonin (5-HT) activity, may be characterized by impaired emotional information processing. This study assessed the effects of acute tryptophan depletion (TRP-), which transiently lowers CNS 5-HT, on the emotion-sensitive vertex positive potential (VPP) and late positive potential (LPP) event-related potentials (ERPs) and mood in individuals with a family history of depression. The VPP and LPP are thought to index the early and later stages of motivated attentional processing, respectively.
Within a double-blind balanced design, ERPs were acquired in 18 individuals with a family history of depression (12 females) after TRP- and TRP+ (balanced) treatment while participants were presented with facial expressions (neutral, as well as sad, joy and surprise at 50 and 100% intensity) and responded to surprised faces.
TRP- increased total mood disturbance and maintained depression scores. The VPP and LPP were larger to intense versus mild expressions. Enhanced processing of emotional versus neutral faces, as indexed by the VPP, was primarily evident with TRP-. Speeded and enhanced processing of intensely joyful versus mildly sad faces was found with TRP- (VPP indexed). Compared with TRP+, TRP also increased the VPP to mildly joyful faces.
Transient 5-HT decreases in individuals with a family history of depression induce subtle changes in early stages of motivated emotional processing, though not in later ones.
... Documenting very early mood improvement with bright light exposure in SAD patients is consistent with other studies reporting that brief administration of light is clinically active. Rot et al (10) showed that bright light in contrast to dim light prevents mood lowering, induced by acute tryptophan depletion. Natural bright light in normal subjects for 30 minutes improved one dimension of mood status, 'pleasantness', on the Mood Check List 3 (11). ...
Light therapy is an effective treatment of seasonal affective disorder (SAD), when administered daily for at least several weeks. We have previously reported a small improvement in mood in SAD patients following exposure to the first hour of treatment. We now reevaluate retrospectively mood changes during shorter exposures comparing depression ratings at baseline, 20, 40, and 60 minutes of light. Participants were 15 depressed patients with SAD, untreated, who were tested during the winter season. The treatment consisted of 10,000 lux of white cool fluorescent light. Depression was measured using the 24-item NIMH scale (24-NIMH). The data were analyzed using ANOVA on ranks and Wilcoxon signed rank tests. Light resulted in significant improvement in mood at every interval when compared with baseline (p< .001). The 40 minute exposure resulted in a greater improvement than the 20 minute exposure (p < .001) but was not different from the 60 minute exposure (p < = .068). We conclude that immediate improvement in mood can be detected after the first session of light with exposures as short as 20 minutes, and that 40 minutes of exposure is not less effective than 60 minutes.
... Researchers are beginning to understand the effects of bright light from a physiological perspective, and to understand the consequences for social behaviour. Among people with showing mildly seasonal mood shifts, bright light exposure increased tryptophan uptake (aan het Rot, Benkelfat, Boivin, & Young, 2007); tryptophan is a precursor of serotonin, a neurotransmitter implicated in affective pathways. This effect might explain the observation that hospitalized patients with depression had shorter hospital stays if they had been assigned to rooms receiving more sunshine than to rooms with no direct sunlight (Beauchemin & Hays, 1996). ...
People spend much of their waking time in their workplaces (approximately 33% on a weekly basis), which raises the possibility that the conditions they experience at work influence their health and well-being. The workplace design literature has given scant attention to mental health outcomes, instead focusing on healthy populations. Conversely, the mental health literature gives scant attention to the potential contribution of workplace design in preventing mental health problems; nor does it provide much insight into facilitating return to work. Taken together, however, the literature does suggest both lines of research and possible interventions. Existing knowledge proposes that workplace design can influence mental health via the effects of light exposure on circadian regulation, social behaviour and affect; the effects of aesthetic judgement on at-work mood and physical well-being and at-home sleep quality; access to nature and recovery from stressful experiences; and privacy regulation and stimulus control. This paper includes a short review of the literature in this area, proposals for new research directions and consideration of the implications of this information on the design choices made by business owners, designers and facility managers. Providing suitable working conditions for all employees avoids stigmatizing employees who have mental health problems, while facilitating prevention and return to work among those who do.
... Ainsi, la diminution des heures d'ensoleillement à l'automne pourrait réduire le débit de sérotonine et déclencher le TAS chez certains individus vulnérables (possédant un système sérotoninergique déficient). De fait, la luminothérapie appliquée à des femmes atteintes d'une forme modérée de TAS prévient l'apparition des symptômes dépressifs déclenchés par une déplétion de tryptophane, et donc de sérotonine [25]. Une autre étude effectuée chez des participants sains confirme indirectement ce lien en montrant que le potentiel de liaison de la sérotonine à ses transporteurs augmente en automne et en hiver comparativement au printemps et à l'été. ...
Although becoming more and more recognized among physicians and psychiatrists the etiology of seasonal affective disorder (SAD) remains unclear. Indeed, the only incontestable fact is the close link between the decrease in sunlight occurring during fall and winter and the onset of depressive symptoms. But why does this seasonal decrease in the amount of light trigger a depression in some individuals while not affecting others? Why and how has sun exposure such an impact on brain-mood regulation? This review intends to shed some light on the main neurochemical hypotheses that have been advanced for the past 25 years. While several hypotheses have been advanced to explain SAD, the present review will focus on three major suspects which are: (1) melatonin due to its crucial role in circadian rhythms (2) serotonin which has been linked with depressive disorders in general and atypical symptoms and (3) catecholamine because as for serotonin, many data reported an implication of these neurotransmitter family in depressive disorders. However, similarly to other reviews about SAD, we conclude that none of those could explain the pathophysiology of this northern disease on its own.
... Other promising treatments include the stimulant modafinil [12] and the melatonin analog agomelatine [13]. Research on light therapy, the most popular treatment for SAD, has yielded generally positive results, with up to 53% of patients responding to light therapy [1,[14][15][16][17][18][19][20]. Effect sizes have been suggested to be comparable between antidepressants and light therapy [21]. ...
We investigated a carbohydrate-rich nutrient-drink mix for treatment of seasonal affective disorder (SAD). This mixture may contribute to brain serotonin synthesis, potentially exerting an antidepressant effect and controlling carbohydrate cravings. Two successive double-blind placebo-controlled studies were performed. In Study 1, 18 subjects (50% women; mean age 43 +/- 15 years) with SCID-diagnosed SAD were randomized to 12 days of twice daily carbohydrate beverage (CHO) containing mixed starches, or a placebo beverage (PRO) containing the CHO mix plus casein protein to dampen serotonin synthesis. Following a 2-day washout, subjects were crossed over to the other treatment for 12 days. In Study 2, 32 subjects (63% women; mean age 46 +/- 14 years) with SCID-diagnosed SAD were randomized to 21 days of CHO or PRO. Efficacy in both studies was determined by the first 17 items of the Hamilton Depression Rating Scale (HAM-D-28), an appetite questionnaire, and regular weighing. In Study 1, response rates were 50% for both groups. Remission rates favored CHO (50% vs. 38%), as did the decrease in the HAM-D-17 score, but differences were nonsignificant. In Study 2, response rates were 71% for CHO and 76% for PRO, and remission rates were 71% for each group. Both treatment groups experienced significant improvement in HAM-D-17 scores within 1 week of treatment, which continued through the entire study period. Weight change did not differ significantly between treatment groups in either study. The drink mix was well tolerated and treatment adherence was high. Both the active and placebo intervention were effective in alleviating symptoms of SAD. Replication studies in larger samples appear warranted.
... Tryptophan depletion has been used extensively with a single 102 g amino acid mixture devoid of tryptophan (2). With a single dose, testing after 5–7 hours, and the administration of a 1 g tryptophan tablet after testing [e.g., (3)], plasma amino acids are markedly altered only for about 5 hours, as it takes some time after the administration of the amino acid mixture for plasma tryptophan to decline. The percentage of the 168 hours in a week that plasma amino acid levels are markedly disturbed when the amino acid mixture is given daily is unknown, as tryptophan levels will tend to rise slowly after reaching their lowest level at 5–7 hours after amino acid mixture ingestion. ...
