The rhythm of rest and excess

The Ecology of Human Sleep (EcoSleep) Cohort Study: Protocol for a longitudinal repeated measurement burst design study to assess the relationship between sleep determinants and outcomes under real-world conditions across time of year

The interplay of daily life factors, including mood, physical activity, or light exposure, influences sleep architecture and quality. Laboratory-based studies often isolate these determinants to establish causality, thereby sacrificing ecological validity. Furthermore, little is known about time-of-year changes in sleep and circadian-related variables at high resolution, including the magnitude of individual change across time of year under real-world conditions. The Ecology of Human Sleep (EcoSleep) cohort study will investigate the combined impact of sleep determinants on individuals' daily sleep episodes to elucidate which waking events modify sleep patterns. A second goal is to describe high-resolution individual sleep and circadian-related changes across the year to understand intra- and inter-individual variability. This study is a prospective cohort study with a measurement-burst design. Healthy adults aged 18-35 years (N = 12) will be enrolled for 12 months. Participants will continuously wear actimeters and pendant-attached light loggers. A subgroup will also measure interstitial fluid glucose levels (six paticipants). Every 4 weeks, all participants will undergo three consecutive measurement days of four ecological momentary assessments each day ('bursts') to sample sleep determinants during wake. Participants will also continuously wear temperature loggers (iButtons) during the bursts. Body weight will be captured before and after the bursts in the laboratory. The bursts will be separated by two at-home electroencephalogram recordings each night. Circadian phase and amplitude will be estimated during the bursts from hair follicles, and habitual melatonin onset will be derived through saliva sampling. Environmental parameters (bedroom temperature, humidity, and air pressure) will be recorded continuously.

Sleep and mood in central serous chorioretinopathy

PURPOSE

To investigate the impact of central serous chorioretinopathy on sleep and mood in patients with acute and chronic central serous chorioretinopathy.

METHODS

This cross-sectional study compared sleep and mood differences between central serous chorioretinopathy and control patients recruited from Ophthalmology clinics at the John Radcliffe Hospital, Oxford between 2012 and 2020. Data including visual acuity, type of central serous chorioretinopathy (acute or chronic; aCSC/cCSC), sex, and chronotype were obtained. Sleep quality was measured using the Pittsburgh Sleep Quality Index (PSQI); the Hospital Anxiety and Depression Scale (HADS) was used to evaluate anxiety (HADS-A) and depression (HADS-D).

RESULTS

A total of 247 age matched controls and 109 patients with central serous chorioretinopathy participated. There were no significant differences in PSQI or HADs (P > 0.05) between the two groups. Females exhibited significantly higher PSQI scores than males both for control and central serous chorioretinopathy groups (P < 0.05). Within the central serous chorioretinopathy group, 88 (81%) had chronic central serous chorioretinopathy and 21 (19%) had acute central serous chorioretinopathy, and an increase in daytime dysfunction was seen in the acute phenotype compared to chronic (P = 0.018).

CONCLUSION

In our study, no significant differences in sleep quality or mood scores were identified in central serous chorioretinopathy patients, when compared to controls. Worsened sleep for females was present when compared to males, both in central serous chorioretinopathy and control groups. Within central serous chorioretinopathy groups, worsened daytime function was observed in acute versus chronic - a larger study would help distinguish the effect of chronicity on sleep.

Time-of-day effects on physical performance and perceptual responses in Brazilian Jiu-Jitsu athletes

This study investigated how the time of day affects physical performance and perceptual responses in Brazilian Jiu-Jitsu (BJJ) athletes. Given the significance of circadian rhythms on athletic capabilities, we aimed to determine whether performance variations occur across different times of the day (morning, 10:00-11:00h; afternoon, 14:00-15:00h; and evening, 18:00-19:00h) and if these effects differ by sex. In total, 23 BJJ athletes (9 females, 14 males) participated in this study. The athletes performed physical tests including the maximal isometric handgrip strength test (HGS), Kimono Grip Strength Endurance Test (KGST), and a BJJ-specific test (BJJST) in the morning, afternoon, and evening. Perceptual responses (RPE) were also collected before the BJJST. Results showed enhanced physical performance in the evening for most tests, including increased HGS and superior performance in the KGST and BJJST for both sexes (p < 0.05). No significant differences were observed in perceptual responses (RPE) or between sexes (p > 0.05). We conclude that BJJ athletes generally perform better in the evening compared to other times of the day, with notable improvements in HSG and specific BJJ tests. The study highlights the importance of aligning training schedules with an athlete's circadian rhythm to optimize performance, leading to more efficient training sessions and improved long-term performance outcomes.

