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Sleep, Memory, and Plasticity
Abstract
Although the functions of sleep remain largely unknown, one of the most exciting hypotheses is that sleep contributes importantly to processes of memory and brain plasticity. Over the past decade, a large body of work, spanning most of the neurosciences, has provided a substantive body of evidence supporting this role of sleep in what is becoming known as sleep-dependent memory processing. We review these findings, focusing specifically on the role of sleep in (a) memory encoding, (b) memory consolidation, (c) brain plasticity, and (d) memory reconsolidation; we finish with a summary of the field and its potential future directions.
... The relationship between sleep and memory is well-documented, and sleep deprivation can severely impair both declarative and procedural memory. Walker and Stickgold (2006) reviewed studies showing that sleep deprivation disrupts memory consolidation, particularly in tasks requiring verbal or spatial memory. Sleep plays a critical role in consolidating memories formed during wakefulness, and when this process is interrupted, the ability to recall information is significantly impaired. ...
... This reduction in hippocampal activity directly correlates with poorer performance in memory tasks. The mechanism behind this impairment seems to involve disrupted synaptic plasticity, which is crucial for the stabilization of newly acquired memories (Walker & Stickgold, 2006). In addition, sleep deprivation is thought to interfere with the normal processing and integration of information during non-rapid eye movement (NREM) and rapid eye movement (REM) sleep, which are essential stages for memory consolidation (Drummond et al., 2006). ...
... Sleep deprivation affects several brain regions that are critical for cognitive function, particularly the prefrontal cortex and hippocampus. Both of these regions are responsible for higher-order cognitive processes such as memory, attention, and executive function, making them particularly vulnerable to the effects of sleep loss Walker & Stickgold, 2006). As mentioned, the prefrontal cortex shows decreased activity during sleep deprivation, which has been linked to deficits in executive control and attention . ...
Background: Sleep deprivation has become a prevalent issue with potential detrimental effects on cognitive functions, including memory, attention, and emotional regulation. This review aims to synthesize current findings on how insufficient sleep affects cognitive performance and the underlying neurobiological mechanisms involved. Objectives: To examine the impact of sleep deprivation on various cognitive functions, explore its effects on brain structures such as the hippocampus and prefrontal cortex, and understand how these effects vary with age and sleep duration. Methods: This narrative review includes studies from peer-reviewed journals that investigated the cognitive consequences of sleep deprivation. Key studies were selected based on their focus on memory, attention, and emotional regulation, as well as the neurobiological mechanisms involved in these processes. Results: The review identifies consistent findings that sleep deprivation impairs short-term and long-term cognitive functions. Key deficits were observed in working memory, executive function, and emotional processing, with notable changes in brain structures such as the hippocampus and prefrontal cortex. Sleep deprivation’s effects were more pronounced in older adults, whose cognitive vulnerabilities were exacerbated by poor sleep quality.
... Physical activity may influence sleep duration [13], which is itself independently associated with cognitive performance, cognitive decline, and risk of dementia [14][15][16]. Several studies also find sleep stage specific associations with cognitive performance, where rapid eye movement (REM) sleep deprivation is associated with impairments to nondeclarative memory, while non-REM stage III (also referred to as slow wave sleep or SWS) sleep deprivation is associated with impairments to declarative memory [17][18][19][20][21]. Physical activity has been found to promote SWS and delay onset of REM sleep [22][23][24][25]. ...
... SleepNet was used to determine sleep parameters for the longest sleep window over a noon-to-noon interval, with up to 60 min of sleep discontinuity allowed. In the present study, the sleep parameters we examined were overall sleep duration and minutes spent in REM sleep and SWS; we focussed on these parameters based on the large body of evidence suggesting their association with cognitive function [14,[16][17][18][19][20][21]. Overall sleep duration was categorised into short (2-< 6 h) or optimal (≥ 6 h) based on evidence that 6-8 h of sleep per night is optimal for cognitive performance [14]. ...
Background
Previous studies suggest short-term cognitive benefits of physical activity occurring minutes to hours after exercise. Whether these benefits persist the following day and the role of sleep is unclear. We examined associations of accelerometer-assessed physical activity, sedentary behaviour, and sleep with next-day cognitive performance in older adults.
Methods
British adults aged 50-83 years (N = 76) without evidence of cognitive impairment or dementia wore accelerometers for eight days, and took daily cognitive tests of attention, memory, psychomotor speed, executive function, and processing speed. Physical behaviour (time spent in moderate-to-vigorous physical activity [MVPA], light physical activity [LPA], and sedentary behaviour [SB]) and sleep characteristics (overnight sleep duration, time spent in rapid eye movement [REM] sleep and slow wave sleep [SWS]) were extracted from accelerometers, with sleep stages derived using a novel polysomnography-validated machine learning algorithm. We used linear mixed models to examine associations of physical activity and sleep with next-day cognitive performance, after accounting for habitual physical activity and sleep patterns during the study period and other temporal and contextual factors.
Results
An additional 30 min of MVPA on the previous day was associated with episodic memory scores 0.15 standard deviations (SD; 95% confidence interval = 0.01 to 0.29; p = 0.03) higher and working memory scores 0.16 SD (0.03 to 0.28; p = 0.01) higher. Each 30-min increase in SB was associated with working memory scores 0.05 SD (0.00 to 0.09) lower (p = 0.03); adjustment for sleep characteristics on the previous night did not substantively change these results. Independent of MVPA on the previous day, sleep duration ≥ 6 h (compared with < 6 h) on the previous night was associated with episodic memory scores 0.60 SD (0.16 to 1.03) higher (p = 0.008) and psychomotor speed 0.34 SD (0.04 to 0.65) faster (p = 0.03). Each 30-min increase in REM sleep on the previous night was associated with 0.13 SD (0.00 to 0.25) higher attention scores (p = 0.04); a 30-min increase in SWS was associated with 0.17 SD (0.05 to 0.29) higher episodic memory scores (p = 0.008).
Conclusions
Memory benefits of MVPA may persist for 24 h; longer sleep duration, particularly more time spent in SWS, could independently contribute to these benefits.
... The former is thought to occur within hours (Dudai, 2004), whereas there is evidence of the latter occurring within a single day without sleep (Lindsay & Gaskell, 2013), a single period of sleep (Ellenbogen, Hulbert, et al., 2006;Walker & Stickgold, 2006), and as a protracted process taking place over days and weeks (Gais & Born, 2004;. Memory consolidation has been studied for decades in regard to learning language forms (vocabulary and grammar) (Davis, et al., 2009;Gomez, 2006; see Brain and Language special issue, Rasch, ed). ...
... To illustrate, when enhancement is defined as an improvement in the unconscious aspects of the task, such as in the speed of movement, such effects are observed after a period of wake Cohen & Robertson, 2007;Song, et al., 2007). However, conscious knowledge about the task, such as the explicit awareness of the target motor sequence, has been observed to enhance motor performance following a period of sleep (see Walker & Stickgold, 2006, for reviews). ...
Adolescents and young adults with childhood apraxia of speech (CAS) present with persistent speech and language difficulties (Lewis & Ekelman, 2004; Lewis et al., 2007; Preston et al, 2013). These deficits can be a serious barrier to academic and social success (Lewis et al., 2007; Ruben, 2000). Existing models of speech-motor learning focus on active, online practice and the protracted development of the movement component of the speech-motor representation; however, specific elements of the speech-motor representation may be subject to offline learning processes (van Zelst & Earle, 2021). As such, thoughtful timing of speech-motor practice relative to wakeful rest or nocturnal sleep may promote memory consolidation of new speech-motor representations. The aim of this research is to track these learning time courses in adolescents and young adults with and without CAS as they learn a new speech-motor representation. Learning a new speech-motor representation is thought to involve learning both movement-specific (the how of moving) and goal-based information (the why or the reason for moving) (Cohen et al., 2005). These mechanisms can be dissociated and are thought to occur through a division of labor between the procedural and the declarative memory systems (Cohen et al., 2005; Song, 2009; van Zelst & Earle, 2021). Adolescents and young adults with CAS may have deficits in procedural learning (Iuzzini-Seigel, 2021) and thus may have a different division of labor for speech-motor learning relative to those without CAS. The first goal of this project is to investigate the time course of learning the movement (i.e., motor, procedural learning) and goal-based (i.e., linguistic, declarative learning) constituents of a new speech-motor representation in adolescents with (CAS) and without (TD) CAS. Second, these time courses are examined relative to procedural and declarative memory. This work is the first step in a programmatic line of research to optimize the treatment of long-standing CAS in adolescents and young adults.
... For athletes, this creates a cycle that can undermine recovery, performance, and injury prevention. 9 ...
Sleep is a critical determinant of recovery, performance, and overall well-being in athletes. Despite its importance, sleep disturbances—including insomnia, delayed sleep onset, and circadian rhythm disruption—are common in athletic populations, driven by both primary factors (e.g., overtraining, evening workouts, jet lag) and secondary factors (e.g., stress, injury, metabolic conditions). These disturbances can impair physical restoration, hormonal balance, and cognitive functioning. This review explores the physiological foundations of sleep in athletes, outlines the multifactorial causes of insomnia, and evaluates pharmacological strategies—including melatonin, non-benzodiazepine hypnotics, cannabidiol (CBD), and certain antidepressants—for managing sleep disorders. While pharmacotherapy may provide short-term benefits in select situations, non-pharmacological approaches such as Cognitive Behavioral Therapy for Insomnia (CBT-I) remain the gold standard due to their long-term efficacy and minimal side effects. An integrated, personalized approach that combines behavioral, physiological, and pharmacological strategies offers the greatest potential for optimizing sleep and supporting sustainable athletic performance.
... Thus, organotypic cultures provide a unique opportunity to study dynamic regimes associated with prediction, timing, and replay-which have typically only been studied in vivo. Replay is generally defined as the spontaneous reactivation of activity patterns during resting or sleep states that mirror the spatiotemporal structure of activity that occurred during prior learning or behavior [36][37][38][39][40][41][42][43] . These "offline" spontaneous reactivations of patterned activity observed during the recent waking experience is in itself a form of network-level learning and may serve a purpose in the consolidation of memories or information by further engaging neural plasticity and synaptic restructuring mechanisms. ...
It has been proposed that prediction and timing are computational primitives of neocortical microcircuits, specifically, that neural mechanisms are in place to allow neocortical circuits to autonomously learn the temporal structure of external stimuli and generate internal predictions. To test this hypothesis, we trained cortical organotypic slices on two temporal patterns using dual-optical stimulation. After 24-h of training, whole-cell recordings revealed network dynamics consistent with training-specific timed prediction. Unexpectedly, there was replay of the learned temporal structure during spontaneous activity. Furthermore, some neurons exhibited timed prediction errors as revealed by larger responses when the expected stimulus was omitted compared to when it was present. Mechanistically our results indicate that learning relied in part on asymmetric connectivity between distinct neuronal ensembles with temporally-ordered activation. These findings further suggest that local cortical microcircuits are intrinsically capable of learning temporal information and generating predictions, and that the learning rules underlying temporal learning and spontaneous replay can be intrinsic to local cortical microcircuits and not necessarily dependent on top-down interactions.
... Sleep is necessary for the processing of newly acquired information and facilitating consolidation of memories into long-term storage [6][7][8][9] . In rodents, both the quality and quantity of sleep is important for learning and memory with artificial enhancement or deprivation of sleep improving or impairing performance, respectively, on a variety of memory tasks 2,6,10-12 . ...