This research empirically investigates whether consumer confidence is affected by seasonal daylight fluctuations. Cross‐country panel regressions are run with two different datasets. It is found that both solar elevation and sunlight duration positively affect consumer confidence. The presence of country and year‐by‐month fixed effects as well as controls for the business cycle help rule out alternative explanations. A one standard deviation increase in solar elevation or sunlight duration is associated with a 0.03–0.04 SD increase in consumer confidence.
Introduction:
Despite the growing number of different therapeutic options, treatment of depression is still a challenge. A broader perspective reveals the benefits of bright light therapy (BLT). It stimulates intrinsically photosensitive retinal ganglion cells, which induces a complex cascade of events, including alterations in melatonergic, neurotrophic, GABAergic, glutamatergic, noradrenergic, serotonergic systems, and HPA axis, suggesting that BLT effects expand beyond the circadian pacemaker.
Areas covered:
In this review, the authors present and discuss recent data of BLT in major depressive disorder, non-seasonal depression, bipolar depression or depressive phase of bipolar disorder, and seasonal affective disorder, as well as in treatment-resistant depression (TRD). The authors further highlight BLT effects in various depressive disorders compared to placebo and report data from several studies suggesting a response to BLT in TRD. Also, the authors report data showing that BLT can be used both as a monotherapy or in combination with other pharmacological treatments.
Expert opinion:
BLT is an easy-to-use and low-budget therapy with good tolerability. Future studies should focus on clinical and biological predictors of response to BLT, on defining specific populations which may benefit from BLT and establishing treatment protocols regarding timing, frequency, and duration of BLT.
Thema dieses Kapitels ist unsere evolutionäre „Bestimmung“: Die Programme, die in uns liegen und Anteil haben an unseren Bedürfnissen, werden beleuchtet und unserem tatsächlichen „Tun“ gegenübergestellt. Eine kritische Auseinandersetzung mit dem ungebremsten Sitzkonsum geht einem Plädoyer für das Training der „freundlichen Ausdauer“ und der sozialen Eingebundenheit „Gemeinsam ist besser als einsam“ voraus. Praktische Tipps für die Umsetzung schließen das Kapitel ab.
Typical home lighting practice is mainly centred on visual aspects to enable safe movement between spaces, flexibility in multiuse spaces, a sense of aesthetics and energy efficiency. Whilst lighting impacts on the health of residents have not received similar consideration, this area is gaining increasing interest. This is even more important and actual in the context of the recent pandemic where people have been working or studying from home. A combination of bright daytime light and night-time darkness is essential for circadian entrainment and maintenance of a regular daily sleep–wake cycle, whereas exposure to light at night can negatively impact circadian rhythms and sleep patterns and ultimately lead to potential health problems. Additionally, lighting also has the potential to affect health through associated effects such as flicker, glare, optical hazards or electromagnetic fields. This article discusses the main areas of concern related to home lighting and outlines general recommendations to limit detrimental effects and contribute to good health.
Light can impact human health via the visual and non-visual systems originating in the retina of the eye or as optical radiation falling on eye or skin. This paper provides a summary of what is known about these impacts. Topics covered include aspects of lighting likely to cause eyestrain and headaches; increase the risk of falls; induce circadian disruption; enhance sleep; mitigate Alzheimer’s disease and depression; produce tissue damage; alleviate diseases through phototherapy and inactivate viruses through germicidal irradiation. It is concluded that human health is undoubtedly influenced by lighting, but there are four conditions that should be attached to such a simple assertion. First, the impact of lighting on human health can be either positive or negative. Second, human health is affected by many factors other than lighting. Third, the severity of the effects of light exposure can vary widely from the short-lived and trivial to the long-term and fatal. Fourth, the same lighting conditions can have very different health impacts for different individuals depending on their age and medical status. Taken together, these conditions imply that care is required when judging the veracity and relevance of broad assertions about the benefits of lighting for human health.
When designing schools, universities, or any educational centers, daylight in classrooms is usually one of the essential issues that take the architect's attention. Its importance comes from the fact that daylight can impact students' health, mood, and visual performance. Providing an appropriate amount of uniformly distributed light with glare protection is a significant factor in classroom design (Zomorodian Z S, 2016). This study is based on a literature review, studies, and articles researching the effect of daylight in a classroom environment on students' performance. It tends to define the significance of daylight design in the learning environment. This paper also deals with specifying and exploring all the conditions, factors, and elements that contribute to creating this successful daylight design in classrooms. Besides, it investigates the daylight design of the buildings at the campus of Sarajevo that will, later on, contribute to the creation of a design manual of all the considerations that need to be taken for schools and educational centers’ daylight design. The study is conducted at the campus of Sarajevo in the academic year 2019. The literature review, data study, and previous studies define the significance of daylight in the classroom environment and show the correlation between daylight and students' achievement in the classroom environment. It defines the elements and conditions of successful daylight design in classroom settings. The study explored the current state of the daylight design at the campus of Sarajevo detecting its lacks and obstacles regarding adequate illumination. Based on the literature review, an appropriate solution for the investigated classroom environment has been designed.
Since the discovery of the intrinsically photosensitive retinal ganglion cells (ipRGCs), an
increasing number of studies on Non-image forming effects (NIF) of light revealed evidence for acute changes in the level of alertness, mood and cognitive performance during the biological night and day. Regarding the influence of ambient light on cognitive performance in healthy day-active people, however, studies have revealed even more equivocal findings. Light’s effect on cognition is moderated by many factors, chief among them are the parameters of light (intensity and spectrum), lighting pattern, timing (time of day and year), personality characteristics and the nature of the task. For future research should pay more attention to investigating the relationship between light level and performance with multiple manipulations of light, exploring dynamic lighting system, developing customized personalized luminaire and testing molecular biological mechanism of NIF effect of light.
Manipulation of lighting regimens is an effective way to improve the broiler production. The growing health and welfare concern for the livestock animals has raised new requirements for lighting management. In the present study, the overall responses including growth, carcass composition characteristics, health and welfare, and behavior of broilers to 3 lighting regimens (near-continuous lighting (23 h light (L):1 h darkness (D)), constant 16-h lighting (16L:8D), and constant 16-h lighting with a 2-h night interruption (16L:2D:2L:4D) were estimated, aiming at providing an optimal regimen required for both good welfare and production. A total of 360 day-old male broiler chicks (Cobb 500) obtained from a commercial hatchery were used. The chicks were randomly divided into 3 treatments, which were replicated for 4 times. The 3 lighting regimens aforementioned were initiated on d 8 and ended on d 42. For the whole study period (d 0–42), the feed conversion ratios of broilers under 16L:8D and 16L:2D:2L:4D did not differ, while the broiler chickens under 16L:2D:2L:4D had higher feed intake and BW gain (P < 0.05). The broiler chickens under 16L:2D:2L:4D had similar feed intake as those under 23L:1D, while the BW gain was higher (P < 0.05) and the feed conversion ratio was lower (P < 0.05). Slaughtered on d 42, the breast muscle yield of broiler chickens under 16L:2D:2L:4D was similar to those under 23L:1D, but higher than those under 16L:8D (P < 0.05). The abdominal fat weight of broiler chickens under 16L:2D:2L:4D was similar to those under 23L:1D, but lower than those under 16L:8D (P < 0.05). The eyeball weight and size of broilers under 16L:2D:2L:4D were smaller than those under 23L:1D (P < 0.05). As a contributor of feeling of well-being, the serum serotonin level did not differ for the broiler chickens from the 3 lighting regimens. The serum melatonin of broilers under the 16L:8D was higher than other 2 regimens (P < 0.05). Behavior observation on d 30 indicated that the broiler chickens under the 23L:1D regimen spent more time feeding than those under 16L:8D, but exhibited comfort behaviors less extensively than other 2 regimens (P < 0.05). It was concluded from this study that the 16L:2D:2L:4D regimen improved the growth, feed efficiency, carcass composition characteristics, ocular and leg health and welfare of male Cobb broilers due to the dark period and a 2-h night interruption.