Architecture, light, and circadian biology: A scoping review

Light-dark (LD) can support or challenge the circadian organization of physiology and health. As an indoor species, the built environment inevitably influences the patterns and intensities of our LD exposures, thereby affecting health. We reviewed to what extent architectural features have been studied alongside LD and circadian biology. Systematic screening of literature from thirty-one databases identified n = 11 relevant human- and n = 19 relevant field- and simulation- studies; the latter included exploration of LD and architectural details with pertinent reference to circadian biology. Charting and synthesis concerned architecture, LD sources and metrics, circadian biology-related parameters, and health more generally. Human studies that investigate architecture, LD, and circadian biology together are limited by few participants, few architectural features, and few measurements. Most emphasis is on window-related aspects but must be judged as first explorations (i.e., not suitable to compare e.g., glazing vs shading vs position). Novel findings include the potential for time-specific alteration of blue light transmittance through windows. Circadian-light metrics (e.g., the Circadian Stimulus) are in use but analyses of links between architecture and circadian-light metrics together with biology are lacking. In conclusion, first empirical evidence links elements of LD, architecture, and circadian biology. Novel and necessary avenues of research are discussed.

Influence of extreme light/dark cycles on monoamine levels, physiological indices, and emotional behaviors in rats

Aberrant light/dark (LD) cycles are prevalent in modern society due to electric light usage, leading to mood disorders from circadian disruption or misalignment. However, research on the physiological and behavioral effects of LD variations on brain neurotransmitters is limited. We investigated the effects of extreme LD cycles on body weight (BW), core body temperature (Tcore), locomotor activity (ACT), emotional behaviors, and monoamine levels (noradrenaline [NA], dopamine [DA], and serotonin [5-HT]) in male Wistar rats that were exposed to 1 month of either long light phase (20 L:4D), long dark phase (4 L:20D), or normal (12 L:12D) LD cycles. The 20 L:4D rats exhibited blunted rhythms, with decreased amplitude and advanced/delayed acrophase in Tcore and ACT, alongside increased BW. The 4 L:20D rats showed circadian misalignment, with increased/decreased amplitude in Tcore or ACT and delayed acrophase in Tcore and ACT, also gaining BW. In the 20 L:4D group, NA and 5-HT levels decreased in the suprachiasmatic nucleus and amygdala, respectively, while the 4 L:20D group had increased DA and 5-HT levels in the caudate putamen and dorsomedial hypothalamus, respectively. Open field and social interaction tests indicated anxiety-like behaviors in both test groups. Overall, each extreme LD cycle affected Tcore, ACT amplitude, acrophase, and monoamine levels differently, inducing anxiogenic responses.

An Accurate and Efficient Approach to Knowledge Extraction from Scientific Publications Using Structured Ontology Models, Graph Neural Networks, and Large Language Models

The rapid growth of biomedical literature makes it challenging for researchers to stay current. Integrating knowledge from various sources is crucial for studying complex biological systems. Traditional text-mining methods often have limited accuracy because they don't capture semantic and contextual nuances. Deep-learning models can be computationally expensive and typically have low interpretability, though efforts in explainable AI aim to mitigate this. Furthermore, transformer-based models have a tendency to produce false or made-up information-a problem known as hallucination-which is especially prevalent in large language models (LLMs). This study proposes a hybrid approach combining text-mining techniques with graph neural networks (GNNs) and fine-tuned large language models (LLMs) to extend biomedical knowledge graphs and interpret predicted edges based on published literature. An LLM is used to validate predictions and provide explanations. Evaluated on a corpus of experimentally confirmed protein interactions, the approach achieved a Matthews correlation coefficient (MCC) of 0.772. Applied to insomnia, the approach identified 25 interactions between 32 human proteins absent in known knowledge bases, including regulatory interactions between MAOA and 5-HT2C, binding between ADAM22 and 14-3-3 proteins, which is implicated in neurological diseases, and a circadian regulatory loop involving RORB and NR1D1. The hybrid GNN-LLM method analyzes biomedical literature efficiency to uncover potential molecular interactions for complex disorders. It can accelerate therapeutic target discovery by focusing expert verification on the most relevant automatically extracted information.