Age-related sleep disruption is common in older adults. Not only does the total amount of time spent in sleep decline, but the number of arousals during sleep increases with age. As sleep is important for both memory consolidation and to prevent neurodegenerative pathology, this decline in sleep and/or sleep consolidation may underlie age-related cognitive decline and dementias. Furthermore, treatment of sleep disruption can improve quality of life. However, few interventions have successfully reversed age-related sleep decline. Extracts from the plant Centella asiatica have demonstrated neuroprotective effects in human, rodent, and fly models of aging and neurodegenerative diseases, and is a promising intervention for dementias, yet little is known about how these extracts affect sleep patterns. Here, we administered Centella asiatica water extract ( CAW) dosed or control chow to male and female C57BL6/J mice aged 18 months. Effects on sleep composition were determined using electrodes that recorded EEG and EMG signals. We found that CAW dosed chow (1000 mg/kg/day) increased REM sleep time in aged male mice and decreased the number of arousals during sleep observed in aged females, compared to age- and sex-matched controls. We conclude that CAW administered in food has a moderate, sex-dependent effect on sleep quantity and quality.
Statement of Significance
Sleep declines with age and may underline age-related cognitive changes. However, few interventions have successfully reversed age-related sleep and cognitive decline. This study found that botanical extract from the plant Centella asiatica increased total REM sleep time in aged male mice, and decreased sleep fragmentation in aged female mice, compared to age- and sex-matched controls. Whether these moderate, sex-dependent effect sizes on sleep in aged mice are impactful enough to affect cognition, quality of life, and/or neurodegenerative pathology could be explored in future studies.
... However, 27.5% of adults do not meet the PA levels recommended by the World Health Organization (WHO) in 2010 11 , and little improvement has been observed over the past decade 9 . In addition to PA, sleep is also an important factor affecting the MH of university students 12,13 . Research has found that short-term sleep deprivation reduces efficiency in learning, weakens cognitive functioning, and prolongs reaction time 14,15 . ...
Objective
This study aimed to examine the levels of physical activity (PA), sleep, and mental health (MH), specifically depression, anxiety, and stress, among Chinese university students. It also aimed to analyze the influencing factors of MH, providing a theoretical foundation for developing intervention programs to improve college students’ mental health.
Methods
A stratified, clustered, and phased sampling method was employed. In September 2022, a survey was conducted among 36,756 university students from 104 higher education institutions across 31 provinces, autonomous regions, and municipalities in China. The participants’ PA behaviors, sleep patterns, depressive symptoms (use the CES-D), anxiety symptoms (use the GAD-7), smoking and drinking behaviors, and demographic information were assessed through an online questionnaire using Questionnaire Star software.
Results
A total of 30,475 valid questionnaires were completed. The proportion of university students engaging in light-intensity PA was 77.6%. The prevalence of insufficient sleep was 39.5%, whereas the prevalence of poor sleep quality was 16.7%. The prevalence of depressive symptoms was 10%, and the prevalence of anxiety symptoms was 23.3%. Binary logistic regression analysis revealed that engaging in moderate to high-intensity PA and having sufficient and high-quality sleep were associated with a lower likelihood of depressive symptoms (OR = 0.207–0.800, P < 0.01), whereas appropriate sleep duration and higher sleep quality were associated with a lower likelihood of anxiety symptoms (OR = 0.134–0.827, P < 0.001).
Conclusion
The intensity of PA among university students is predominantly light, and the reported rate of insufficient sleep is relatively high. Moderate to high-intensity PA and sufficient high-quality sleep may alleviate MH issues among college students, with an interaction effect observed among PA, sleep, and depression symptoms. Future studies should further explore targeted interventions combining PA and sleep behaviors to enhance the MH of university students.
... 10 Chronic sleep deprivation or a lack of opportunities for sleep can have adverse effects on cognitive functions, including impaired concentration, compromised memory, and heightened irritability. 11,12 Consequently, insomnia is often associated with daytime fatigue, diminished academic performance, and reduced overall quality of life. 13 Depression and Its Association with Insomnia Depression, as another psychiatric issue significantly affecting the mental well-being of college students, has been shown to be closely associated with insomnia. ...
Purpose
In China, stringent and long-lasting infection control measures, which were called “dynamic zero-COVID policy”, have significantly affected the mental health of college students, particularly concerning depressive and insomnia symptoms. This study aims to investigate how depressive and insomnia symptoms evolved among Chinese college students throughout the pandemic, including the beginning and end of the dynamic zero-COVID policy period.
Patients and Methods
We conducted a 2-years longitudinal survey involving 1102 college students, collecting data at three key time points. Depressive symptoms were assessed using the Patient Health Questionnaire-9, and insomnia symptoms were measured with the Youth Self-rating Insomnia Scale-8. Three contemporaneous symptom networks and two cross-lagged panel networks were constructed.
Results
In the current sample, the prevalence of clinically significant depressive symptoms was 6.1%, 8.9%, and 7.7% during the first, second, and third waves, respectively. The prevalence of clinically significant insomnia symptoms was 8.1%, 13.0%, and 14.1%. Over time, the severity of depressive and insomnia symptoms and network density increased, persisting at least one year after the pandemic and control measures ended. “Difficulty initiating sleep” bridged the two disorders, while “anhedonia” played a pivotal role in triggering and sustaining other symptoms.
Conclusion
This study underscores the lasting impact of the evolving zero-COVID policy on depressive and insomnia symptoms among college students, elucidating the underlying interaction mechanisms. There is a pressing need for a more comprehensive evaluation of the implementation of restrictive public policies, taking into account their potential long-term consequences.
... (Carskadon & Dement, 2005). Uyku sırasında beyin, non-REM (NREM) ve REM evrelerinde nörotransmiter aktivitelerle sinaptik temizlik ve hafıza pekiştirme gibi işlevleri yerine getirir (Walker & Stickgold, 2006). Uyku eksikliği durumunda kortizol seviyeleri artış göstererek stres yanıtlarını tetikler ve bağışıklık fonksiyonlarını zayıflatabilir, bu da metabolik ve nörolojik hastalıklara yatkınlığı artırabilir (Meerlo ve ark., 2008). ...
Bu bölümde, uykunun bilişsel ve fiziksel performans üzerindeki etkileri kapsamlı bir şekilde ele alınmıştır. Uyku, zihinsel ve fiziksel işlevlerin sürdürülebilirliği ve gelişimi için temel bir biyolojik süreç olarak değerlendirilmekte olup, düzenli ve kaliteli uykunun öğrenme, hafıza pekiştirme, ruh hali düzenleme ve psikolojik iyi oluş üzerinde olumlu etkileri olduğu vurgulanmaktadır. Buna karşılık, yetersiz uyku süresi ve düşük uyku kalitesinin özellikle prefrontal korteks aracılığıyla dikkat, hafıza ve işlem hızı gibi yürütücü işlevleri olumsuz etkilediği, ayrıca Alzheimer hastalığı gibi nörodejeneratif hastalıklar için risk faktörü oluşturduğu belirtilmektedir. Fiziksel performans açısından değerlendirildiğinde, yeterli uyku süresinin dayanıklılık, reaksiyon süresi ve genel fiziksel verimlilik üzerinde kritik bir rol oynadığı, uyku eksikliğinin ise kas aktivasyonu, reaksiyon süresi ve dayanıklılığı olumsuz etkilediği ifade edilmektedir. Tek bir gecelik uyku yoksunluğunun dahi atletik performansta düşüşe yol açtığı, ayrıca hormonal dengenin bozulmasına, iştah artışına ve vücut kitle indeksinde yükselmeye neden olarak obezite ve metabolik rahatsızlık riskini artırabileceği vurgulanmaktadır. Sonuç olarak, uykunun bilişsel süreçlerin sağlıklı işleyişi, fiziksel dayanıklılık ve genel sağlık açısından hayati bir işlev olduğu, bu nedenle eğitim, çalışma ve antrenman programlarının uyku düzenini optimize edecek şekilde düzenlenmesi ve bireylerin uyku sağlığı konusunda bilinçlendirilmesinin bilişsel ve fiziksel performansı artırmada önemli olduğu ifade edilmektedir. Uyku süresinin ve kalitesinin iyileştirilmesi, bireylerin bilişsel kapasitelerini geliştirmelerine, fiziksel performanslarını artırmalarına ve sağlıklı bir yaşam sürdürmelerine katkı sağlayabilir.
... Strictly speaking, this can be regarded as a new learning process. In addition, (re)consolidation of what has been learned also takes place increasingly during phases of sleep (Diekelmann & Born, 2010;Walker & Stickgold, 2006). This suggests that future research on the time course of IFBL may need to consider what happens during sleep after a learning experience. ...
Informal field-based learning (IFBL)—a subset of work-related learning that is informal, intentional, and self-directed—is a developmental process in which motivational, behavioral, and cognitive mechanisms interact. Despite the consensus on the role of cognitive processing in learning, research on informal learning is dominated by a behavioral focus on learning activities, while the cognitive perspective remains sidelined. In the Self-regulated Informal Learning Cycle we introduce here, we use metacognitive and memory system lenses to zoom into the (meta-)cognitive IFBL processes, considering intention as a motivational starting point of the learning process. Specifically, we draw on self-determination theory, achievement goal theory, memory concepts, and self-regulated learning models. Our cycle distinguishes five phases—preparation, action, encoding and consolidation, performance, and self-appraisal—and elaborates on IFBL processes at the intentional, behavioral, cognitive, and metacognitive level. Theoretical implications for human resource development, including the often-neglected role of time in IFBL, are discussed.
... By school age, the establishment of a sleep schedule becomes important. Rapid eye movement (REM) sleep is essential for the processes of short-term memory (148,(152)(153)(154). Sleep that includes REM, as well as non-REM states, is crucial to synaptic development, the support of cognitive functions, memory and plasticity (memory encoding, unification and reunion) (155)(156)(157). The process of pruning during sleep converts short-term to long-term memories. ...
... Poor sleep quality, characterized by fragmented or non-restorative sleep, is strongly associated with mental health challenges such as depression and anxiety, as highlighted in [8]. Moreover, disrupted sleep has been shown to elevate inflammatory markers, increasing susceptibility to chronic illnesses, including cardiovascular diseases and diabetes [9]. Disturbances in sleep patterns or sleep quality have been associated with a myriad of health problems, including metabolic disorders, cardiovascular diseases, impaired immune function, and neurodegenerative conditions [10]. ...
Background/Objectives: This study aims to investigate the effects of ethylene oxide (EO) exposure on sleep health, focusing on sleep duration and quality. Methods: The study analyzed data from the NHANES (National Health and Nutrition Examination Survey) 2015–2020 cycles, including 4268 participants aged 20 and older. EO exposure was measured using hemoglobin adducts of EO (HbEO), which serve as a reliable biomarker. Sleep health was assessed through self-reported questionnaires on sleep duration and quality. Participants were categorized based on sleep duration (<6 h, 6–9 h, >9 h) and symptoms of sleep disturbances. Statistical analyses employed survey-weighted logistic regression models to evaluate the associations between HbEO levels and sleep outcomes, adjusting for sociodemographic, health-related, and behavioral factors. Moreover, to examine whether the impact of ethylene oxide exposure on sleep quality and sleep duration varies by sociodemographic characteristics, stratified analyses were conducted based on gender, age, marital status, and employment type. Results: According to the results, higher EO exposure was associated with shorter sleep durations and increased likelihood of sleep disturbances. Moreover, according to sub-group analysis by sex, men with higher exposure to EO, were likely to have short sleep duration, and women with higher exposure to EO had higher risk of daytime sleepiness and sleep problems. Conclusions: The findings suggest that EO exposure may negatively impact sleep health, emphasizing the need for stricter EO exposure regulations and public health interventions to reduce associated risks.