The scientist-practitioner training model in doctoral clinical and counseling psychology programs encourages reliance on data, rather than personal opinion, to inform decision-making processes. This study provided unique experimental evidence that this standard is being met. Doctoral students in clinical and counseling psychology (N = 162) reviewed a brief manuscript, presumably submitted for publication, that described a new suicide assessment measurement procedure. Respondents were randomly forwarded one of five manuscript versions that varied only in the theoretical rationale used to justify the proposed assessment procedure. Theoretical incongruence between respondents and "authors" were expected to lower ratings of manuscript quality and data merits. Only modest rating variation was ultimately attributed to theoretical incongruence. Students from varied backgrounds and programs instead focus attention on the data, rather than the theoretical underpinnings, presented in their assigned manuscript. This evidence of objectivity in student manuscript analysis generalized across gender, training specialty, level of scholarly productivity, and career aspiration.
This book chapter is available upon request (alan.king@und.edu).
A misalignment between circadian rhythms and the sleep–wake schedule can result in decreases in sleep quality, with negative impacts on various mental and physical conditions. Because light is the most powerful synchronizer of human circadian rhythms, appropriately timed bright light exposure can be used as a means of fostering adaptive phase shifts, and also as a nonpharmacological therapeutic option for alleviating depressive mood symptoms. Applications of light therapy in the treatment of shift work sleep disorder, advanced and delayed sleep phase disorder, and mood disorders including seasonal affective disorder, major depressive disorder, premenstrual dysphoric disorder, and bipolar disorder are discussed.
There is a growing body of evidence suggesting that nonpharmacological interventions have an appropriate place in the treatment of major depressive disorders (MDDs) as both stand-alone and supplemental treatments. Because women may be reluctant to use psychotropic medications due to strong values or treatment preferences during specific reproductive events, clinicians need to be able to offer empirically based alternatives to medication. In this review, we present recent findings from studies of acupuncture, bright light therapy, electroconvulsive therapy, omega fatty acid supplementation, physical activity, and psychosocial intervention for women experiencing depressive symptoms in the contexts of menstruation, pregnancy, postpartum, and menopause.
Seasonal affective disorder (SAD) is a polyfactorial and polygenetic disorder that involve biological and psychological sub-mechanisms that differentially involve depression, seasonality, circadian rhythms, retinal sensitivity, iris pigmentation, sleep factors, and the neurotransmitters involved with these systems. Within the framework of the polyfactorial conceptualization of SAD, we review the possible contributions of vitamin D3 with respect to the aforementioned sub-mechanisms. We hypothesize that rather than functioning primarily as a proximal or direct sub-mechanism in the etiology of SAD, vitamin D likely functions in a more foundational and regulative role in potentiating the sub-mechanisms associated with the depressive and seasonality factors. There are several reasons for this position: 1. vitamin D levels fluctuate in the body seasonally, with a lag, in direct relation to seasonally-available sunlight; 2. lower vitamin D levels have been observed in depressed patients (as well as in patients with other psychiatric disorders) compared to controls; 3. vitamin D levels in the central nervous system affect the production of both serotonin and dopamine; and 4. vitamin D and vitamin D responsive elements are found throughout the midbrain regions and are especially concentrated in the hypothalamus, a region that encompasses the circadian timing systems and much of its neural circuitry. We also consider the variable of skin pigmentation as this may affect levels of vitamin D in the body. We hypothesize that people with darker skin pigmentation may experience greater risks for lower vitamin D levels that, especially following their migration to regions of higher latitude, could contribute to the emergence of SAD and other psychiatric and physical health problems.
Despite evidence that bright light can improve mood, the neurobiology remains poorly understood. Some evidence implicates the catecholamines. In the present study, we measured the effects of transiently decreasing dopamine (DA) synthesis on mood and motivational states in healthy women with mild seasonal mood changes who were tested in either bright or dim light.
On 2 test days, participants slept overnight in a light-controlled room. On the morning of each session, half of the participants awoke to gradual increases of bright light, up to 3000 lux, and half to dim light (10 lux). For all participants, DA was reduced on 1 of the test days using the acute phenylalanine/tyrosine depletion (APTD) method; on the other day, they ingested a nutritionally balanced control mixture (BAL). Beginning 4 hours postingestion, participants completed subjective mood questionnaires, psychological tests and a progressive ratio breakpoint task during which they worked for successive units of $5.
Thirty-two women participated in our study. The APTD lowered mood, agreeableness, energy and the willingness to work for monetary reward. The effects on energy and motivation were independent of light, while the effects on mood and agreeableness were seen in the dim condition only, being prevented by bright light.
Acute phenylalanine/tyrosine depletion might affect systems other than DA. The sample size was small.
These results suggest that increased DA function may be responsible for some of the beneficial effects of light, while adding to the evidence that the neurobiology of mood and motivational states can be dissociated.
Introduction:
Tryptophan depletion (TD) is an established method to influence the serotonergic system and mood. The purpose of this study was to examine the effect of TD under different ambient light conditions, measured through serotonin-associated plasma levels and a visual analog scale (VAS), on healthy females.
Methods:
Thirty-eight healthy female s-allele carriers of the serotonin transporter promoter gene (5-HTTLPR) were administered a TD under dim light conditions (75 lx). A sub-group of 8 participants repeated the procedure randomized in two additional light conditions (585 lx and 1530 lx respectively). Prior to, and 5h following administration of TD, various variables (serotonin-associated plasma levels, VAS) were measured. Due to not normal distributed data, non-parametric statistical tests were used.
Results:
Overall analysis showed a significant mood lowering effect of TD. Moreover, TD decreased all measured serotonin-associated plasma levels significantly. Significant differences in varying light conditions were found for the VAS and plasma tryptophan, with the greatest effect of TD in the 75 lx condition.
Conclusion:
Results of our study showed an influence of even slight differences in ambient light intensity on the effect of TD concerning mood as well as on the serotonergic system.
The acute tryptophan depletion (ATD) technique has been used extensively to study the effect of low serotonin in the human brain. This review assesses the validity of a number of published criticisms of the technique and a number of previously unpublished potential criticisms. The conclusion is that ATD can provide useful information when results are assessed in conjunction with results obtained using other techniques. The best-established conclusion is that low serotonin function after tryptophan depletion lowers mood in some people. However, this does not mean that other variables, altered after tryptophan depletion, are necessarily related to low serotonin. Each aspect of brain function has to be assessed separately. Furthermore, a negative tryptophan depletion study does not mean that low serotonin cannot influence the variable studied. This review suggests gaps in knowledge that need to be filled and guidelines for carrying out ATD studies.
In a recent editorial, Pierre Blier discussed some of the reasons that new antidepressants have become a rarity.1 The situation is serious enough that GlaxoSmithKline and Astra-Zeneca have decreased work in many areas of psychiatry, and a recent article in Science asks, “Is pharma running out of brainy ideas?”.2 One of the problems is a lack of any clear understanding of the etiology of depression. As Krishnan and Nestler3 have pointed out, “Unlike Parkinson’s or Alzheimer’s disease, depression lacks any clear consensus neuropathology, rare familial genetic causes, or highly penetrant vulnerability genes, providing no obvious starting points for molecular investigations.” The important progress in understanding the etiology of Alzheimer disease has resulted recently in more than a dozen trials of experimental treatments, none of which has shown any therapeutic effect.4 So, what hope is there for progress in treating depression?
An essential component of the human diet, L-tryptophan is critical in a number of metabolic functions and has been widely used in numerous research and clinical trials. This review provides a brief overview of the role of L-tryptophan in protein synthesis and a number of other metabolic functions. With emphasis on L-tryptophan's role in synthesis of brain serotonin, details are provided on the research uses of L-tryptophan, particularly L-tryptophan depletion, and on clinical trials that have been conducted using L-tryptophan supplementation. The ability to change the rates of serotonin synthesis in the brain by manipulating concentrations of serum tryptophan is the foundation of much research. As the sole precursor of serotonin, experimental research has shown that L-tryptophan's role in brain serotonin synthesis is an important factor involved in mood, behavior, and cognition. Furthermore, clinical trials have provided some initial evidence of L-tryptophan's efficacy for treatment of psychiatric disorders, particularly when used in combination with other therapeutic agents.