Disrupted Circadian Rhythms and Substance Use Disorders: A Narrative Review

Substance use disorder is a major global health concern, with a high prevalence among adolescents and young adults. The most common substances of abuse include alcohol, marijuana, cocaine, nicotine, and opiates. Evidence suggests that a mismatch between contemporary lifestyle and environmental demands leads to disrupted circadian rhythms that impair optimal physiological and behavioral function, which can increase the vulnerability to develop substance use disorder and related problems. The circadian system plays an important role in regulating the sleep-wake cycle and reward processing, both of which directly affect substance abuse. Distorted substance use can have a reciprocal effect on the circadian system by influencing circadian clock gene expression. Considering the detrimental health consequences and profound societal impact of substance use disorder, it is crucial to comprehend its complex association with circadian rhythms, which can pave the way for the generation of novel chronotherapeutic treatment approaches. In this narrative review, we have explored the potential contributions of disrupted circadian rhythms and sleep on use and relapse of different substances of abuse. The involvement of circadian clock genes with drug reward pathways is discussed, along with the potential research areas that can be explored to minimize disordered substance use by improving circadian hygiene.

Peripheral inflammation as a potential mechanism and preventive strategy for perioperative neurocognitive disorder under general anesthesia and surgery

General anesthesia, as a commonly used medical intervention, has been widely applied during surgical procedures to ensure rapid loss of consciousness and pain relief for patients. However, recent research suggests that general anesthesia may be associated with the occurrence of perioperative neurocognitive disorder (PND). PND is characterized by a decline in cognitive function after surgery, including impairments in attention, memory, learning, and executive functions. With the increasing trend of population aging, the burden of PND on patients and society's health and economy is becoming more evident. Currently, the clinical consensus tends to believe that peripheral inflammation is involved in the pathogenesis of PND, providing strong support for further investigating the mechanisms and prevention of PND.

Psychological endurance: how grit, resilience, and related factors contribute to sustained effort despite adversity

Many concepts describe how individuals sustain effort despite challenging circumstances. For example, scholars and practitioners may incorporate discussions of grit, hardiness, self-control, and resilience into their ideas of performance under adversity. Although there are nuanced points underlying each construct capable of generating empirically sound propositions, the shared attributes make them difficult to differentiate. As a result, substantial confusion arises when debating how these related factors concomitantly contribute to success, especially when practitioners attempt to communicate these ideas in applied settings. The model proposed here-psychological endurance-is a unified theory to explore how multiple concepts contribute to sustained goal-directed behaviors and individual success. Central to this model is the metaphor of a psychological battery, which potentiates and sustains optimal performance despite adversity. Grit and hardiness are associated with the maximum charge of the psychological battery, or how long an individual could sustain effort. Self-control modulates energy management that augments effort required to sustain endurance, whereas resilience represents the ability to recharge. These factors are constrained by both psychological and physiological stressors in the environment that drain the psychology battery. Taken together, these ideas form a novel framework to discuss related psychological concepts, and ideally, optimize intervention to enhance psychological endurance.

Promoting adolescent sleep and circadian function: A narrative review on the importance of daylight access in schools

Adolescent sleep disturbances and circadian delays pose significant challenges to mood and daytime functioning. In this narrative review, we explore the impact of light on sleep and highlight the importance of monitoring and managing light exposure in adolescents throughout the day and night. The benefits of daylight exposure in mitigating sleep and circadian disruptions are well-established; however, interventions targeting access to daylight in adolescents remain understudied and underutilized. The primary aim of this narrative review is to bring attention to this gap in the literature and propose the need for institutional-level interventions that promote access to daylight, especially considering adolescents' early school start times and substantial time spent indoors on weekdays. School-led interventions, such as active commuting to school and outdoor curriculums, have promising effects on sleep and circadian rhythms. Additionally, practical measures to optimize natural light in classrooms, including managing blinds and designing conducive environments, should also be considered. While future studies are necessary to facilitate the implementation of interventions, the potential for these school-level interventions to support adolescent sleep health is evident. Aiming for integration of individual-level regulation and institutional-level intervention of light exposure is necessary for optimal outcomes.

Evaluation of sleep strategies between night shifts in actual shift workers

OBJECTIVES

The aim of this observational study was to examine sleep obtained between consecutive night shifts from shift workers in their natural environment. The goal was to identify the various sleep strategies and the timing, duration, regularity, and quality of sleep associated with the strategies.