... Brain mechanisms associated with REM dreaming are clearly consistent with production of mental simulations of counterfactual, bizarre and extraordinary SAs. During REM dreaming external sensory input is reduced, cholinergic and dopaminergic activity levels are high, while serotoninergic and noradrenergic levels are low or absent, thus enhancing brain plasticity and pushing the brain-mind into a visually and emotionally driven, hyper-associative state (Hutchison and Rathore, 2015;Llewellyn, 2016;Pace-Schott and Hobson, 2002;Walker and Stickgold, 2006). In addition, brain regions dynamically modulated during REM tend to strictly obey principles of TPM: fMRI and rCBF scanning with simultaneous EEG scalp recordings of healthy participants asleep in the scanner demonstrate selective activation of the pontine tegmentum, thalamic nuclei, several limbic elements including the amygdala and the hippocampus, anterior cingulate cortex, mediobasal prefrontal lobes, and extrastriate cortex (Dang-Vu et al., 2010;Maquet et al., 1996;Fox et al., 2013). ...
We review and synthesize recent religion and brain studies and find that at a broad network neuroscience level, religious/spiritual experiences (RSEs) appear to depend crucially upon interactions between the default mode network (DMN), the frontoparietal network (FPN), and the salience network (SN). We see this general result as broadly consistent with Menon’s et al. “Triple Network or Tripartite Model” (TPM) of neuropsychiatric function/dysfunction. A TPM cycling model is here offered to account for details of neural bases of an array of RSE phenomena including ecstatic seizures, neuroimaging of religious participants, psychedelically induced mystical states and perceptions of supernatural agents. To adequately account for SA perceptions, however, recent evidence suggests that REM sleep and dreaming mechanisms likely play a role. Future research should examine neurodevelopmental mechanisms of acquired SA perceptions as well as societal-level effects such as brain mediated religious beliefs of in-group cohesion and out-group hostility.
... This indicates that although the pre-frontal location of the wearable electrodes does not affect the ability to capture the spindle-associated brain activity originating from deep brain regions, the relatively low correlation in spindle frequency (0.48), implies that the location may affect the temporal frequency of captured sleep spindle features. Since sleep spindles may be described as a propagating wave with frequency modulation [39][40][41] , different locations of electrodes may capture different aspects of the sleep spindle. In other words, owing to differences in sleep spindle topographical distributions across the skull, their features may be captured differently from different locations. ...
Polysomnography, the gold standard diagnostic tool in sleep medicine, is performed in an artificial environment. This might alter sleep and may not accurately reflect typical sleep patterns. While macro-structures are sensitive to environmental effects, micro-structures remain more stable. In this study we applied semi-automated algorithms to capture REM sleep without atonia (RSWA) and sleep spindles, comparing lab and home measurements. We analyzed 107 full-night recordings from 55 subjects: 24 healthy adults, 28 Parkinson's disease patients (15 RBD), and three with isolated Rem sleep behavior disorder (RBD). Sessions were manually scored. An automatic algorithm for quantifying RSWA was developed and tested against manual scoring. RSWAi showed a 60% correlation between home and lab. RBD detection achieved 83% sensitivity, 79% specificity, and 81% balanced accuracy. The algorithm accurately quantified RSWA, enabling the detection of RBD patients. These findings could facilitate more accessible sleep testing, and provide a possible alternative for screening RBD.
... Reports from both college students and graduate schools indicate insufficient sleep or decreased subjective sleep quality (Becker et al., 2018). Sleep deprivation can adversely affect cognitive function (Walker & Stickgold, 2006). Further evidence underscores the importance of longer, more regular sleep patterns in positively contributing to college students' academic achievement (Okano, Kaczmarzyk, Dave, Gabrieli, & Grossman, 2019). ...
... The morphological dynamics of neurons are believed to contribute to processes of memory and neural plasticity 3,32,33 , but it is unclear whether these dynamics are different between awake and sleep states even though sleep is hypothesized to be specifically involved in certain stages of memory processes 38,39 . Pioneering studies by EM and in vivo TPM imaging indeed reported such differences in synaptic connections 40 and turnover rate of dendritic spines [41][42][43] , respectively. ...
Neurons are best studied in their native states in which their functional and morphological dynamics support animals’ natural behaviors. Super-resolution microscopy can potentially reveal these dynamics in higher details but has been challenging in behaving animals due to severe motion artifacts. Here we report multiplexed, line-scanning, structured illumination microscopy, which can tolerate motion of up to 50 μm s⁻¹ while achieving 150-nm and 100-nm lateral resolutions in its linear and nonlinear forms, respectively. We continuously imaged the dynamics of spinules in dendritic spines and axonal boutons volumetrically over thousands of frames and tens of minutes in head-fixed mouse brains during sleep–wake cycles. Super-resolution imaging of axonal boutons revealed spinule dynamics on a scale of seconds. Simultaneous two-color imaging further enabled analyses of the spatial distributions of diverse PSD-95 clusters and opened up possibilities to study their correlations with the structural dynamics of dendrites in the brains of head-fixed awake mice.
... Sleep is a highly conserved phenomenon that subserves multiple functions, including to promote learning and memory [1][2][3][4][5][6][7][8]. The visual system provides an attractive model system that has been used to study the role of sleep in consolidating multiple forms of experience-dependent plasticity in vivo. ...
Study Objectives
Repeated exposure to familiar visual sequences drives experience-dependent and sequence-specific plasticity in mouse primary visual cortex (V1). Prior work demonstrated a critical role for sleep in consolidating a related but mechanistically distinct form of experience-dependent plasticity in V1. Here, we assessed the role of sleep in consolidation of spatiotemporal sequence learning (sequence plasticity) in mouse V1.
Methods
Visually evoked potentials (VEPs) were recorded in awake, head-fixed mice viewing sequences of four visual stimuli. Each sequence was presented 200 times per session, across multiple sessions, to drive plasticity. The effects of sleep consolidation time and sleep deprivation on plasticity were assessed.
Results
Sequence plasticity occurred in V1 following as little as one hour of ad libitum sleep and increased with longer periods of sleep. Sleep deprivation blocked sequence plasticity consolidation, which recovered following subsequent sleep.
Conclusions
Sleep is required for the consolidation of sequence plasticity in mouse V1.
... Sleep plays a pivotal role in enhancing daily well-being and optimizing mental and physical processes [25]. Over the years, there has been increasing interest in delving into how sleep correlates with the brain's operations, especially how sleep deprivation might hinder cognitive functions [26][27][28]. In this context, the brain's glymphatic system has emerged as a fo-cal point due to its association with sleep. ...
... Certain dietary components, such as tryptophan, magnesium, and vitamin B6, have been shown to promote better sleep quality [21]. Quality sleep positively impacts psychological balance and is essential for memory consolidation and cognitive maintenance [42]. Thus, a healthy diet fosters psychological balance through various pathways, indirectly promoting cognitive function. ...
Background
This study aims to investigate the relationships between the Chinese Healthy Eating Index (CHEI), psychological balance, depressive symptoms, and cognitive function in the rural older population. Additionally, it examines the impact of CHEI on cognitive function and the potential chain mediating roles of psychological balance and depressive symptoms.
Methods
The study utilized data from 2,552 rural older adults aged 65 and above, drawn from the Chinese Longitudinal Healthy Longevity Study (CLHLS). The CHEI was self-reported, with scores ranging from 0 to 50, representing adherence to healthy eating habits. Psychological balance was assessed using status and personality-emotion characteristics recorded in the database, with scores ranging from 6 to 30. Cognitive function was measured using the Mini-Mental State Examination (MMSE), with scores ranging from 0 to 30; higher scores indicated better cognitive function. Depressive symptoms were evaluated using the 10-item Center for Epidemiologic Studies Depression Scale (CESD-10), with scores ranging from 0 to 30, where higher scores reflected more severe depressive symptoms.
Results
The median CHEI score was 40.0 (IQR: 34.0–45.0), reflecting moderate adherence to healthy dietary practices. The median Psychological Balance score was 19.0 (IQR: 17.0–21.0), and the median Depressive Symptoms score was 13.0 (IQR: 10.0–15.0), indicating mild depressive symptoms among participants. Additionally, the median Cognitive Function score was 28.0 (IQR: 27.0–29.0), suggesting relatively stable cognitive abilities within the sample. Correlational analysis revealed the following: (1) Depressive symptoms were negatively correlated with both cognitive function (rs = -0.100, p < 0.001) and CHEI (rs = -0.206, p < 0.001), as well as with psychological balance (rs = -0.142, p < 0.001). (2) CHEI was positively correlated with both cognitive function (rs = 0.144, p < 0.001) and psychological balance (rs = 0.131, p < 0.001). (3) Cognitive function was also positively correlated with psychological balance (rs = 0.096, p < 0.001). Mediation analysis demonstrated that both psychological balance and depressive symptoms partially mediated the relationship between CHEI and cognitive function, forming a chain-mediating effect.
Conclusion
The Chinese Healthy Eating Index was found to have a direct positive impact on cognitive function in rural older adults. Furthermore, it exerted an indirect effect through the independent and chain-mediating roles of psychological balance and depressive symptoms. These findings suggest that dietary adherence can influence cognitive health not only directly but also by improving psychological well-being and reducing depressive symptoms.
... Sleep is an important biological function and critical to maintain homeostasis and sleep disturbances are a major risk factor for cardiovascular disease, metabolic disorders and mortality (1). Chronic sleep disturbances adversely affect neurological functioning such as memory formation (2), sustained attention (3) and other higher cognitive functions (4), as well as strongly associated with the development of Alzheimer's disease (5). In children and young adults, disturbed sleep is reportedly associated with mental health disorders (6), depression (7) and impaired academic performance (8). ...
The most common source of Radiofrequency Electromagnetic Field (RF-EMF) exposures during sleep includes digital devices, yet there are no studies investigating the impact of multi-night exposure to electromagnetic fields emitted from a baby monitor on sleep under real-world conditions in healthy adults. Given the rise in the number of people reporting to be sensitive to manmade electromagnetic fields, the ubiquitous use of Wi-Fi enabled digital devices and the lack of real-world data, we investigated the effect of 2.45 GHz radiofrequency exposure during sleep on subjective sleep quality, and objective sleep measures, heart rate variability and actigraphy in healthy adults. This pilot study was a 4-week randomised, double-blind, crossover trial of 12 healthy adults. After a one-week run-in period, participants were randomised to exposure from either an active or inactive (sham) baby monitor for 7 nights and then crossed over to the alternate intervention after a one-week washout period. Subjective and objective assessments of sleep included the Pittsburgh Insomnia Rating Scale (PIRS-20), electroencephalography (EEG), actigraphy and heart rate variability (HRV) derived from electrocardiogram. Sleep quality was reduced significantly (p < 0.05) and clinically meaningful during RF-EMF exposure compared to sham-exposure as indicated by the PIRS-20 scores. Furthermore, at higher frequencies (gamma, beta and theta bands), EEG power density significantly increased during the Non-Rapid Eye Movement sleep (p < 0.05). No statistically significant differences in HRV or actigraphy were detected. Our findings suggest that exposure to a 2.45 GHz radiofrequency device (baby monitor) may impact sleep in some people under real-world conditions however further large-scale real-world investigations with specified dosimetry are required to confirm these findings.