It is common in studies of interpersonal characteristics to examine personality variables as static predictors. Yet in recent years it has also become possible to examine personality and related interpersonal processes as they unfold over time in association with event specific cues. The present article reviews research that (1) identifies behaviors that reflect the occurrence of hostile-irritable-quarrelsome traits in daily life, (2) demonstrates both the stability and within-person variability of these behaviors over time, (3) documents event-level interpersonal cues that are systematically associated with within-person variation in quarrelsome behavior, and (4) describes how dispositional level agreeableness and irritability moderate the associations of event-level cues with quarrelsome behavior. The influence of the neurotransmitter serotonin on quarrelsome behavior is also considered. The studies indicate that quarrelsome individuals have reduced affective reactivity to engaging in quarrelsome behavior, increased behavioral reactivity to perceptions of quarrelsomeness in others, and greater responsiveness to change in serotonin levels.
This study assessed the effects of acute tryptophan depletion (ATD), which transiently lowers CNS 5-HT, on electrocortical responses to facial expression processing in individuals with a family history of depression (FH+). Electroencephalograph (EEG)-derived event-related potentials (ERPs) were acquired from 18 FH+ individuals during a facial expression recognition task (neutral and sad, joy and surprise at 50% and 100% intensities). Both early positive (P1 and P2) and the face-specific N170 ERP components were differentially altered by emotional intensity and valence. Increased depression, confusion and total mood disturbance scores, and decreased calmness, were observed with ATD (versus placebo). ATD was also associated with enhanced P1 and P2 amplitudes for sad versus joyful expressions. The N170 was not modulated by treatment, but was affected by emotive valence. Therefore, ATD enhanced ERP-indexed early processing of sad facial expressions, and altered the processing of positive ones, in FH+ individuals.
Objective:
To determine if the antidepressant effect of 1 hour of light therapy is predictive of the response after 1 and 2 weeks of treatment in patients with seasonal affective disorder (SAD).
Patients:
Twelve patients with SAD.
Setting:
National Institutes of Health Clinical Center, Bethesda, Md.
Interventions:
Light therapy for 2 weeks.
Outcome measures:
Scores on the Seasonal Affective Disorder Version of the Hamilton Depression Rating Scale (SIGH-SAD) on 4 occasions (before and after 1 hour of light therapy and after 1 and 2 weeks of therapy) in the winter when the patients were depressed. Change on typical and atypical depressive scores at these time points were compared.
Results:
Improvement of atypical depressive symptoms after 1 hour of light therapy positively correlated with improvement after 2 weeks of therapy.
Conclusion:
In patients with SAD, the early response to light therapy may predict some aspects of long-term response to light therapy, but these results should be treated with caution until replicated.
In a previous study we found that a tryptophan-deficient amino acid mixture, designed to lower tissue tryptophan and thus brain 5-hydroxytryptamine (5HT) levels, caused a rapid (5 h) lowering of mood in normal males. Because of the importance of this evidence indicating a direct causal connection between low 5HT and low mood, we have now investigated other possible explanations for the mood lowering effect. Research strongly supports the involvement of environmental setting and cognition in the production and experience of emotions. Therefore we investigated how these factors might influence the mood-lowering effects of tryptophan depletion. In an instructional manipulation subjects were either supplied or not supplied with information designed to account for any possible peripheral sensations that might be related to depressive affect. In an environmental manipulation subjects were exposed either to a supportive and comfortable atmosphere (positive environment), or an unrewarding and unstimulating environment (negative environment). In the control group, which received a balanced amino acid mixture, the positive and negative environments had the expected effects on the scores of the Multiple Affect Adjective Checklist, thus indicating the effectiveness of these procedures. In the tryptophan depletion group neither the instructional nor the environmental manipulation had any influence on the mood lowering effect. It may be that tryptophan depletion lowers mood in normal males because low 5HT influences mood directly rather than via cognitive processes. Our data strongly support the idea that 5HT exerts an effect on mood and that low 5HT may, in some patients, be an important factor contributing to the etiology of clinical depression.
The authors treated winter depression in 13 patients with typical seasonal affective disorder by extending the length of winter days with bright and dim light in the morning and evening in a balanced-order crossover study. Bright light had a marked antidepressant effect, whereas the dim light did not. This response could not be attributed to sleep deprivation. Subsequent pilot studies indicated that bright evening light alone is probably also effective. Several patients were able to maintain the antidepressant response throughout the winter months by continuing daily light treatments.
Normal male human subjects ingested amino acid mixtures which were tryptophan-free, balanced or contained excess tryptophan. The tryptophan-free mixture causes a marked depletion of plasma tryptophan by 5 h. At this time the subjects in the tryptophan-free group had significantly elevated scores on the depression scale of the Multiple Affect Adjective Checklist. The tryptophan-free group also performed worse than the other two groups in a proofreading task carried out while listening to a tape with themes of hopelessness and helplessness (dysphoric distractor). Cognitive theories of depression predict greater distractability of depressed individuals by dysphoric themes. Thus, both measures indicate a rapid mood lowering effect of tryptophan depletion in normal males. This effect is probably mediated by a lowering of brain 5-hydroxytryptamine. Although the mood-lowering effect was not as great as that seen in depressed patients, our results suggest that low brain 5HT might be one factor precipitating depression in some patients.
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.
Bright artificial light suppressed nocturnal secretion of melatonin in six normal human subjects. Room light of less intensity,
which is sufficient to suppress melatonin secretion in other mammals, failed to do so in humans. In contrast to the results
of previous experiments in which ordinary room light was used, these findings establish that the human response to light is
qualitatively similar to that of other mammals.
Enhanced endogenous serotonergic activity, stimulated by L-tryptophan (TRYPT) loading, was found to have a substantial impact on neurochemical and behavioral aspects of the circadian response to light in the male Syrian hamster. An intraperitoneal (i.p.) injection of 150 mg/kg TRYPT significantly stimulated serotonin (5-HT) release in the suprachiasmatic nuclear (SCN) region, as reflected by a 205 ± 30% maximal increase in the extracellular concentration of 5-HT assessed using microdialysis. Administration of TRYPT 1 h before exposure to a light pulse (30 min, 40 lux) delivered during late subjective night dose-dependently suppressed the number of SCN cells expressing light-induced Fos-like immunoreactivity (Fos-LI; maximal suppression @200 mg/kg was 77 ± 4%, p < 0.001). This action of TRYPT was attenuated by pretreatment with the 5-HT1a antagonist, NAN-190, and was abolished by the 5-HT2/5-HT7 antagonist, ritanserin, or the nonselective 5-HT antagonist, metergoline (all 10 mg/kg). These antagonists alone had no effect on light-induced Fos. In a second experiment, pretreatment of free-running hamsters housed under constant darkness with 150 mg/kg TRYPT 45-60 min prior to light exposure (10 min, 20 lux) during late subjective night (CT 19) significantly attenuated the light-induced phase advances of the circadian activity rhythm (66 ± 7 min vs. 100 ± 6 min for vehicle controls; p < 0.001). The same dose of TRYPT given 1 h before lights-on for 5 consecutive days in hamsters maintained under 14L:10D altered the phase angle of entrainment such that activity onsets were delayed by 36 ± 8 min relative to controls (p < 0.05). The same dose of TRYPT administered during late subjective night also suppressed the extracellular concentration of glutamate in the SCN region assessed using microdialysis (55 ± 8% suppression; p < 0.05 vs. baseline). These results support the hypothesis that the ascending serotonergic projection to the SCN modulates photic entrainment processes within the circadian oscillator.
A double-blind placebo-controlled cross-over study in which plasma tryptophan was manipulated by administration of a tryptophan-deficient amino acid mixture. In the placebo condition, all subjects received a nutritionally balanced amino acid mixture that contained tryptophan. To further standardize baseline amino acids, each subject was provided with a low-protein diet the day before amino acid challenges. Subjects were euthymic, healthy men aged 18 to 30 years with either a multigenerational family history of affective illness or no family history of psychiatric illness in the present or in the two previous generations. Each subject was screened with a structured clinical interview to rule out a personal history of psychiatric illness.
Plasma tryptophan was reduced by 89% 5 hours after the administration of the tryptophan-deficient amino acid mixture. Six of 20 subjects with a family history of affective illness and none of 19 subjects without a family history of psychiatric illness showed a lowering of mood of 10 or more points on the Profile of Mood States depression scale (P = .012, Fisher's Exact Test) 5 hours after tryptophan depletion. No significant mood changes were observed following the control treatment (balanced amino acid mixture) in either group.