METHODS

Participants (N = 33, 23 women, aged 40 ± 15years) reported their sleep information in daily diaries over 2weeks while working at least one series of consecutive night shifts. Sleep timing, duration, quality, and regularity were calculated for each sleep episode between consecutive night shifts.

RESULTS

Based on the reported sleep behavior, shift workers were categorized as either morning, delayed, split- or mixed sleepers. We found significant differences between the groups in timing of sleep, feeling refreshed, and regularity of sleep between consecutive night shifts, whereas duration and subjective soundness of sleep did not show significant differences.

CONCLUSIONS

In this sample, four sleep strategies were observed between consecutive night shifts in actual shift workers. These observations may help design future interventions to improve sleep that are individualized to the worker.

Delaying circadian sleep phase under ultradian light cycle causes time-of-day-dependent alteration of cognition and mood

Light exerts powerful and pervasive effects on physiology and behaviour. These effects can be indirect, through clock synchronization and phase adjustment of circadian rhythms, or direct, independent of the circadian process. Exposure to light at inappropriate times, as commonly experienced in today's society, leads to increased prevalence of circadian, sleep and mood disorders as well as cognitive impairments. In mice, exposure to an ultradian 3.5 h light/3.5 h dark cycle (T7) for several days has been shown to impair behaviour through direct, non-circadian, photic effects, a claim we challenge here. We first confirmed that T7 cycle induces a lengthening of the circadian period resulting in a day by day phase-delay of both activity and sleep rhythms. Spatial novelty preference test performed at different circadian time points in mice housed under T7 cycle demonstrated that cognitive deficit was restrained to the subjective night. Mice under the same condition also showed a modification of stress-induced despair-like behaviour in the forced swim test. Therefore, our data demonstrate that ultradian light cycles cause time-of-day-dependent alteration of cognition and mood through clock period lengthening delaying circadian sleep phase, and not through a direct photic influence. These results are of critical importance for the clinical applications of light therapy in the medical field and for today's society to establish lighting recommendations for shift work, schools, hospitals and homes.

Insomnia Complaints and Perceived Immune Fitness in Young Adults with and without Self-Reported Impaired Wound Healing

Background and Objectives: Adequate sleep and an effective immune system are both essential to maintain a good health status. The current study aimed to determine the nature of insomnia complaints and perceived immune fitness among Dutch young adults with and without self-reported impaired wound healing. Materials and Methods: A total of (n = 2033) Dutch students (83.8% women) completed an online survey. Perceived immune fitness was assessed with a single-item scale and insomnia complaints with the SLEEP-50 insomnia subscale. The sample comprised a control group without self-reported impaired wound healing (n = 1622), a wound infection (WI) group (n = 69), a slow healing wounds (SHW) group (n = 250), and a COMBI group that experienced both WI and SHW (n = 92). Results: Comparisons with the control group revealed that individuals of the SHW and COMBI groups reported significantly poorer perceived immune functioning, increased insomnia complaints and daytime fatigue, and poorer sleep quality. Conclusions: Individuals with self-reported impaired wound healing have a poorer perceived immune functioning, increased insomnia complaints, daytime fatigue, and poorer sleep quality.

Environmental light exposure and mealtime regularity: Implications for human health

Light exposure and mealtime act as cues to the human circadian rhythm, which subsequently regulates various physiological functions in the body. However, modernization alters lifestyles, with changes to social and work-related activities independent of the natural light-dark cycle. This review summarizes the role of light exposure and regular mealtime on bodily processes and, ultimately, metabolic health. Various aspects of light are reviewed, including the type of light (natural/artificial), intensity (lux), spectral composition, time of exposure (night/day), and exposure duration. Further, the possible relationship between light exposure and mealtime irregularity is discussed as a function affecting metabolic health. In essence, research evidence suggests that mealtime regularity and light exposure habits based on the natural occurring light-dark cycle are essential for metabolic health in relation to an aligned circadian rhythm.

Circadian effect of time of anaesthesia on postoperative outcomes in major elective and urgent intervention: a secondary analysis of the Peri-interventional Outcome Study in the Elderly (POSE)

BACKGROUND

A recent prospective study reported a decrease in postoperative mortality when cardiac surgery was started in the afternoon instead of in the morning. In contrast, several large retrospective analyses have not confirmed this finding. Larger prospective studies are required to elucidate the effects of circadian rhythm on postoperative outcomes.