... Sleep, particularly during the REM phase, is instrumental in consolidating both declarative and non-declarative memories, which are fundamental for academic and cognitive performance (Curcio et al., 2006). Furthermore, the quality and quantity of sleep are closely linked to enhanced cognitive functioning, as they support neuroplasticity, a critical process for long-term memory consolidation and retention of newly acquired information (Walker & Stickgold, 2006). Additionally, autonomic modulation, measured in the study sample through HRV variables such as HR and rMSSD, suggests that their increase in these variables is indicative of enhanced parasympathetic modulation. ...
This study analyzed gender differences in the psychophysiological factors of stress and academic performance among university students. A cross-sectional design was employed with a sample of 601 university students (74.7% women) aged 15 to 47 years. Participants completed assessments on sleep quality, heart rate variability (HRV), personality traits, and psychological indicators such as anxiety, depression, and perceived stress. Results showed that women exhibited higher levels of neuroticism, anxiety, psychological inflexibility, and perceived stress compared to men, yet achieved better academic performance. Regression analysis revealed that sleep quality and HRV parameters, such as heart rate (HR) and the square root of the mean squared differences of successive NN intervals (rMSSD), were positively associated with academic achievement. Despite higher stress levels, female students seemed to employ more effective emotional regulation strategies, contributing to their academic success. These findings highlight the need for gender-sensitive approaches in stress management interventions to improve student well-being and academic outcomes. Future research should consider longitudinal designs to explore the temporal dynamics of stress and academic performance.
... El espacio soterrado de la casa, además de ser un repositorio directo de muchas experiencias, es esencialmente el dormitorio de la vivienda; el lugar donde precisamente los sueños ordenan la memoria. La investigación de Matthew P. Walker y Robert Stickgold demuestra que el sueño REM juega un papel activo en la consolidación de la memoria 16 . Estos autores, y muchos otros, resaltan cómo nuestras experiencias diurnas se procesan y se integran durante el sueño en un proceso paralelo al modo en que las vivencias se depositan y entrelazan con el espacio habitado 17 . ...
Entre 1964 y 1966 el arquitecto japonés Kazuo Shinohara diseñó y construyó una vivienda en Tokio, que él mismo denominó Casa de la Tierra. Se trata de una pequeña casa que, gracias a su singular configuración espacial y formal, representa el punto culminante en el interés que Shinohara había desarrollado a propósito del potencial creativo y emotivo que posee la tierra. El objetivo de este artículo es examinar el tratamiento arquitectónico y material de la tierra que el arquitecto implementa a través de esta vivienda. Se busca exponer los mecanismos espaciales que Shinohara emplea para desplegar el proyecto, y el modo en que estos condensan en una emocionante relación entre el acto de habitar la tierra y la memoria del habitante.
... By school age, the establishment of a sleep schedule becomes important. Rapid eye movement (REM) sleep is essential for the processes of short-term memory (148,(152)(153)(154). Sleep that includes REM, as well as non-REM states, is crucial to synaptic development, the support of cognitive functions, memory and plasticity (memory encoding, unification and reunion) (155)(156)(157). The process of pruning during sleep converts short-term to long-term memories. ...
The Econeurobiology of the brain describes the environment in which an individual’s brain develops. This paper explores the complex neural mechanisms that support and evaluate enrichment at various stages of development, providing an overview of how they contribute to plasticity and enhancement of both achievement and health. It explores the deep benefits of enrichment and contrasts them with the negative effects of trauma and stress on brain development. In addition, the paper strongly emphasizes the integration of Gardner’s intelligence types into the school curriculum environment. It emphasizes the importance of linking various intelligence traits to educational strategies to ensure a holistic approach to cognitive development. In the field of Econeurobiology, this work explains the central role of the environment in shaping the development of the brain. It examines brain connections and plasticity and reveals the impact of certain environmental factors on brain development in early and mid-childhood. In particular, the six key factors highlighted are an environment of support, nutrition, physical activity, music, sleep, and cognitive strategies, highlighting their potential to improve cognitive abilities, memory, learning, self-regulation, and social and emotional development. This paper also investigates the social determinants of health and education in the context of Econeurobiology. It emphasizes the transformative power of education in society, especially in vulnerable communities facing global challenges in accessing quality education.
... These mechanisms encompass possible shifts in brain volume, changes in brain connectivity, the buildup of neurodegenerative proteins, and disturbances in glymphatic drainage [67,68]. During sleep, the brain undergoes various processes that are essential for memory consolidation, synaptic plasticity, and overall cognitive recovery [69,70]. Disruptions in sleep patterns, such as insufficient sleep duration, can impair these processes, leading to deficits in complex cognition [71]. ...
This study aimed to examine the associations between specific sleep parameters and
specific aspects of cognitive functioning in individuals diagnosed with mild cognitive impairment (MCI), compared with healthy controls (HCs) by using cognitive, subjective, and objective sleep measures. A total of 179 participants were enrolled, all aged ≥ 65 years (mean age = 70.23; SD = 4.74)and with a minimum of six years of education (mean = 12.35; SD = 3.22). The sample included 46 HCs (36 females), 75 individuals with amnestic MCI (aMCI) (51 females), and 58 individuals with non-amnestic MCI (naMCI) (39 females). Inhibition, cognitive flexibility as a combined application of inhibitory control and set shifting or task/rule switching, and planning were examined. The following D-KEFS subtests were administered for their evaluation: Verbal Fluency Test, Color–Word Interference Test, and Tower Test. Self-reported sleep questionnaires (Athens Insomnia Scale, Stop-Bang questionnaire, and Pittsburg Sleep Quality Index) were used for subjective sleep assessments. Actigraphy was used for objective sleep measurements. Mixed-measures ANOVA, MANOVA, and one-way ANOVA, as well as the Scheffe post hoc test, were applied to the data. The results showed that the three groups exhibited statistically significant differences in the Tower Test (total achievement score, total number of administered problems, and total rule violations). As regards objective sleep measurements, the total sleep time (TST) was measured using actigraphy, and indicated that there are significant differences, with the HC group having a significantly higher mean TST compared to the naMCI group. The relationships evaluated in the TST Tower Test were found to be statistically significant. The findings are discussed in the context of potential parameters that can support the connection between sleep duration, measured as TST, and cognitive planning, as measured using the Tower Test.
... The two 'treatment groups' were asked to watch real training videoclips, in the morning or just before bedtime. In fact, the effect of sleep on memory consolidation was also explored [23]. ...
This study explored the impact of lifestyle habits and sensory processing patterns on sleep quality by analyzing body movements (BMs) during the first and last 3 h of sleep in toddlers. We collected cross-sectional data about sleep-related habits from 58 toddlers using a mobile application. Actigraphy measured BMs during nighttime sleep and 1 h before bedtime, as well as sleep latency, over 8 consecutive days. The Infant/Toddler Sensory Profile was used to assess the toddlers’ sensory processing patterns. The participants had a mean age of 22.0 ± 2.0 months. BMs were significantly lower during the first 3 h of sleep. Longer sleep latency was significantly associated with media use and higher activity levels before bedtime. Ending a nap earlier and consuming a substantial breakfast were correlated with lower BMs during the first 3 h of sleep. Auditory and oral sensory scores were positively correlated with BMs during the first 3 h of sleep. However, no specific factors related to lifestyle habits or sensory processing patterns were found to correlate with BMs during the last 3 h of sleep. Lifestyle habits and sensory processing patterns have a significant impact on toddlers’ sleep quality, emphasizing the importance of appropriate routines and environments.
With a growing population of employees moving from traditional to home offices and loneliness becoming a global concern, we seek to examine daily predictors of workplace loneliness among full-time remote workers. In this study, we propose that sleep as a source of vigor provides employees with sufficient resources to engage in workplace interactions with coworkers, which helps reduce their feeling of workplace loneliness. We tested our prediction about the indirect effect of sleep quality on loneliness using a sample of 107 employees working fully remotely prior to the COVID-19 pandemic and a sample of 135 employees working remotely full time during the first wave of the COVID-19 pandemic. In both samples, we surveyed employees for 5 consecutive workdays, measuring their sleep quality at night, vigor in the morning, the amount of interaction with coworkers during the workday, and workplace loneliness during the day. The results indicated that for employees who were sent to work fully remotely due to the pandemic, but not for employees who chose to work remotely prior to the pandemic, higher-quality sleep was related to reduced workplace loneliness indirectly, via increased morning vigor and interactions with coworkers during the day.
Research suggests that the spatial profile of slow wave activity (SWA) could be altered in hypersomnolence. Slow oscillations (SOs; 0.5–1.5 Hz), single waveform events contributing to SWA, can be labelled as Global, Frontal, or Local depending on their presentation on the scalp. We showed that SO space–time types differentiate in their amplitudes, coordination with sleep spindles, and propagation patterns. This study applies our data‐driven analysis to the nocturnal sleep of adults with and without hypersomnolence and major depressive disorder (MDD) to explore the potential relevance of SO space–time patterns as hypersomnolence signatures in the sleep EEG. We leverage an existing dataset of nocturnal polysomnography with high‐density EEG in 83 adults, organised in four groups depending on the presence/absence of hypersomnolence and on the presence/absence of MDD. Group comparisons were conducted considering either two groups (hypersomnolence status) or the four groups separately. Data shows enhanced Frontal SO activity compared with Global activity in hypersomnolence, with or without MDD, and a loss of Global SO amplitude at central regions in hypersomnolence without MDD compared to controls. As Global SOs travel fronto‐parietally, we interpret these results as likely driven by a loss of coordination of Global SO activity in hypersomnolence without MDD, resulting in an overabundance of Frontal SOs. This study suggests that characteristics of Frontal SO and Global SOs may have the potential to differentiate individuals with hypersomnolence without MDD, and that the space–time organisation of SOs could be a mechanistically relevant indicator of changes in sleep brain dynamics related to hypersomnolence.
This study aimed to examine the relationship between substance use and memory disorders. This study also analyzed the biological effects of drug use on the brain and investigated the mechanisms by which these effects lead to impairment of memory function. Furthermore, the impact of various elements, including substance abuse, mental health conditions, hereditary susceptibility, and chronological age, was assessed. Substance use negatively affects memory and learning processes by causing functional impairments in critical regions such as the hippocampus and frontal lobe. Different substances cause specific damage to the memory. This review highlights how substance use can lead to permanent neurocognitive impairment, with effects varying according to substance type, duration of use, and individual factors. This underscores the importance of early intervention and preventive strategies. Multidisciplinary approaches are important in the prevention and management of these effects.
Sleep is a ubiquitous process that has been conserved in animals. Yet, our understanding of the functions of sleep largely derives from a few species. Sleep is considered to play an important role in mental processes, including learning and memory consolidation, but how widespread this relationship is across taxa remains unclear. Here, we test the impact of sleep disruption on the ability of the cleaner fish ( Labroides dimidiatus ) to both learn and remember a novel cognitive task. Sleep was disrupted by exposing a subset of fish to light at set intervals during the night. We found a significant negative relationship between sleep disruption and the ability to learn a novel task. Specifically, we found that fish in the light‐disturbed sleep treatment took significantly longer and made more incorrect decisions to find a food reward, compared with the undisturbed sleep treatment. All fish were then allowed a normal sleep schedule and retested several days later to assess their ability to remember the task. In contrast to the learning phase, we observed no significant differences between the two treatment groups in remembering the food reward several days later. Our results demonstrate a negative impact of sleep disruption on performance in a cognitive challenging task that appeared to have the strongest effect when fish were first exposed to the challenge. Importantly, we show that the association between sleep and mental processes, such as learning, may be widespread across vertebrate taxa and potentially have an early origin in the evolutionary history of vertebrate animals.