Our data support the hypothesis that subjects with no prior depressive episodes but with a multigenerational family history of major affective disorder show a greater reduction in mood after tryptophan depletion. They are also consistent with theories that implicate deficient serotonergic function as one possible etiological factor in major depressive disorders.
Previous studies show that rapid tryptophan depletion reverses the effects of therapy with serotonergic, but not noradrenergic, antidepressant drugs in patients with remitted nonseasonal depression. The objective of this study was to investigate the effects of rapid tryptophan depletion in patients with seasonal affective disorder (SAD) that was in clinical remission after light therapy.
Patients who met DSM-III-R criteria for recurrent major depressive episodes, seasonal (winter) pattern (equivalent to SAD), were treated with a standard course of light therapy. Ten patients with SAD in clinical remission after light therapy underwent rapid tryptophan depletion in a placebo-controlled, double-blind crossover study. Behavioral ratings and plasma tryptophan levels were obtained before and after rapid tryptophan depletion.
Plasma total and free tryptophan levels were significantly reduced to 20% of normal levels by the rapid tryptophan depletion. The depletion session resulted in significant increases in depression scores compared with the sham control session. Six of 10 patients had a clinically significant relapse of their depression following the tryptophan depletion session.
Rapid tryptophan depletion appears to reverse the antidepressant effect of bright light therapy in patients with SAD. This suggests that the therapeutic effects of bright light in SAD may involve a serotonergic mechanism.
Patients with seasonal affective disorder (SAD) were treated for 1 week either with a daily 1-h morning walk outdoors (natural light) or low-dose artificial light (0.5 h@2800 lux). The latter treatment (given under double-blind conditions) can be considered mainly placebo and did not improve any of the depression self-ratings, whereas natural light exposure improved all self-ratings. According to the Hamilton depression score, 25% remitted after low-dose artificial light and 50% after the walk. Sleep duration or timing were not crucial for the therapeutic response. The morning walk phase-advanced the onset and/or offset of salivary melatonin secretion, but individual clinical improvement could not be correlated with specific phase-shifts. Morning cortisol was decreased. Low-dose artificial light did not modify melatonin or cortisol patterns. This is the first study to provide evidence for the use of outdoor light exposure as a potential alternative or adjuvant to conventional artificial light therapy in SAD.
Several studies of healthy volunteers have revealed that subjective mood may vary with the duration of prior wakefulness and with the time of day. However, in these studies, the effects of extended wakefulness and circadian phase remained confounded, and the interaction of these 2 processes could not be assessed quantitatively.
In the present study, a total of 24 healthy young subjects (16 men, 8 women) lived on a 30-hour sleep-wake schedule for 19 to 23 days or on a 28-hour sleep-wake schedule for 33 to 36 days; both schedules induced desynchrony between the subjects' sleep-wake cycle and their endogenous circadian pacemaker. Subjective mood was assessed by 2 types of visual analog scales, which were administered twice every 2 hours and every 20 minutes, respectively, during all scheduled wakefulness episodes. A circadian phase and an interval elapsed since awakening were attributed to each data point, and circadian and wake-dependent fluctuations of mood were assessed.
A significant variation of mood with circadian phase was observed, but no reliable main effect of the duration of prior wakefulness was found. A statistically significant interaction of circadian and wake-dependent fluctuations was evident; when the analysis was restricted to specific circadian phases, mood improved, deteriorated, or remained stable with the duration of prior wakefulness.
These results indicate that, in healthy young subjects, subjective mood is influenced by a complex and nonadditive interaction of circadian phase and duration of prior wakefulness. The nature of this interaction is such that moderate changes in the timing of the sleep-wake cycle may have profound effects on subsequent mood.
Rates of serotonin synthesis were measured in the human brain using positron emission tomography. The sensitivity of the method is indicated by the fact that measurements are possible even after a substantial lowering of synthesis induced by acute tryptophan depletion. Unlike serotonin levels in human brain, which vary greatly in different brain areas, rates of synthesis of the indolamine are rather uniform throughout the brain. The mean rate of synthesis in normal males was found to be 52% higher than in normal females; this marked difference may be a factor relevant to the lower incidence of major unipolar depression in males.
Longitudinal data, or data that are repeated measurements on various subjects across time, are commonplace in biostatistical studies. The general linear mixed model is a useful statistical tool for analyzing such data and drawing meaningful inferences about them. This paper discusses some of the most common mixed models and fits them to a prototypical example involving repeated measures on blood pressure. Computer implementation is via the MIXED procedure in the SAS System, and code descriptions and output interpretations accompany the example.
Objective
To review the status of current treatment of seasonal affective disorder (SAD).
Method
Treatment studies of SAD published between January 1989 and March 1995 were identified using a computerized MEDLINE literature search. Additional citations were obtained from the reference sections of these articles. Studies included in this review were selected using operational methodologic criteria.
Results
Many studies support the efficacy of bright light therapy using a fluorescent light box. The best studied protocol is >2500 lux white light for 2 hours per day, but newer protocols using 10,000 lux for 30 minutes have comparable response rates. Studies of light visors and other head-mounted devices also report similar response rates, but have not yet shown superiority over putative control conditions. There are fewer medication studies in SAD, but controlled studies suggest that fluoxetine, d-fenfluramine and propranolol are effective. Other treatments such as dawn simulation require further study. No studies of psychological treatments for SAD were found. Many studies had methodologic limitations, including brief treatment periods, small sample sizes, and lack of replication, that limit the generalizability of findings.
Conclusion
There are several well-studied, effective treatments for SAD, including light therapy and medications. However, further research must be done to demonstrate sustained treatment response over time, to clarify the intensity-response relationship of light therapy, to clarify the role of light therapy and medications, and to assess combination treatments.
• Data concerning familial history of psychiatric disorders are often used to assist in diagnosis, to examine the role of genetic or nongenetic familial factors in etiology, or to develop new methods of classification. Information concerning familial prevalence may be collected by two different methods: the family history method (obtaining information from the patient or a relative concerning all family members), and the family study method (interviewing directly as many relatives as possible concerning their own present or past symptomatology). This study compares these two methods. In general, the family study method is preferred since information is likely to be more accurate. The family history method leads to significant underreporting, but this can be minimized through the use of diagnostic criteria. This study reports on an instrument that has been developed for collecting information concerning family history and that provides criteria for 12 diagnoses—the Family History-Research Diagnostic Criteria. Using diagnostic criteria leads to greater sensitivity, but underreporting remains a major problem of the family history method.
• 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.
Background:
A dysfunction of the serotonin system may play a major role in the pathogenesis of seasonal affective disorder. Bright light therapy has been shown to be effective in the treatment of winter depression in patients with seasonal affective disorder. Light therapy—induced remission from depression may be associated with changes in brain serotonin function.
Methods:
After at least 2 weeks of clinical remission, 12 drug-free patients who had had depression with seasonal affective disorder underwent tryptophan depletion in a double-blind, placebo-controlled, balanced crossover design study.
Results:
Short-term tryptophan depletion induced a significant decrease in plasma free and total tryptophan levels (P<.001 for both, repeated measures analysis of variance), with peak effects occurring 5 hours after ingestion of a tryptophan-free amino acid drink. It emerged that tryptophan depletion leads to a transient depressive relapse, which was most pronounced on the day after the tryptophan-depletion testing. No clinically relevant mood changes were observed in the control testing.
Conclusions:
The maintenance of light therapy—induced remission from depression in patients with seasonal mood cycles seems to depend on the functional integrity of the brain serotonin system. Our results suggest that the serotonin system might be involved in the mechanism of action of light therapy.
• Brain serotonin content is dependent on plasma levels of the essential amino acid tryptophan. We investigated the behavioral effects of rapid tryptophan depletion in patients in antidepressant-induced remission. Twenty-one patients who were depressed by DSM-III-R criteria received a 24-hour, 160-mg/d, lowtryptophan diet followed the next morning by a 16—amino acid drink, in a double-blind, placebo-controlled (acute tryptophan depletion and control testing), crossover fashion. Total and free tryptophan levels decreased 87% and 91%, respectively, during acute tryptophan depletion. Fourteen of the 21 remitted depressed patients receiving antidepressants experienced a depressive relapse after the tryptophan-free amino acid drink, with gradual (24 to 48 hours) return to the remitted state on return to regular food intake. Control testing produced no significant behavioral effects. Free plasma tryptophan level was negatively correlated with depression score during acute tryptophan depletion. The therapeutic effects of some antidepressant drugs may be dependent on serotonin availability.