OBJECTIVE

To identify any relation between starting time of anaesthesia/surgery and postoperative outcomes in patients aged 80 years or older to aid in clinical decision making with regard to scheduling surgery.

DESIGN

A multivariable model with a priori defined confounders was constructed to evaluate the impact of anaesthesia starting time on hospital length of stay and postoperative complications.

SETTING

A European multicentre, observational study of outcomes after geriatric anaesthesia from October 2017 to December 2018.

PATIENTS

Patients aged 80 years or older having major elective or urgent intervention with anaesthesia starting time between 7 a.m. and 7 p.m.

MAIN OUTCOME MEASURE

Primary outcome measure was the difference in hospital length of stay after any major elective or urgent morning or afternoon intervention.

RESULTS

We included 3551 patients of whom 2592 had an intervention starting in the morning (7 a.m. to 1 p.m.). These patients, compared with those with interventions in the afternoon (1 p.m. to 7 p.m.), were slightly younger, were less frail but had a longer duration of the intervention. Hospital length of stay or postoperative complications were not different between morning or afternoon interventions. Multivariable analysis showed no impact of time of anaesthesia (morning vs. afternoon) on hospital length of stay or postoperative complications, hazard ratio of 1.03 (95% CI 0.94 to 1.12) and odds ratio of 1.13 (95% CI 0.92 to 1.39), respectively.

CONCLUSION

Our results do not support the hypothesis of circadian effects on postoperative outcomes for elective and urgent major interventions in patients at least 80 years of age.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03152734.

Behavioral and postural analyses establish sleep-like states for mosquitoes that can impact host landing and blood feeding

Sleep is an evolutionarily conserved process that has been described in different animal systems. For insects, sleep characterization has been primarily achieved using behavioral and electrophysiological correlates in a few systems. Sleep in mosquitoes, which are important vectors of disease-causing pathogens, has not been directly examined. This is surprising as circadian rhythms, which have been well studied in mosquitoes, influence sleep in other systems. In this study, we characterized sleep in mosquitoes using body posture analysis and behavioral correlates, and quantified the effect of sleep deprivation on sleep rebound, host landing and blood-feeding propensity. Body and appendage position metrics revealed a clear distinction between the posture of mosquitoes in their putative sleep and awake states for multiple species, which correlated with a reduction in responsiveness to host cues. Sleep assessment informed by these posture analyses indicated significantly more sleep during periods of low activity. Night-time and daytime sleep deprivation resulting from the delivery of vibration stimuli induced sleep rebound in the subsequent phase in day and night active mosquitoes, respectively. Lastly, sleep deprivation suppressed host landing in both laboratory and field settings, and impaired blood feeding of a human host when mosquitoes would normally be active. These results suggest that quantifiable sleep states occur in mosquitoes and highlight the potential epidemiological importance of mosquito sleep.

Sleep, circadian rhythms, and type 2 diabetes mellitus

Over the last 60 years we have seen a significant rise in metabolic disease, especially type 2 diabetes. In the same period, the emergence of electricity and artificial lighting has allowed our behavioural cycles to be independent of external patterns of sunlight. This has led to a corresponding increase in sleep deprivation, estimated to be about 1 hour per night, as well as circadian misalignment (living against the clock). Evidence from experimental animals as well as controlled human subjects have shown that sleep deprivation and circadian misalignment can both directly drive metabolic dysfunction, causing diabetes. However, the precise mechanism by which these processes contribute to insulin resistance remains poorly understood. In this article, we will review the new literature in the field and propose a model attempting to reconcile the experimental observations made. We believe our model will serve as a useful point of reference to understand how metabolic dysfunction can emerge from sleep or circadian rhythm disruptions, providing new directions for research and therapy.

Association of sleep disturbance with diabetic retinopathy

PURPOSE

Diabetes mellitus (DM) patients are more likely to experience sleep disturbances than normal. Sleep disturbances may contribute to the development of diabetic retinopathy (DR) by higher inflammatory markers in circulation. We investigated the association between sleep quality and DR.

METHODS

Institutional case control study with type 2 DM patients of <10 years duration and HbA1c ⩽8%; 70 cases with DR and 70 controls without DR (NODR) (power 0.8). Sleep quality was assessed by Pittsburg sleep quality index (PSQI) questionnaire and compared.