O sono é vital para a saúde física e mental, desempenhando um papel crucial na consolidação da memória e na regulação emocional. Em estudantes universitários, a privação de sono pode afetar negativamente a memorização, a aprendizagem e o desempenho acadêmico. O estudo propõe revisar a literatura para compreender a relação entre a qualidade do sono e a capacidade de aprendizagem, visando desenvolver estratégias de intervenção para melhorar o ambiente acadêmico.
Insomnia after acquired brain injury (ABI) is common and can negatively impact an individual's rehabilitation, recovery, and quality of life. The present study investigated the feasibility and preliminary efficacy of a Brief Behavioural Treatment for Insomnia (BBTI) in a community sample following ABI. Ten participants were recruited. Seven participants attended four weekly sessions of BBTI and kept a daily sleep diary. Participants completed a semi-structured sleep interview at baseline and self-report measures of sleep, anxiety, and depression pre- and post-treatment as well as a treatment acceptability questionnaire post-treatment. Follow-up data were collected at 1-, 2-, and 3-months post-treatment. Visual analyses of the data were performed on a case-by-case basis. Five of the seven participants (71%) no longer met the criteria for insomnia disorder on the Sleep Condition Indicator (SCI) post-treatment. Treatment effects on sleep outcomes were either maintained or augmented at follow-ups. BBTI was found to be well tolerated, as evidenced by the high overall retention rates (70%) and positive feedback on the treatment acceptability questionnaire. These results provide preliminary evidence of BBTI being both feasible to use and potentially efficacious in individuals with post-brain-injury insomnia. Larger-scale randomised controlled trials are needed to establish the effectiveness of BBTI following ABI.
The development of the human brain is a dynamic and complex process, profoundly
influenced by the surrounding environment during childhood. Early life experiences and
educational enrichment play a crucial role in brain development, highlighting the interplay
between genetic and environmental factors (1). The field of econeurobiology provides an
essential framework for understanding how these factors interact to shape neurobiological development. This perspective is particularly significant in recognizing how education and health function as critical social determinants that influence cognitive and behavioral outcomes in children.
Memory consolidation strengthens new memories for stabilization, improvement, or permanency. Memory improves during practice breaks, but overnight sleep consolidation provides additional learning.
In the Acquisition Stage, a motor program forms during initial stable practice. Blocked practice, or massed practice, is required during this stage. The Stabilization Stage generally requires 4–6 hours post-practice to provide dependability and increased speed. Beginning in this stage, we should employ best-learning methods and variable practice. Enhancement, or overnight learning, depends on chemical processes that occur during sleep. We obtain modest gains in accuracy, speed, or both, and we gain more enhancement with the more difficult things we need to learn. After a brief review of research findings, I review how musicians can take advantage of distributed practice.
Infant sleep plays a crucial role in various aspects of language development, including the generalization of visual and auditory stimuli. The relative role of daytime naps and nocturnal sleep in these memory generalization processes is debated, with some studies observing significant generalization following a post-encoding nap and others observing it following nocturnal sleep, but only in cases where a post-encoding nap had occurred on the previous day. We conducted an online experiment with 8-month-old infants to determine whether a nap immediately following auditory exposure to words spoken by one talker enhances infants’ recognition of the same word forms produced by a different talker (i.e., word form generalization). This ability involves the extraction of constant auditory features from a pool of variable auditory instances and thus is an example of memory generalization. Results revealed a significant increase in word form generalization after a night’s sleep, specifically in infants who napped shortly after initial exposure to the words. This study provides the first evidence for the combined role of post-encoding naps and nocturnal sleep in phonological learning across different acoustic contexts. Phonological learning is frequently overlooked in research about word learning; however, prior to a child’s ability to associate words and their meanings and to use language referentially they must first encode and access the phonological forms of words and recognize them in running speech. Therefore, the findings from this study contribute significantly to our understanding of vocabulary acquisition by highlighting the importance of daytime naps in phonological learning.
Sleep is a physiological behaviour that occurs in all animal species forming about one-third of human life and is essential for survival. Prolonged sleep deprivation leads to severe physical impairment usually accompanied by cognitive loss and can even lead to death. S l e e p is a naturally recurring state of mind and body, characterized by relatively inhibited sensory activity and reduced interactions with surroundings, altered consciousness, reduced muscle activity and inhibition of nearly all voluntary eye muscles. Therefore, this study is aimed at investigating the impact of various sleep duration among students and the effect on their academic performance. Using a simple random method of sampling, questionnaires were physically distributed among medicine and surgery students of ESUT College of medicine and 265 students participated. Statistical analysis was done using the Statistical Package for the Social Sciences (SPSS) version 23 (SPSS Inc., Chicago, IL) with a value of <0.05 considered significant. From the analysis of the data retrieved from the questionnaire, it was observed that during a regular school week, majority of students (27.5%) obtained 6 hours of sleep, while the night prior to an examination, of students (27.9%) obtained 4 hours of sleep. Also, 68.7% of students believe that insufficient sleep has a negative impact on memory consolidation, while 31.3% believes otherwise. In conclusion from the results, the study suggests that students should be educated regarding good sleep hygiene practices as this has a positive effect on their academic performance.
The academic journey of a student is an important journey where each student is faced with a wide range of challenges, experiences, and transformations. Amidst all of this, students fall into a toxic cycle of sleep deprivation and increased stress levels. This chapter investigates the intricate relationship between stress and sleep patterns among college students, delving into the challenges posed by academic workload and the transition to a new environment. The authors explore the complex relationship between academic pressures, societal expectations, and the student's awareness of the long-term effects of sleep deprivation. Leveraging factors from the Pittsburgh sleep quality index (PSQI) and inquiring about stress-inducing scenarios, the authors curated a questionnaire that aims to uncover patterns of hidden mental illnesses. The methodology employs a data-centric pipeline, including encoding, normalization, and a derived index, to categorize individuals based on observed stress and sleep patterns, identifying potential mental health risks.
Entrepreneurship is a significant component in improving economic structure of a nation. In the recent years, a positive hike is visible in the number of women entrepreneurs throughout the world. According to the statistics, women entrepreneur's makes up approximately one-third of all global entrepreneurs. The rise of women entrepreneurship in the 21 st century benefits both women and the society. Although the importance of women entrepreneurship is accepted worldwide, there is a little attention in addressing their issues. Early screening of the mental health of women entrepreneurs helps them to encounter the stressors in their daily business. Therefore, this study throws light on efficacy of cognitive behaviour therapy in enhancing sleep quality and work-life balance of women entrepreneurs. Thirty seven participants were selected using random sampling method. The tools Pittsburgh Sleep Quality Index (PSQI) and Hayman's Work-life Balance (WLB) were used to collect the data. The results revealed that the cognitive behaviour therapy is effective in enhancing sleep quality and work-life balance among women entrepreneurs. The present study provides evidence that cognitive behaviour therapy helps in betterment of the lives of women entrepreneurs.
Stabilizing new memories requires coordinated neuronal spiking activity during sleep. Hippocampal sharp-wave ripples (SWRs) in the Cornu Ammonis (CA) region, and dentate spikes (DSs) in the dentate gyrus (DG) are prime candidate network events for supporting this offline process. SWRs have been studied extensively but the contribution of DSs remains unclear. By combining triple-(DG-CA3-CA1) ensemble recordings and closed-loop optogenetics in mice we show that, like SWRs, DSs synchronize spiking across DG and CA principal cells to reactivate population-level patterns of neuronal coactivity expressed during prior waking experience. Notably, the population coactivity structure in DSs is more diverse and higher-dimensional than that seen during SWRs. Importantly, suppressing DG granule cell spiking selectively during DSs impairs subsequent flexible memory performance during multi-object recognition tasks, and associated hippocampal patterns of neuronal coactivity. We conclude that DSs constitute a second offline network event central to hippocampal population dynamics serving memory-guided behavior.
Sleep is vital for physical and mental health, playing a crucial role in memory consolidation and emotional regulation. In college students, sleep deprivation can negatively affect memorization, learning, and academic performance. The study proposes to review the literature to understand the relationship between sleep quality and learning ability, aiming to develop intervention strategies to improve the academic environment.
This systematic review investigates the intricate relationship between visual memory consolidation and dreaming during the transition from Non-Rapid Eye Movement (NREM) to Rapid Eye Movement (REM) sleep in human subjects. Recognising the pivotal role of these sleep stages in memory processes and dreaming, we employed a comprehensive search strategy to identify relevant literature. A total of 23 studies were included in the quantitative synthesis, focusing on methodologies assessing visual memory and dreaming experiences during the NREM-REM transition. Each study underwent rigorous evaluation for risk of bias to ensure the reliability and validity of findings, with those identified as having a high risk of bias given less weight in result synthesis. Our analysis highlights the importance of understanding the interplay between visual memory consolidation and dreaming during the NREM-REM transition, shedding light on fundamental aspects of sleep-dependent memory processes and dreaming.
Sleep is vital for physical and mental health, playing a crucial role in memory consolidation and emotional regulation. In college students, sleep deprivation can negatively affect memorization, learning, and academic performance. The study proposes to review the literature to understand the relationship between sleep quality and learning capacity, aiming to develop intervention strategies to improve the academic environment
Insomnia after Acquired Brain Injury (ABI) is common and can negatively impact individuals’ rehabilitation, recovery and quality of life. The present study investigated the feasibility and preliminary efficacy of a Brief Behavioural Treatment for Insomnia (BBTI) in a community sample following ABI. Ten participants were recruited. Seven participants attended four weekly sessions of BBTI and kept a daily sleep diary. Participants completed a semi-structured sleep interview at baseline and self-report measures of sleep, anxiety and depression pre- and post-treatment as well as a treatment acceptability questionnaire post-treatment. Follow-up data were collected at one, two- and three-months post-treatment. Visual analyses of the data were performed on a case-by-case basis. Five participants (71%) demonstrated clinically significant improvements in sleep questionnaire measures, one showed treatment response and one (14%) showed nonresponse post-treatment. Treatment effects on sleep outcomes were either maintained or augmented at follow-ups. BBTI was found to be well-tolerable, as evidenced by high overall retention rates (70%) and positive feedback on the treatment acceptability questionnaire. These results provide preliminary evidence of BBTI being both feasible to use and efficacious in individuals with post-brain-injury insomnia. Larger-scale randomised controlled trials are needed to establish the effectiveness of BBTI following ABI.
Reviews the literature on REM sleep in regard to whether REM sleep prepares the S for subsequent learning or facilitates the retention of learning and/or the adaptation to prior stimulation. It is concluded that when studies are classified paradigmatically, E. M. Dewan's (1969) REM sleep metaprogramming hypothesis provides a useful conceptual scheme for interpreting the relevant literature. Suggested modifications to this hypothesis and anticipated future ones are discussed. (90 ref)
Proposes a ternary classificatory scheme of memory in which procedural, semantic, and episodic memory constitute a monohierarchical arrangement. In this scheme, episodic memory is a specialized subsystem of semantic memory, which in turn is a specialized subsystem of procedural memory. The 3 memory systems differ from one another in a number of ways, including the kind of consciousness that characterizes their operations. The ternary scheme overlaps with dichotomies and trichotomies of memory proposed by others. Evidence for multiple systems is reviewed, and illustrative data are provided from experiments. Direct priming effects were found to be both functionally and stochastically independent of recognition memory. (100 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
It has recently been reported that selective REM sleep deprivation (REMD) in college students results in memory impairment of the application of a set of rules in a logic task, but not recall of a paired associate task. The present experiments were designed to examine the effects of Total Sleep Deprivation (TSD) and (REMD) following acquisition of a pure motor task, the pursuit rotor. In Experiment 1, subjects (N = 90) were exposed to TSD for one of several nights following training. Results showed that TSD on the same night as training resulted in poorer performance on retest one week later. In Experiment 2, subjects (N = 42) were exposed to various kinds of sleep deprivation on the night of task acquisition. One group was subjected to REMD. Other groups included a non-REM awakening control group (NREMA), a TSD group, a normally rested Control group and a group allowed the first 4 h of sleep in the night before being subjected to TSD (LH - TSD) for the rest of the night. Results showed the REMD and Control groups to have excellent memory for this task while the TSD and LH - TSD subjects had significantly poorer memory for the task. The NREMA group showed a slight, but not significant deficit. It was concluded that Stage 2 sleep, rather than REM sleep was the important stage of sleep for efficient memory processing of the pursuit rotor task.