TEMPORAL changes of serotonin (5-HT) content in the median (MRN) and dorsal (DRN) raphe nuclei were measured in rats kept under various lighting conditions. Serotonin content in the MRN and DRN under light-dark (LD) condition showed diurnal rhythmicity, with a peak during early light wphase and a trough during the dark phase. In constant dark (DD) condition, a single peak was observed and was out of phase to the 5-HT peak found under LD condition. Animals exposed to constant light (LL) after 2 days in DD showed marked increase in 5-HT after lights on. These results suggest that changes in 5-HT in the MRN and DRN are regulated by an endogenous pacemaker and by light.
(C) Lippincott-Raven Publishers.
A quantitative computer analysis was made of the spontaneous activity of 46 midbrain raphe units in the anesthetized rat. These units are characterized by a slow and rhythmic discharge rate which remains stable over time. Cells in the dorsal raphe, median raphe and brachium conjunctivum did not differ in this respect. A subpopulation of cells in the dorsal raphe exhibited regular, periodic oscillations in discharge rate. Response of raphe units to light flashes and light and dark conditions was also studied. Of 44 units tested, there was a tendency toward higher rates of discharge in the light. Effects of light flashes were examined in 34 units. Raphe cells were typically unresponsive to light flashes.
Patients with seasonal affective disorder (SAD) were treated for 1 week either with a daily 1-h morning walk outdoors (natural light) or low-dose artificial light (0.5 h @ 2800 lux). The latter treatment (given under double-blind conditions) can be considered mainly placebo and did not improve any of the depression self-ratings, whereas natural light exposure improved all self-ratings. According to the Hamilton depression score, 25% remitted after low-dose artificial light and 50% after the walk. Sleep duration or timing were not crucial for the therapeutic response. The morning walk phase-advanced the onset and/or offset of salivary melatonin secretion, but individual clinical improvement could not be correlated with specific phase-shifts. Morning cortisol was decreased. Low-dose artificial light did not modify melatonin or cortisol patterns. This is the first study to provide evidence for the use of outdoor light exposure as a potential alternative or adjuvant to conventional artificial light therapy in SAD.
We mailed a questionnaire to patients affected with seasonal affective disorder (SAD) to determine patterns of self-selected light use and efficacy of treatment. Data obtained from 127 patients who responded indicate that despite inconvenience and other use-limiting factors, many patients with SAD derive sustained benefit from phototherapy over months. No consistent pattern or duration of effective treatment emerged. Development of a less cumbersome means of delivering phototherapy and reimbursement by insurance companies remain concerns to patients.
Seasonal Affective Disorder (SAD) is a recently-defined variant of recurrent major depression which is understood as having a uniquely biological aetiology. Notwithstanding the appealing simplicity of light's putative role in the aetiology and treatment of SAD, there are a priori grounds for expecting that a wider range of variables might be relevant. Based on the accepted description of SAD as a continuum of mood vulnerability and the clinical overlap between SAD and neurotic depression, it was hypothesized that the trait construct of neuroticism might prove relevant to SAD. Results suggested that the tendency to report seasonal variation in SAD symptoms covaries with neuroticism. Furthermore, reports of seasonality were found to covary with a tendency to attribute moods to non-seasonal environmental factors beyond the individual's control.
Administered 16 visual analog scales to 8 normal Ss to test the validity of the scales in measuring drug effects; Ss received 150 mg of butobarbitone sodium, 15 and 30 mg of flurazepam, and a placebo. Results indicate that (a) there were no significant effects on Factor 1 (Alertness), but there was a tendency for Ss to rate themselves as more alert after placebo; (b) there was a significant Drug * Times interaction effect on Factor 2 (Contentedness); and (c) Factor 3 (Calmness) also showed a significant Drug * Times interaction effect which was caused by the anti-anxiety effect of flurazepam. (15 ref) (PsycINFO Database Record (c) 2004 APA, all rights reserved)
Deficiencies in brain serotonin function are believed to play an important role in the pathophysiology of seasonal affective disorder/winter type (SAD). However, no direct evidence has been reported so far that lowered brain serotonin activity causes the symptoms of SAD.
We studied 11 SAD patients who had suffered recurrent winter depressive episodes of SAD and were fully recovered and off treatment during the summer. In a randomized, balanced, double-blind crossover design patients received two amino acid beverages, one containing tryptophan and the other containing no tryptophan but otherwise identical. Behavioural ratings and plasma total and free tryptophan concentrations were assessed at baseline before administration of the amino acid beverages and at several time points afterwards.
The tryptophan-free amino acid beverage induced significant decreases of plasma total and free tryptophan levels and both levels increased during sham depletion (condition x time interaction: P < 0.001). Tryptophan depletion, but not sham depletion caused a transient return of depressive symptoms (condition x time interaction: P < 0.001).
The present study demonstrates that SAD patients in remission during the summer are vulnerable to a return of depression when depleted of tryptophan. This finding supports the importance of serotonergic mechanisms in the pathophysiology of SAD.
Data concerning familial history of psychiatric disorders are often used to assist in diagnosis, to examine the role of genetic or nongenetic familial factors in etiology, or to develop new methods of classification. Information concerning familial prevalence may be collected by two different methods: the family history method (obtaining information from the patinet or a relative concerning all family members), and the family study method (interviewing directly as many relatives as possible concerning their own present or past symptomatology). This study compares these two methods. In general, the family study method is preferred since information is likely to be more accurate. The family history method leads to significant underreporting, but this can be minimized through the use of diagnostic criteria. This study reports on an instrument that has been developed for collecting information concerning family history and that provides criteria for 12 diagnoses--the Family History-Research Diagnostic Criteria. Using diagnostic criteria leads to greater sensitivity, but underreporting remains a major problem of the family history method.
Patients with recurrent winter depression and its subsyndromal form have been reported to benefit from bright full-spectrum light (phototherapy). In order to determine whether this treatment (2 h in the morning) during winter is effective in a random sample of the general population we investigated the responses of 20 subjects with varying degrees of winter difficulties. A control group (n = 20) matched for the degree of seasonality, age, and sex was treated with dim light. Individuals were selected from a larger survey sample of the Montgomery County population (MD, U.S.A.) and were comparable to the latter in their degree of winter difficulties. Enhancement of environmental light does not, on the basis of the present study, appear to be indicated for the public at large, but rather for a subgroup of individuals with histories of winter difficulties.
Brain serotonin content is dependent on plasma levels of the essential amino acid tryptophan. We investigated the behavioral effects of rapid tryptophan depletion in patients in antidepressant-induced remission. Twenty-one patients who were depressed by DSM-III-R criteria received a 24-hour, 160-mg/d, low-tryptophan diet followed the next morning by a 16-amino acid drink, in a double-blind, placebo-controlled (acute tryptophan depletion and control testing), crossover fashion. Total and free tryptophan levels decreased 87% and 91%, respectively, during acute tryptophan depletion. Fourteen of the 21 remitted depressed patients receiving antidepressants experienced a depressive relapse after the tryptophan-free amino acid drink, with gradual (24 to 48 hours) return to the remitted state on return to regular food intake. Control testing produced no significant behavioral effects. Free plasma tryptophan level was negatively correlated with depression score during acute tryptophan depletion. The therapeutic effects of some antidepressant drugs may be dependent on serotonin availability.
Antidepressant and energizing effects of bright light exposure (phototherapy) have been widely reported to occur in patients with seasonal affective disorder. We have attempted to evaluate whether other segments of the population might benefit from phototherapy, most notably individuals with subsyndromal seasonal affective disorder, as well as healthy individuals with no winter difficulties (controls). We have studied 20 subjects in each of these two categories and have found that bright artificial light did not alter mood and behavior in controls. In contrast, individuals with subsyndromal seasonal affective disorder responded favorably to treatment with bright environmental light. A dose of 5 hours of bright light exposure, divided between morning and evening, was more effective than 2 hours of exposure. This finding may have practical implications for establishing optimal environmental lighting conditions for those individuals whose winter difficulties do not meet criteria for seasonal affective disorder.