RESULTS

Cronbach's alpha was 0.777 with high internal homogeneity. Global PSQI score in DR (7.44 ± 3.99; 95%CI 6.88, 9.42) was more than in NODR (4.30 ± 3.26; 95%CI 3.87, 6.45) (p < 0.001). All sleep disturbance scores were more in DR except sleep duration. Poor sleep (PSQI score>5) was more prevalent in DR (p = 0.000) and associated with increasing DR severity (p = 0.026). Normal sleep latency was recorded in 78.57% and 42.85% patients in NODR and DR respectively (p < 0.001). Severe difficulty in subjective sleep quality (p = 0.024), sleep latency (p = 0.002) and daytime dysfunction (p < 0.001) was seen more in DR. Elevated daytime dysfunction was observed with increasing DR severity (p = 0.008). The optimal cut-off for global PSQI score and sleep latency for DR was 5.5 (OR: 5.97; 95%CI 2.86, 12.47) and 25 min(OR: 4.89; 95%CI 2.32, 10.26) respectively.

CONCLUSION

Sleep disturbance is positively associated with DR. Our study identifies cut off value for DR of a modifiable parameter like sleep latency. It emphasizes the need of sleep quality assessment for risk assessment of DR.

Holistic Needs Assessment of Cancer Survivors-Supporting the Process Through Digital Monitoring of Circadian Physiology

The year 2022 could represent a significant juncture in the incorporation of mHealth solutions in routine cancer care. With the recent global COVID-19 pandemic leading a surge in both observation- and intervention-based studies predominantly aimed at remote monitoring there has been huge intellectual investment in developing platforms able to provide real time analytics that are readily usable. Another fallout from the pandemic has seen record waiting times and delayed access to cancer therapies leading to exhausting pressures on global healthcare providers. It seems an opportune time to utilize this boom in platforms to offer more efficient “at home” clinical assessments and less “in department” time for patients. Here, we will focus specifically on the role of digital tools around cancer survivorship, a relevant aspect of the cancer journey, particularly benefiting from integrative approaches. Within that context a further concept will be introduced and that is of the likely upsurge in circadian-based interpretation of continuous monitoring and the engendered therapeutic modifications. Chronobiology across the 24-hour span has long been understood to control key bodily aspects and circadian dysregulation plays a significant role in the risk of cancer and also the response to therapy and therefore progressive outcome. The rapid improvement in minimally invasive monitoring devices is, in the opinion of the authors, likely to advance introducing chronobiological amendments to routine clinical practices with positive impact on cancer survivors.

Obstructive Sleep Apnoea, Other Sleep Parameters and Diabetic Retinopathy

PURPOSE OF REVIEW

To summarise the association between obstructive sleep apnoea and diabetic retinopathy and diabetic macular oedema. To examine the effects of other sleep parameters on diabetic retinopathy and diabetic macular oedema. To discuss the pathophysiology of diabetic eye changes and how it is related to obstructive sleep apnoea.

RECENT FINDINGS

Conflicting data exists in terms of the association of diabetic eye changes with sleep apnoea and/or other sleep parameters. Various cross-sectional studies show PDR to be associated with the prevalence of OSA. Patients who underwent continuous positive airway pressure (CPAP) treatment were significantly less likely to develop pre/proliferative DR. Secondary sleep parameters generally are not associated with DR except for long duration of sleep. Differences in reporting could be due to the different thresholds set to define OSA/ODI and severity of DR/DME, in addition to factors used in multivariate analysis. There is a need for further studies with long-term follow-up and to assess the impact of CPAP on the development and progression of diabetic eye change(s).

Night Shift and Decreased Brain Activity of ICU Nurses: A Near-Infrared Spectroscopy Study

Background: Shift working is associated with a profound desynchronization of circadian rhythm and in particular, night-shift work disrupts normal circadian physiology. Sleep deprivation affects the functioning of certain brain areas and thus impairs cognitive performance. The purpose of this study was to investigate the effects of the night shift on cognitive performance and cerebral oxygenation/haemodynamics. Methods: A prospective, observational, comparative, randomized and cross-over study was carried out. A total of 74 intensive care unit nurses in Spain were included in the study. The following variables were measured: sociodemographic, burnout, anxiety, baseline cerebral oxygenation levels on night and day shift using a near-infrared spectroscopy system and cognitive task performance during a verbal fluency task to evaluate the alterations in the prefrontal cortex, assessed as changes in regional saturation index. Results: The average regional saturation index decreased significantly in the night shift (r = 0.560, p < 0.001). The ICU nurses showed a significant decrease in the verbal fluency test on average (8.53 ± 8.49, p < 0.001) and, in general, there was also a significant increase in anxiety score (3.17 ± 7.56, p = 0.001). Conclusions: Sleep deprivation during the night shift was considered to be related to decreased dorsolateral PFC reactivity. After the night shift, the nurses showed a decrease in prefrontal cortex activity and in cognitive performance.