The function of rapid-eye-movement (REM) sleep is still unknown. One prevailing hypothesis suggests that REM sleep is important in processing memory traces. Here, using positron emission tomography (PET) and regional cerebral blood flow measurements, we show that waking experience influences regional brain activity during subsequent sleep. Several brain areas activated during the execution of a serial reaction time task during wakefulness were significantly more active during REM sleep in subjects previously trained on the task than in non-trained subjects. These results support the hypothesis that memory traces are processed during REM sleep in humans.
This article reviews recent studies of memory systems in humans and nonhuman primates. Three major conclusions from recent work are that (i) the capacity for nondeclarative (nonconscious) learning can now be studied in a broad array of tasks that assess classification learning, perceptuomotor skill learning, artificial grammar learning, and prototype abstraction; (ii) cortical areas adjacent to the hippocampal formation, including entorhinal, perirhinal, and parahippocampal cortices, are an essential part of the medial temporal lobe memory system that supports declarative (conscious) memory; and (iii) in humans, bilateral damage limited to the hippocampal formation is nevertheless sufficient to produce severe anterograde amnesia and temporally graded retrograde amnesia covering as much as 25 years.
In four consecutive weekly sessions 12 subjects, aged 20--25 years, listened to a sentence stimulus before the onset of sleep and were asked to reproduce it after an awakening provoked during stage 2 or REM sleep of the first cycle. Recall of the sentence stimuli heard before sleep was affected by their semantic acceptability, but was unaffected by the sleep type (REM/NREM) or by the length of waking preceding sleep. The differing retention intervals involved for the recall tests after REM and NREM sleep may, however, have masked any effect of the former on recall.
16 Ss were deprived of rapid eye movement (REM) sleep for 2 nights by awakening them at the first sign of each REM period. 16 control Ss, initially matched with REM-deprived Ss on a paired-associate learning task, were awakened a similar number of times, but only from sleep without REMs. There were no significant differences between REM-deprived and control Ss on post-deprivation recall of paired-associate adjectives learned prior to deprivation or on the post-deprivation serial learning of trigrams. The results fail to support an important role for REM sleep in human memory or learning. Neither did REM-deprived and control Ss differ significantly on two mood check lists or on a number cancellation performance test.
Rats had a memory loss of a fear response when they received an electroconvulsive shock 24 hours after the fear-conditioning
trial and preceded by a brief presentation of the conditioned stimulus. No such loss occurred when the conditioned stimulus
was not presented. The memory loss in animals given electroconvulsive shock 24 hours after conditioning was, furthermore,
as great as that displayed in animals given electroconvulsive shock immediately after conditioning. This result throws doubt
on the assertion that electroconvulsive shock exerts a selective amnesic effect on recently acquired memories and thus that
electroconvulsive shock produces amnesia solely through interference with memory trace consolidation.
Several paradigms of perceptual learning suggest that practice can trigger long-term, experience-dependent changes in the
adult visual system of humans. As shown here, performance of a basic visual discrimination task improved after a normal night's
sleep. Selective disruption of rapid eye movement (REM) sleep resulted in no performance gain during a comparable sleep interval,
although non-REM slow-wave sleep disruption did not affect improvement. On the other hand, deprivation of REM sleep had no
detrimental effects on the performance of a similar, but previously learned, task. These results indicate that a process of
human memory consolidation, active during sleep, is strongly dependent on REM sleep.
Learning a motor skill sets in motion neural processes that continue to evolve after practice has ended, a phenomenon known as consolidation. Here we present psychophysical evidence for this, and show that consolidation of a motor skill was disrupted when a second motor task was learned immediately after the first. There was no disruption if four hours elapsed between learning the two motor skills, with consolidation occurring gradually over this period. Previous studies in humans and other primates have found this time-dependent disruption of consolidation only in explicit memory tasks, which rely on brain structures in the medial temporal lobe. Our results indicate that motor memories, which do not depend on the medial temporal lobe, can be transformed by a similar process of consolidation. By extending the phenomenon of consolidation to motor memory, our results indicate that distinct neural systems share similar characteristics when encoding and storing new information.
A fundamental question about human memory is why some experiences are remembered whereas others are forgotten. Brain activation during word encoding was measured using blocked and event-related functional magnetic resonance imaging to examine how neural activation differs for subsequently remembered and subsequently forgotten experiences. Results revealed that the ability to later remember a verbal experience is predicted by the magnitude of activation in left prefrontal and temporal cortices during that experience. These findings provide direct evidence that left prefrontal and temporal regions jointly promote memory formation for verbalizable events.
Experiences are remembered or forgotten, but the neural determinants for the mnemonic fate of experience are unknown. Event-related
functional magnetic resonance imaging was used to identify specific brain activations that differentiated between visual experiences
that were later remembered well, remembered less well, or forgotten. During scanning of medial temporal lobe and frontal lobe
regions, subjects viewed complex, color photographs. Subjects later received a test of memory for the photographs. The magnitudes
of focal activations in right prefrontal cortex and in bilateral parahippocampal cortex predicted which photographs were later
remembered well, remembered less well, or forgotten.
The question of whether recognition memory judgments with and without recollection reflect dissociable patterns of brain activity is unresolved. We used event-related, functional magnetic resonance imaging (fMRI) of 12 healthy volunteers to measure hemodynamic responses associated with both studying and recognizing words. Volunteers made one of three judgments to each word during recognition: whether they recollected seeing it during study (R judgments), whether they experienced a feeling of familiarity in the absence of recollection (K judgments), or whether they did not remember seeing it during study (N judgments). Both R and K judgments for studied words were associated with enhanced responses in left prefrontal and left parietal cortices relative to N judgments for unstudied words. The opposite pattern was observed in bilateral temporoccipital regions and amygdalae. R judgments for studied words were associated with enhanced responses in anterior left prefrontal, left parietal, and posterior cingulate regions relative to K judgments. At study, a posterior left prefrontal region exhibited an enhanced response to words subsequently given R versus K judgments, but the response of this region during recognition did not differentiate R and K judgments. K judgments for studied words were associated with enhanced responses in right lateral and medial prefrontal cortex relative to both R judgments for studied words and N judgments for unstudied words, a difference we attribute to greater monitoring demands when memory judgments are less certain. These results suggest that the responses of different brain regions do dissociate according to the phenomenology associated with memory retrieval.
A memory trace in its active state is susceptible to interference by amnesic agents, such as hypothermia and electroconvulsive shock, and by NMDA receptor antagonists, suggesting that a time-dependent consolidation process occurs each time a memory is reactivated. The role of beta noradrenergic receptors in reconsolidation in rats was examined in both a positively reinforced radial maze task and a footshock-reinforced conditioned emotional response task. For the former, rats were trained over several days in a spatial reference memory task and received a single reactivation trial followed by propranolol. A temporally graded impairment was observed when propranolol treatment occurred after the memory reactivation trial. In the emotional task, memory impairing effects of propranolol were greater when the drug was administered after a reactivation trial than when administered immediately after the initial training. These results suggest that reactivation of memory triggers a beta receptor-dependent cascade of intracellular events, recapitulating that which occurs during initial postacquisition consolidation, thus permitting reorganization of the existing memory as a function of new information in the retrieval environment. This remarkable lability of an active memory trace provides a new basis for pharmacotherapeutic intervention in such syndromes as Posttraumatic Stress Disorder. beta adrenoreceptor antagonists may be promising pharmacological agents for attenuating debilitating memories at the time of their controlled reactivation.
The memory consolidation hypothesis proposed 100 years ago by Müller and Pilzecker continues to guide memory research. The
hypothesis that new memories consolidate slowly over time has stimulated studies revealing the hormonal and neural influences
regulating memory consolidation, as well as molecular and cellular mechanisms. This review examines the progress made over
the century in understanding the time-dependent processes that create our lasting memories.
The effects of sleep deprivation on the neural substrates of cognition are poorly understood. Here we used functional magnetic resonance imaging to measure the effects of 35 hours of sleep deprivation on cerebral activation during verbal learning in normal young volunteers. On the basis of a previous hypothesis, we predicted that the prefrontal cortex (PFC) would be less responsive to cognitive demands following sleep deprivation. Contrary to our expectations, however, the PFC was more responsive after one night of sleep deprivation than after normal sleep. Increased subjective sleepiness in sleep-deprived subjects correlated significantly with activation of the PFC. The temporal lobe was activated after normal sleep but not after sleep deprivation; in contrast, the parietal lobes were not activated after normal sleep but were activated after sleep deprivation. Although sleep deprivation significantly impaired free recall compared with the rested state, better free recall in sleep-deprived subjects was associated with greater parietal lobe activation. These findings show that there are dynamic, compensatory changes in cerebral activation during verbal learning after sleep deprivation and implicate the PFC and parietal lobes in this compensation.
The anterior prefrontal cortex is known to subserve higher cognitive functions such as task management and planning. Less is known, however, about the functional specialization of this cortical region in humans. Using functional MRI, we report a double dissociation: the medial anterior prefrontal cortex, in association with the ventral striatum, was engaged preferentially when subjects executed tasks in sequences that were expected, whereas the polar prefrontal cortex, in association with the dorsolateral striatum, was involved preferentially when subjects performed tasks in sequences that were contingent on unpredictable events. These results parallel the functional segregation previously described between the medial and lateral premotor cortex underlying planned and contingent motor control and extend this division to the anterior prefrontal cortex, when task management and planning are required. Thus, our findings support the assumption that common frontal organizational principles underlie motor and higher executive functions in humans.
WE measured regional cerebral blood flow (rCBF) with positron emission tomography to study changes in anatomical structures during the course of learning a complicated finger sequence of voluntary movements. Motor learning was accompanied by rCBF increases in the cerebellum, decreases in all limbic and paralimbic structures, and striatal decreases which changed to striatal increases as the motor skill was learned. Simultaneously, activations of initially contributing non-motor parts of the cerebral cortex vanished. Both cerebellar circuits and striatal circuits appear important for the storage of motor skills in the brain.
Behind every skilled movement lies months of practice. However, practice alone is not responsible for the acquisition of all skill; performance can improve between, not just within, practice sessions. An important principle shaping these offline improvements may be an individual's awareness of learning a new skill. New skills, such as a sequence of finger movements, can be learned unintentionally (with little awareness for the sequence, implicit learning) or intentionally (explicit learning). We measured skill in an implicit and explicit sequence-learning task before and after a 12 hr interval. This interval either did (8 p.m. to 8 a.m.) or did not (8 a.m. to 8 p.m.) include a period of sleep. Following explicit sequence learning, offline skill improvements were only observed when the 12 hr interval included sleep. This overnight improvement was correlated with the amount of NREM sleep. The same improvement could also be observed in the evening (with an interval from 8 p.m. to 8 p.m.), so it was not coupled to retesting at a particular time of day and cannot therefore be attributed to circadian factors. In contrast, in the implicit learning task, offline learning was observed regardless of whether the 12 hr interval did or did not contain a period of sleep. However, these improvements were not observed with only a 15 min interval between sessions. Therefore, the practice available within each session cannot account for these skill improvements. Instead, sufficient time is necessary for offline learning to occur. These results show a behavioral dissociation, based upon an individual's awareness for having learned a sequence of finger movements. Offline learning is sleep dependent for explicit skills but time dependent for implicit skills.