Patterns of seasonal changes in mood and behavior in Montgomery County, Maryland, were evaluated in randomly selected household samples by lay interviewers using a telephone version of the Seasonal Pattern Assessment Questionnaire. The method for selecting the sample unit was random-digit dialing. We found that 92% of the survey subjects noticed seasonal changes of mood and behavior to varying degrees. For 27% of the sample seasonal changes were a problem and 4.3% to 10% of subjects, depending on the case-finding definition, rated a degree of seasonal impairment equivalent to that of patients with seasonal affective disorder. The seasonal pattern of "feeling worst" exhibited a bimodal distribution with a greater winter and a substantially lower summer peak (ratio, 4.5:1). Younger women who have a problem with seasonal changes and who feel worse on short days tended to exhibit the highest seasonality scores. It is apparent from our study that seasonal affective disorder represents the extreme end of the spectrum of seasonality that affects a large percentage of the general population. The influence of environmental factors on mood disorders and mood changes in the general population might provide valuable insight into pathogenesis, treatment, and prevention of affective illness.
Studies of biological rhythm disorders among manic-depressive patients have suggested that depressed patients may have an early photosensitive interval. If so, exposure to bright light during the photosensitive interval might relieve depressive symptoms. As a test of this hypothesis, 12 depressed patients were exposed to bright white light from roughly 5 to 6 a.m. On the afternoon following this treatment, depressive symptoms were reduced in comparison to baseline ratings and as compared to afternoons following similar exposures to dim red light.
The retina transduces photic stimuli and transmits that information centrally for further processing. This review emphasizes the fact that the nervous system components governing circadian rhythmicity constitute a specialized subdivision of the vertebrate visual system. The brain houses different targets for retinal efferents parcellated according circadian or non-circadian function. Although the suprachiasmatic nucleus (SCN), being the site of the master circadian clock, is necessary for the generation of circadian rhythmicity, precise phase regulation of any rhythm is subject to modulation by SCN-afferent processes. Photic information necessary for entrainment arrives at the SCN via the retinohypothalamic tract. The geniculohypothalamic tract, originating in the intergeniculate leaflet (IGL), provides a secondary route by which photic information can reach the SCN. It also projects extensively to the contralateral IGL and receives reciprocal input from the SCN region. An interaction between the circadian and non-circadian visual systems may exist through connections of the superior colliculus with ventrolateral geniculate leaflet (VLG) and IGL. The SCN, IGL, VLG and superior colliculus are all innervated by serotonin-containing fibers. The following observations are likely to have an impact beyond the rhythm field itself: certain transneuronal tracers label only the circadian visual system; c-fos protein synthesis is induced in the circadian, but not non-circadian, visual system by a phasically active stimulus; blockade of SCN action potentials is unable to alter circadian rhythmicity; transplantation of dispersed fetal SCN cells to arrhythmic adults restores circadian periodicity, but not phase response to light; and the IGL is actually a very extensive part of the lateral geniculate complex.
This study investigated (1) the time-course and durability of antidepressant effects of bright light in winter depressives, and (2) the effects of bright light on mood and behavior in normal controls in a 4-week open treatment paradigm. Twelve subjects in a major depressive episode during recurrent major depressive or bipolar disorder with seasonal pattern and 12 control subjects received 2,500 lux light between 0600 and 0800 hours, while 12 controls arose at 0600 hours for quiet activities without exposure to bright light. In depressives, maximal decrements in depression ratings were not reached until the fourth week of treatment. Four depressives experienced clinically significant hypomanic symptoms. Controls treated with light demonstrated significantly higher clinician ratings of hypomanic symptoms than no-light controls. When depressives and controls were combined, seasonality, but not diagnosis, predicted the emergence of manic-like symptoms. Implications for bright light treatment in the clinical setting are discussed.
A comparison of the baseline and post-infusion effects of the serotonin agonist meta-chlorophenylpiperazine (m-CPP) in 10 patients with seasonal affective disorder (SAD) and 11 healthy control subjects revealed significantly different subjective response profiles between the groups. Several baseline and m-CPP-stimulated responses in symptoms putatively related to serotonergic function changed significantly after a week's exposure to phototherapy in the SAD patients but not the control subjects. Before phototherapy, depressed patients with SAD reported activation-euphoria responses to m-CPP and significant decreases in carbohydrate hunger, but insignificant changes in feeling slowed or sleepy, while control subjects reported no mood or appetite changes but significant increases in feeling slowed down following m-CPP. After phototherapy, which led to a significant reduction in baseline depressive symptom rating to near-euthymic levels in the SAD patients, almost all of the patients' responses to m-CPP were normalized and no longer differed from the control subjects' responses. These results provide evidence of a possible dysregulation in serotonergic neurotransmission in depressed SAD patients that normalizes following treatment with phototherapy.
Reduced light appears to be a key factor in seasonal affective disorder (SAD). This study asks whether the reduced levels of light experienced by elderly persons might result in depression and other SAD symptoms, and how normal elderly persons might respond to bright light interventions similar to those used to treat SAD. In interviews with 140 senior citizens, we found virtually no seasonal variation in mood and behavior and very little depressed affect. Seventeen of these seniors who had good mental and physical health, with no major eye problems, participated in a crossover study of the effects of bright light on both positive and negative affect and sleep. Although sleep did not appear to be affected, the bright light intervention tended to make these normal elderly persons feel worse--more irritable, anxious, and agitated. These findings confirm earlier reports that bright light is not beneficial for normal individuals who are unaffected by seasonal changes.
The authors measured ambient illumination exposure in healthy volunteers in San Diego, California (latitude 32 degrees 43' N, n = 30), and Rochester, Minnesota (latitude 44 degrees 1' N, n = 24), during each of the four quarters of the year, which were centered on the solstices and equinoxes. Subjects wore photosensors on their wrists and lapels (or foreheads while in bed) 24 h per day for an average of 5-6 days per quarter. The maximum of the two illumination readings was stored each minute. Annual average time spent per day in outdoor illumination (> or = 1000 lux) was significantly higher in San Diego than it was in Rochester (p < .04). Daily durations of illumination at or exceeding thresholds of 1, 10, 100, 1000, and 10,000 lux were highly seasonal in the sample as a whole (p < .01 at 1 lux, p < .0001 at other thresholds). Seasonal variation in outdoor illumination was far more pronounced in Rochester than it was in San Diego (interaction p < .001) but remained significant in San Diego (p < or = .03). Seasonal variation in indoor illumination was generally similar in the two cities. The median Rochester subject experienced illumination > or = 1000 lux for 2 h 23 min per day during summer and 23 min per day during winter. The corresponding times in San Diego were 2 h 10 min and 1 h 20 min. Neither age nor gender predicted illumination duration at any level. Both season and geographic location strongly influenced human illumination exposure, and behavior (choice of indoor vs. outdoor environment) was the most important mediating factor.
To review the status of current treatment of seasonal affective disorder (SAD).
Treatment studies of SAD published between January 1989 and March 1995 were identified using a computerized MEDLINE literature search. Additional citations were obtained from the reference sections of these articles. Studies included in this review were selected using operational methodologic criteria.
Many studies support the efficacy of bright light therapy using a fluorescent light box. The best studied protocol is > 2500 lux white light for 2 hours per day, but newer protocols using 10,000 lux for 30 minutes have comparable response rates. Studies of light visors and other head-mounted devices also report similar response rates, but have not yet shown superiority over putative control conditions. There are fewer medication studies in SAD, but controlled studies suggest that fluoxetine, d-fenfluramine and propranolol are effective. Other treatments such as dawn simulation require further study. No studies of psychological treatments for SAD were found. Many studies had methodologic limitations, including brief treatment periods, small sample sizes, and lack of replication, that limit the generalizability of findings.
There are several well-studied, effective treatments for SAD, including light therapy and medications. However, further research must be done to demonstrate sustained treatment response over time, to clarify the intensity-response relationship of light therapy, to clarify the role of light therapy and medications, and to assess combination treatments.
We investigated (1) the mood response of normal women, without a family history of major affective disorder, to acute tryptophan depletion, and (2) the temporal stability of the mood change, within subjects, when rechallenged at least 1 month later. To deplete tryptophan, a tryptophan deficient amino acid mixture was ingested. The control treatment was a nutritionally balanced amino acid mixture containing tryptophan. A marked lowering of plasma tryptophan (80% to 90%) was achieved by both depletions. Compared to the balanced condition, the women exhibited a significant lowering of mood after the first tryptophan depletion on the elation-depression (p < .05), energetic-tired (p < .005), confident-unsure (p < .01), and clearheaded-confused (p < .01) scales of the bipolar profile of mood states. Whereas a lowering of mood was not found in a comparable sample of males studied earlier, these results were similar to those obtained in healthy males at genetic risk for major affective disorder (MAD). Inasmuch as a family history of MAD and female sex are predisposing factors to depression, these results suggest that a mood-lowering response to acute tryptophan depletion may occur preferentially in subjects with a susceptibility to lowered mood. However, the mood response to tryptophan depletion exhibited poor temporal stability in individual subjects.
A dysfunction of the serotonin system may play a major role in the pathogenesis of seasonal affective disorder. Bright light therapy has been shown to be effective in the treatment of winter depression in patients with seasonal affective disorder. Light therapy-induced remission from depression may be associated with changes in brain serotonin function.
After at least 2 weeks of clinical remission, 12 drug-free patients who had had depression with seasonal affective disorder underwent tryptophan depletion in a double-blind, placebo-controlled, balanced cross-over design study.
Short-term tryptophan depletion induced a significant decrease in plasma free and total tryptophan levels (P < .001 for both, repeated measures analysis of variance), with peak effects occurring 5 hours after ingestion of a tryptophan-free amino acid drink. It emerged that tryptophan depletion leads to a transient depressive relapse, which was most pronounced on the day after the tryptophan-depletion testing. No clinically relevant mood changes were observed in the control testing.
The maintenance of light therapy-induced remission from depression in patients with seasonal mood cycles seems to depend on the functional integrity of the brain serotonin system. Our results suggest that the serotonin system might be involved in the mechanism of action of light therapy.
To explore the role of serotonergic system in seasonal affective disorder (SAD), we compared growth hormone (GH) responses to a challenge with a novel 5-HT1D receptor agonist sumatriptan between 11 patients with SAD and nine healthy controls. Of the 11 patients with SAD, nine had repeat sumatriptan challenge following treatment with light therapy. The results showed that GH responses were significantly blunted during winter depression in patients with SAD compared to healthy controls. The GH responses normalized following treatment with light therapy to similar levels in controls. The results of this study provide a support for the role of serotonergic system in pathophysiology of SAD and in the mechanism of action of light therapy.
Little is known about the natural pattern of seasonal and diurnal illumination to which normal people are exposed, especially in northern latitudes. In this study, ambient illumination of normal volunteers living at a latitude of 45 degrees 31' N was recorded with ambulatory photosensors worn for 5 to 6 days in winter and summer. Results from 12 normal subjects (6 men, 6 women) aged 18 to 35 years were included in the analyses. The mean daily duration of time awake was similar in both seasons: 14.6h in the summer and 14.9h in the winter. However, the phase of the sleep-wake cycle was advanced in the summer compared to the winter, as shown by an earlier average waketime and bedtime in the summer. Illumination recorded by the ambulatory monitor between waketime and bedtime was categorized according to four ranges of light intensities: very dim (< 1 lux), dim (1-100 lux), moderate (100-1000 lux), and bright (> 1000 lux) illumination. There was no seasonal difference for the time spent in illumination lower than 1000 lux, but the duration of daily exposure to bright light averaged 2.6h in the summer compared to only 0.4h in the winter (p = 0.0004). To evaluate the diurnal distribution of ambient illumination, time spent awake was divided into four time intervals: morning (waketime to 12:00), afternoon (12:00 to 16:00), early evening (16:00 to 20:00), and late evening (20:00 to bedtime). Except for late evening, the time spent in bright illumination was significantly longer during the summer for all time intervals, but the relative distribution of bright light exposure throughout the day was the same in both seasons. The subjects spent more than 50% of their time awake in illumination dimmer than 100 lux, even in the summer. More naturalistic studies are needed to determine whether very short exposure to bright light or longer exposure to light of moderate intensity (100-1000 lux) are sufficient to maintain circadian entrainment and euthymia in normal young subjects.
Clinical observations and empirical studies suggest that Seasonal Affective Disorder (SAD) is related to personality. The present study estimates the genetic and environmental correlations between the Global Seasonality Score (GSS) from the Seasonal Pattern Assessment Questionnaire and personality measures, assessed using the NEO Five Factor Inventory (NEO-FFI) and the Dimensional Assessment of Personality Pathology (DAPP) in a volunteer sample of 163 monozygotic (MZ) pairs (102 female and 61 male pairs) and 134 dizygotic (DZ) pairs (70 female, 38 male and 26 opposite-sex pairs). Large genetic correlations were found between the GSS and NEO-FFI Neuroticism (0.52: 95% CI = 0.36-0.71) and DAPP-BQ Cognitive Dysregulation (0.50: 95% CI = 0.30-0.71), Affective Lability (0.49: 95% CI = 0.29-0.77), Anxiousness (0.37: 95% CI = 0.18-0.55) and Stimulus Seeking (0.45: 95% CI = 0.25-0.64) scales. The genetic correlations with the remaining scales, such as Extraversion (0.06: 95% CI = -0.16-0.26), Compulsivity (-0.09: 95% CI = -0.31-0.12) and Submissiveness (0.15: 95% CI = -0.05-0.34) were uniformly small. All environmental correlations between the GSS and personality scales were < or = 0.19. These results provide evidence that the observed correlations between these seasonality and personality dimensions are attributable to common genetic factors and that environmental influences are domain specific.
Disturbances of serotonergic neurotransmission appear to be particularly important for the pathophysiology of winter depression. This study investigated whether fluoxetine has antidepressant effects comparable to bright light in the treatment of seasonal affective disorder (winter type).
A randomized, parallel design was used with rater and patients blind to treatment conditions. One week of placebo (phase I) was followed by 5 weeks of treatment (phase II) with fluoxetine (20 mg per day) and a placebo light condition versus bright light (3000 lux, 2 h per day) and a placebo drug. There were 40 patients (20 in each treatment condition) suffering from seasonal affective disorder (SAD) according to DSM-III-R who had a total score on the Hamilton Depression Scale of at least 16.
Forty patients entered phase II and 35 completed it (one drop-out in the fluoxetine group and four in the bright light group). Fourteen (70%) of the patients treated with bright light and 13 (65%) of those treated with fluoxetine were responders (NS). The remission rate in the bright light group tended to be superior (bright light 50%, fluoxetine 25%; P = 0.10). Light therapy improved HDRS scores significantly faster, while fluoxetine had a faster effect on atypical symptoms. Light treatment in the morning produced a significantly faster onset of improvement, but at the end of treatment the time of light application seemed not to be crucial.
Both treatments produced a good antidepressant effect and were well tolerated. An apparently better response to bright light requires confirmation in a larger sample.
Considering the success of bright light therapy in seasonal affective disorders, it was suggested that seasonal mood disorders are triggered by decreased exposure to bright light in the winter; however, no previous studies have used objective measures to assess seasonal patterns of bright light illumination in subjects with seasonal mood variations.
Eleven subjects reporting seasonal mood variations and 8 control subjects had their levels of natural bright light (BL) exposure measured for 5-6 days with an ambulatory monitor during both the summer and winter, at a latitude of 45 degrees 31'N.
Both groups received significantly more BL in the summer than in the winter, but there was no difference between the two groups for the pattern of BL exposure, including total duration, daily distribution, and amplitude of seasonal variation.
These results suggest that complaints of seasonal mood variations are not caused by a differential pattern in bright light exposure compared to normals. It is possible, however, that some individuals are more sensitive than others to variations in natural bright light. Whether an increased vulnerability is due to a more fragile affective state or to a lower sensitivity to light remains to be determined.