Recall of paired-associate lists (declarative memory) and mirror-tracing skills (procedural memory) was assessed after retention intervals defined over early and late nocturnal sleep. In addition, effects of sleep on recall were compared with those of early and late retention intervals filled with wakefulness. Twenty healthy men served as subjects. Saliva cortisol concentrations were determined before and after the retention intervals to determine pituitary-adrenal secretory activity. Sleep was determined somnopolygraphically. Sleep generally enhanced recall when compared with the effects of corresponding retention intervals of wakefulness. The benefit from sleep on recall depended on the phase of sleep and on the type of memory: Recall of paired-associate lists improved more during early sleep, and recall of mirror-tracing skills improved more during late sleep. The effects may reflect different influences of slow wave sleep (SWS) and rapid eye movement (REM) sleep since time in SWS was 5 times longer during the early than late sleep retention interval, and time in REM sleep was twice as long during late than early sleep (p < 0.005). Changes in cortisol concentrations, which independently of sleep and wakefulness were lower during early retention intervals than late ones, cannot account for the effects of sleep on memory. The experiments for the first time dissociate specific effects of early and late sleep on two principal types of memory, declarative and procedural, in humans.
Interest in the ability to learn and use sequences for pro-cessing information and actions is by no means a recent phenomenon 1 . Following the seminal study of Nissen and Bullemer 2 , there has been an explosion of interest in se-quence learning. While there are a variety of motivations for experimentation in sequence learning; and in particular the use of the serial reaction-time task (SRT) (see Box 1), three main reasons characterize much of this interest: (1) Sequencing of information and actions is a funda-mental human ability We use sequences of information or sequences of actions in a variety of everyday tasks: from sequencing sounds in speech, to sequencing movements in typing or playing instruments, to sequencing actions in driving an automobile. (2) Sequence learning is an easily studied example of skill acquisition SRT learning is comparatively simple to implement and manipulate, and improvement occurs over a relatively short time. Reaction times and error rates readily and objectively assess improvement. Sequence learning has been studied in diverse populations, from neuropsychological patients to infants 3 . Further, the potential exists to study sequence learning in animals. (3) Sequence learning may be a complex form of implicit learning If sequence learning is accepted as sometimes occurring without awareness (see below), then it provides an in-triguing example of nonconscious learning of a complex cognitive task. With the development of a simple paradigm for study-ing skill acquisition, it is hardly surprising that sequence learning has become a productive domain. However, vari-ations in methodology make comparisons between studies difficult. For example, simple parametric manipulations such as varying the response-to-stimulus interval (RSI) can influence the amount of learning 4 . Initially we will address separately the major questions that the field has revolved around. Ultimately we attempt to point out how an integrated approach (combining empirical analysis, cognitive theory and other converging evidence) is necessary to resolve some of the discrepancies in the literature. Representation of sequences What is being represented in sequence learning? One fundamental question concerns the very nature of the sequential representation. When we learn sequences, what type of information is actually being learned? The SRT par-adigm normally involves both sequences of stimuli as well as the corresponding sequences of responses. The benefits in reaction time and error rate may be associated with the sequencing of stimuli, the sequencing of responses, or the sequencing of intermediate representations. One method used to address what information is being represented is to employ a transfer of learning paradigm. Cohen et al. 5 , for example, examined the transfer of sequence knowledge following changes in the response. Transfer of previous learning was observed when responding changed from using three fingers to a single finger and correspond-ing arm movements. The representation of the sequence cannot therefore be tied to any particular effector, which echoes the results of effector-independent production of sequences required for writing 6 . Furthermore, Keele et al. 7 showed that in a more extreme type of response manipu-lation (from manual to verbal) transfer still occurs, but was now incomplete. This data suggest that sequence learning cannot be entirely stimulus-based as some learning is lost in the change from manual to verbal responses despite stimulus information remaining constant. It also suggests the learn-ing is not entirely response-based since some transfer does occur over extreme response changes. The results, however, do not rule out the possibility that manual and verbal responses share some common, very abstract representation.
Studied the effect of an all-day, 3-wk intensive language course in French on the undisturbed sleep of a 25-yr-old male S of above average intelligence and memory performance. The study attempted to obtain further information about the different aspects of sleep and the relation between learning and memory processes. In most of the numerous theories about the memory function of sleep, it is postulated that REM sleep fulfills a memory-promoting function. The tonic aspect of REM sleep was the 1st sleep variable analyzed in this study. With a meaningful learning task, such as learning a foreign language, it is possible to achieve a high degree of learning motivation. Undesirable side effects from emotional disturbances which might compete with the learning and memory processes in their influences on sleep were not present. The S was able to accustom himself to sleeping under laboratory conditions during 5 adaptation nights. 45 consecutive nights—14 preexperimental baseline, 19 experimental, and 12 postexperimental baseline nights—were recorded. In both baseline phases, the S was able to arrange his days as desired but was requested not to undertake any physically or mentally strenuous activity. The percentage of REM sleep during the learning phase showed no significant variation from the baseline phases. The only REM sleep parameter that varied significantly was the latency of the 3rd REM sleep phase. It was, in relation to the time of falling asleep, shortened by about 30 min during the learning phase as opposed to the baseline phases (significant at the 5% level). (71 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Until recently the most striking changes observed during experimental studies of sleep deprivation have been subjective ones. Performance variables have not been consistently sensitive to sleep loss. More than 60 years after the first laboratory study, in 1896,10 a recent review concluded that “subjective attitude (appearance, mood, and behavior) is the only factor severely affected by sleep reduction.”5
Studies by the Walter Reed group3,11,14 and by Wilkinson13 and others indicate, however, that certain aspects of performance can be identified which are sensitive to sleep loss. In particular, tasks which require sustained attention show marked decrement as sleep loss increases.
The most frequent changes reported in earlier studies were increased restlessness, apathy, irritability, inability to concentrate, visual illusions, and hallucinations. At least two investigators6,12 reported extreme confusion and delusions of persecution. Recently, Bliss and his colleagues1 conducted
We have previously shown that several brain areas are activated both during sequence learning at wake and during subsequent rapid-eye-movements (REM) sleep (Nat. Neurosci. 3 (2000) 831–836), suggesting that REM sleep participates in the reprocessing of recent memory traces in humans. However, the nature of the reprocessed information remains open. Here, we show that regional cerebral reactivation during posttraining REM sleep is not merely related to the acquisition of basic visuomotor skills during prior practice of the serial reaction time task, but rather to the implicit acquisition of the probabilistic rules that defined stimulus sequences. Moreover, functional connections between the reactivated cuneus and the striatum—the latter being critical for implicit sequence learning—are reinforced during REM sleep after practice on a probabilistic rather than on a random sequence of stimuli. Our results therefore support the hypothesis that REM sleep is deeply involved in the reprocessing and optimization of the high-order information contained in the material to be learned. In addition, we show that the level of acquisition of probabilistic rules attained prior to sleep is correlated to the increase in regional cerebral blood flow during subsequent REM sleep. This suggests that posttraining cerebral reactivation is modulated by the strength of the memory traces developed during the learning episode. Our data provide the first experimental evidence for a link between behavioral performance and cerebral reactivation during REM sleep.
We analysed coccolithophorid and calcareous dinoflagellate assemblages from an 18-month (June 1990–August 1991) sediment trap record in the Bay of Biscay. With three trap deployments, the sampling resolution ranged from five to eight days. Characterisation of the assemblage dynamics is based on the use of statistical tools such as principal component analysis (PCA). The assemblages record seasonal and short-term events, implying that despite the dominance of lateral transport from the shelf, the traps faithfully record ecological dynamics. Summer species are Braarudosphaera bigelowii, Calcidiscus leptoporus (small), Coccolithus pelagicus, Emiliania huxleyi (closed), small Gephyrocapsa, Helicosphaera carteri, Pontosphaera japonica, Syracosphaera gr. molischii, Thoracosphaera heimii, Umbellosphaera tenuis. Autumn assemblages are characterised by the high frequency of C. leptoporus (large), Syracosphaera pulchra, Florisphaera profunda and E. huxleyi (open). Pontosphaera discopora and G. muellerae are most abundant during the winter whereas Umbilicosphaera sibogae peaks during spring. No other species shows a clear seasonal abundance pattern. The changes in assemblage composition are correlatable with changes in environmental parameters, such as wind, wave and light. Environmental dynamics, linked to seasonal succession, trigger a shift in relative abundance of morphotypes of E. huxleyi and C. leptoporus. The relations between species in the coccolithophorid community are characterised by a strong species dominance: (1) E. huxleyi dominated the assemblages (54–94%) and (2) the community followed a geometric distribution (in ranked dominance of species). The dominance increases during higher phytoplankton production as indicated by higher fluxes of diatoms, silicoflagellates and coccospheres of E. huxleyi.
Based on the assumption that the mental aspect of REM sleep is an extreme state of divergent thinking, it was hypothesized that the psychological effect of REM deprivation varies on a dimension of creativity versus rote learning. On the creativity pole, REM deprivation has a damaging effect, while on the rote learning pole, it has a beneficial effect.
The subjects (.Ss) were 12 male undergraduate students. Each spent 3 nights in the laboratory. Ss served us their own controls, with 5 days separating the REM deprivation and the non‐REM deprivation nights.
Before going to bed, each of the Ss was given 4 tasks, on which testing took place the fallowing morning. Comparable tasks, in a balanced design, were used on the REM deprivation and on the non‐REM deprivation nights, The tasks given were: (a) serial memory, (b) “clustering” memory, (c) word fluency, and (d) Guilford's Utility Test.
Results showed a significant decrement in creativity (the Guilford's Utility Test), and a significant increment in role memory (the serial memory task), due to REM deprivation. No significant differences were found for the other 2 tasks used, which were somewhere in‐between the two extreme poles of creativity and role learning. These results might explain earlier, contradictory findings in this area.
These results lend further support to the general assumption that REM sleep is used by the organism for internal information processing. However, an additional assumption has to be. made, that this processing is divergent and not convergent.
Reviews the literature on REM sleep in regard to whether REM sleep prepares the S for subsequent learning or facilitates the retention of learning and/or the adaptation to prior stimulation. It is concluded that when studies are classified paradigmatically, E. M. Dewan's (1969) REM sleep metaprogramming hypothesis provides a useful conceptual scheme for interpreting the relevant literature. Suggested modifications to this hypothesis and anticipated future ones are discussed. (90 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
An observation first made in our laboratory was responsible for focusing our attention upon an apparent increase in REM sleep in relation to altered visual experiences during the day. This finding was consistent with certain information-processing theories of REM sleep function and seemed to offer experimental support for them. Therefore, we proceeded to conduct a series of closely related experiments, designed to investigate further the possible REM-augmenting effects of spatially rearranged vision. Although our first two experiments seemed to support the original observation, subsequent, more carefully designed experiments, did not. The combined results from all of our experiments forced us to conclude that there is no consistent effect of distorted daytime vision on the amount or percentage of REM sleep. REM latency, or the number of rapid eye movements during REM periods. We suggest that future research on the topic employ experiments specifically designed to explore relationships between personality variables and a subject's REM sleep response to altered sensory input.
One proposal referring to a specific function of REM sleep has been that it is necessary for, or at least conductive to, the progress of memory consolidation. This hypothesis was tested by comparing the effects on story retention of REM deprivation against an S4 deprived control. It was found that recall accuracy following REM deprivation was significantly poorer than following S4 deprivation. Furthermore, the degree of deterioration in recall accuracy during REM recovery sleep was less than during S4 recovery sleep. These findings were interpreted as evidence for active REM facilitation of memory consolidation. However, alternative explanations based upon proactive influences need to be investigated.
We measured regional cerebral blood flow (rCBF) with positron emission tomography to study changes in anatomical structures during the course of learning a complicated finger sequence of voluntary movements. Motor learning was accompanied by rCBF increases in the cerebellum, decreases in all limbic and paralimbic structures, and striatal decreases which changed to striatal increases as the motor skill was learned. Simultaneously, activations of initially contributing non-motor parts of the cerebral cortex vanished. Both cerebellar circuits and striatal circuits appear important for the storage of motor skills in the brain.
Ten anglophone students taking a 6-week French immersion course were recorded in the sleep laboratory during 4 consecutive nights before the course, during the course and after the course. There was a positive and significant (P less than 0.05) correlation between language learning efficiency and increases in the percentage of rapid eye movement (REM) sleep from pre-course to course periods. This observation suggests that learning performance may be an important factor in the relationship between information processing and REM sleep.
Animal studies are examined in relation to the sleep-learning hypothesis. It is concluded that the data best support the idea of special periods of paradoxical sleep (PS) within the 24 hour period which are specifically involved with the learning process. The onset and duration of these PS "windows" varies with strain of animal, type of task and number of training trials per session. Alternative explanations and theories are considered.
SOME theorists have ignored the content of dreams and concentrated
specifically on chemical or physiological aspects1.
Oswald2 has postulated that rapid eye movement
(REM)3 sleep is a non-specific indication of many forms of
synthesis within cerebral neurones, and that periods of massive learning
would cause high percentages of REM sleep. Others have explained both
dream content and REM state as playing a part in information processing.
Some have used computer analogies, suggesting that reorganization takes
place during the REM state, involving revision arid updating of
cognitive processes and memories4. It is known that
remembering involves distortion and conventionalization5, so
REM-induced reorganization should also show ``effort after meaning''.
Rats were deprived of rapid eye movement (REM) sleep for up to five days by confinement to a small platform surrounded by water. Acquisition of three tasks—passive avoidance, active avoidance, and an appetitive alternation discrimination—was slower following REM sleep deprivation than after normal (home cage) or stress control (immersed in cold water) treatments. Sleep loss controls, who had reduced non-REM sleep, performed as well as normals and better than the REM sleep deprived rats on the two shock avoidance tasks—the alternation test was not employed. Thus, five days of REM sleep deprivation in the rat produced marked acquisition deficits which were not task specific and which did not appear to be due to nonspecific stress, non-REM sleep loss, or changes in activity levels.
When rats received a brief footshock upon stepping off an elevated platform, and an electroconvulsive shock 30 seconds or 6 hours afterward, amnesia was not observed 24 hours later. If a second footshock (noncontingent) was delivered 0.5 second before the electroconvulsive shock, amnesia was observed. The amnesia was temporary if conditioning was strong and permanent if conditioning was weak.
We propose that the function of dream sleep (more properly rapid-eye movement or REM sleep) is to remove certain undesirable modes of interaction in networks of cells in the cerebral cortex. We postulate that this is done in REM sleep by a reverse learning mechanism (see also p. 158), so that the trace in the brain of the unconscious dream is weakened, rather than strengthened, by the dream.
Multiple visual areas in the cortex of nonhuman primates are organized into two hierarchically organized and functionally specialized processing pathways, a 'ventral stream' for object vision and a 'dorsal stream' for spatial vision. Recent findings from positron emission tomography activation studies have localized these pathways within the human brain, yielding insights into cortical hierarchies, specialization of function, and attentional mechanisms.
In order to study whether paradoxical sleep (PS) is necessary to prepare subjects for the subsequent learning of a distributed two-way active avoidance conditioning, 10 rats were subjected to 5 h of paradoxical sleep deprivation (PSD group) by means of the platform method immediately before each of 5 acquisition sessions (one daily), as well as before a long-term retention (LTR) session (14 days). Another group of rats (PSD control group; n = 10) were placed on large platforms as a control for the side effects induced by PSD platforms. Rats in the dry control group (n = 10) did not receive any treatment. The number of avoidances of the PSD group was significantly lower on the 1st, 2nd and 3rd acquisition sessions compared to the PSD control group, and on the 2nd and 3rd sessions compared to the dry control group. PSD rats made significantly less intertrial crossings than dry controls on the 2nd and 3rd acquisition sessions, but no significant correlations were found between this variable and the number of avoidances. Therefore, our results are not fully in contradiction with the hypothesis that PS previous to the training sessions might prepare the animal for subsequent learning, although the influence of locomotor changes upon the performance of PSD subjects cannot be fully rejected.
There is a discrepancy between the results of imaging studies in which subjects learn motor sequences. Some experiments have shown decreases in the activation of some areas as learning increased, whereas others have reported learning-related increases as learning progressed. We have exploited fMRI to measure changes in blood oxygen leve-dependent (BOLD) signal throughout the course of learning. T2*-weighted echo-planar images were acquired over the whole brain for 40 min while the subjects learned a sequence eight moves long by trial and error. The movements were visually paced every 3.2 s and visual feedback was provided to the subjects. A baseline period followed each activation period. The effect due to the experimental conditions was modeled using a square-wave function, time locked to their occurrence. Changes over time in the difference between activation and baseline signal were modeled using a set of polynomial basis functions. This allowed us to take into account linear as well as nonlinear changes over time. Low-frequency changes over time common to both activation and baseline conditions (and thus not learning related) were modeled and removed. Linear and nonlinear changes of BOLD signal over time were found in prefrontal, premotor, and parietal cortex and in neostriatal and cerebellar areas. Single-unit recordings in nonhuman primates during the learning of motor tasks have clearly shown increased activity early in learning, followed by a decrease as learning progressed. Both phenomena can be observed at the population level in the present study.
The notion that dreaming might alter the strength of associative links in memory was first proposed almost 200 years ago. But no strong evidence of such altered associative links has been obtained. Semantic priming can be used to quantify the strength of associative links between pairs of words; it is thought to measure the automatic spread of activation from a “node” representing one word to nodes representing semantically related words. Semantic priming could thus be used to test for global alterations in the strengths of associative links across the wake-sleep cycle.
Awakenings from REM and nonREM (NREM) sleep produce a period of state carry-over during which performance is altered as a result of the brain's slow transition to full wakefulness, and cognitive testing in this period can provide information about the functioning of the brain during the prior sleep period. When subjects were tested across the night—before and after a night's sleep as well as immediately following forced awakenings from REM and NREM sleep—weak priming (e.g., thief-wrong) was found to be state dependent (p = 0.016), whereas strong priming (e.g., hot-cold) was not (p = 0.89). Weak primes were most effective in the presleep and REM sleep conditions and least effective in NREM and postsleep conditions.
Most striking are analyses comparing weak and strong priming within each wake-sleep state. Contrary to the normal pattern of priming, subjects awakened from REM sleep showed greater priming by weak primes than by strong primes (p = 0.01). This result was seen in each of three protocols. In contrast, strong priming exceeded weak priming in NREM sleep.
The shift in weak priming seen after REM sleep awakenings suggests that cognition during REM sleep is qualitatively different from that of waking and NREM sleep and may reflect a shift in associative memory systems, a shift that we hypothesize underlies the bizarre and hyperassociative character of REM-sleep dreaming. Known changes in brainstem activity that control the transition into and maintenance of REM sleep provide a possible explanation of this shift.
Historical evidence suggests that sleep deprivation affects temporal memory, but this has not been studied systematically. We explored the effects of 36 hr of sleep deprivation on a neuropsychological test of temporal memory. To promote optimal performance, the test was short, novel, and interesting, and caffeine was used to reduce "sleepiness". A total of 40 young adults were randomized into four groups: control + caffeine (Cc), control + placebo (Cp), sleep deprived + caffeine (SDc), and sleep deprived + placebo (SDp). Controls slept normally. Caffeine (350 mg) or placebo were given just prior to testing. The task comprised colour photographs of unknown faces and had two components: recognition memory (distinction between previously presented and novel faces), and recency discrimination (temporal memory), when a previously shown face was presented. An interpolated task, self-ordered pointing, acted as a distraction. Caffeine had no effects within control conditions, but significantly reduced subjective sleepiness in SDc. Recognition was unaffected by sleep deprivation, whereas for recency, sleep deprivation groups scored significantly lower than controls. There was no significant improvement of recency with caffeine in the SDc group. Both sleep deprivation groups had poorer insight into their performance with recency. Self-ordered pointing remained unchanged. In conclusion, sleep deprivation impairs temporal memory (i.e. recency) despite other conditions promoting optimal performance.
Performance on a visual discrimination task shows long-term improvement after a single training session. When tested within 24 hr of training, improvement was not observed unless subjects obtained at least 6 hr of posttraining sleep prior to retesting, in which case improvement was proportional to the amount of sleep in excess of 6 hr. For subjects averaging 8 hr of sleep, overnight improvement was proportional to the amount of slow wave sleep (SWS) in the first quarter of the night, as well as the amount of rapid eye movement sleep (REM) in the last quarter. REM during the intervening 4 hr did not appear to contribute to improvement. A two-step process, modeling throughput as the product of the amount of early SWS and late REM, accounts for 80 percent of intersubject variance. These results suggest that, in the case of this visual discrimination task, both SWS and REM are required to consolidate experience-dependent neuronal changes into a form that supports improved task performance.
Previous studies have shown a decrease in rapid eye movement (REM) frequency during desynchronized sleep in recovery nights following total or partial sleep deprivation. This effect has been ascribed to an increase in sleep need or sleep depth consequent to sleep length manipulations. The aims of this study were to assess REM frequency variations in the recovery night after two consecutive nights of selective slow-wave sleep (SWS) deprivation, and to evaluate the relationships between REM frequency and SWS amount and auditory arousal thresholds (AAT), as an independent index of sleep depth. Ten normal males slept for six consecutive nights in the laboratory: one adaptation, two baseline, two selective SWS deprivation and one recovery night. SWS deprivation allowed us to set the SWS amount during both deprivation nights close to zero, without any shortening of total sleep time. In the ensuing recovery night a significant SWS rebound was found, accompanied by an increase in AAT. In addition, REM frequency decreased significantly compared with baseline. This effect cannot be attributed to a variation in prior sleep duration, since there was no sleep loss during the selective SWS deprivation nights. Stepwise regression also showed that the decrease in REM frequency is not correlated with the increase in AAT, the traditional index of sleep depth, but is correlated with SWS rebound.
Twelve rats were deprived of paradoxical sleep (PS) for eight hours using the small platform method. PS-deprived and control rats then learned either the standard allocentric version (using external cues) of the Morris Water Maze (MWM) or a delayed alternation version (changing the platform location between trials: MWM(DA)). Overall, rats learning the MWM(DA) made more quadrant entries than rats learning the allocentric version. Compared to other rats, PS-deprived rats crossed more quadrants only in the MWM(DA). These results show that MWM(DA) is a more complex task to learn and is more vulnerable to PS deprivation than allocentric spatial orientation. Since delayed alternation is dependent upon frontal structures, we propose that tasks involving the frontal cortex are more sensitive to short-term PS deprivation than tasks related to hippocampal structures.