Long-term variable photoperiod exposure impairs the mPFC and induces anxiety and depression-like behavior in male wistar rats

Long-term shift work can cause circadian misalignment, which has been linked to anxiety and depression. However, the associated pathophysiologic changes have not been described in detail, and the mechanism underlying this association is not fully understood. To address these points, we used a rat model of CM induced by long-term variable photoperiod exposure [L-VP] (ie, for 90 days). We compared the numbers of neurons, astrocytes, and dendritic spines; dendrite morphology; long-term potentiation (LTP), long-term depression (LTD) and paired-pulse ratio (PPR); expression of glutamate receptor [N-methyl-d-aspartate receptor (NMDAR) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)] subunits and brain-derived neurotrophic factor (BDNF) in the medial prefrontal cortex (mPFC); and the anxiety and depression behaviors between rats in the circadian misalignment (CM) and circadian alignment (CA, with normal circadian rhythm) groups. The results showed that L-VP reduced the number of neurons and astrocytes in the mPFC and decreased the number of dendritic spines, dendrite complexity, LTP, LTD, PPR, and expression of glutamate receptors (GluR1, GluR2, GluR3, NMDAR2A, and NMDAR2B) and BDNF in the mPFC. L-VP also induced anxiety and depression-like behaviors, as measured by the open field test, elevated plus-maze, sucrose preference test, and forced swim test. These results suggest that CM induces a loss of neurons and astrocytes and synaptic damage in surviving pyramidal cells in the mPFC might be involved in the pathophysiology of anxiety and depression.

Understanding the association between sleep, shift work and COVID-19 vaccine immune response efficacy: Protocol of the S-CORE study

This protocol describes an innovative study to investigate the relationship between sleep, shift work and the immune response to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2; coronavirus disease 2019 [COVID-19]) vaccination. As the COVID-19 pandemic is a global crisis with devastating health, social and economic impacts, there is a pressing need for effective vaccination programmes. Previous influenza and hepatitis vaccination studies suggest that lack of sleep can negatively alter immune responsiveness, while circadian misalignment most likely may also play an important role in the immune response to vaccination. Our present study will be the first to address this question in actual shift workers and in relation to COVID-19 vaccination. We hypothesise that the occurrence of recent night shifts and diminished sleep will negatively alter the immune response to vaccination in shift workers compared to dayworkers. We aim to recruit 50 shift workers and 50 dayworkers. Participants will receive an mRNA-based vaccination, through the Dutch vaccination programme. To assess immune responsiveness, blood will be drawn at baseline (before first vaccination), 10 days after first vaccination, the day prior to the second vaccination; and 28 days, 6 and 12 months after the second vaccination. Actigraphy and daily sleep e-diaries will be implemented for 7 days around each vaccination to assess sleep. The Pittsburgh Sleep Quality Index will be used to monitor sleep in the long term. Optimising the efficacy of the COVID-19 vaccines is of outmost importance and results of this study could provide insights to develop sleep and circadian-based interventions to enhance vaccination immunity, and thereby improve global health.

Sleep in Older Adults and Its Possible Relations With COVID-19

Since the beginning of the COVID-19 pandemic, older adults have been found to be a highly vulnerable group, with a higher prevalence of severe cases and negative outcomes. Research has focused on the reasons why older adults are at greater risk; Sleep-related factors have been suggested as one possible explanation for this. An individual's sleep pattern undergoes significant changes over the course of their life. In older adults a specific sleep profile can be observed, one characterized by advanced sleep timing, a morningness preference, longer sleep-onset latency, shorter overall sleep duration, increased sleep fragmentation, reduced slow-wave sleep and, increased wake time after sleep onset. Additionally, an increased prevalence of sleep disorders can be observed, such as obstructive sleep apnea and insomnia. Previous research has already linked sleep disorders (especially sleep apnea) with COVID-19, but few studies have focused specifically on the older population. We believe that the intrinsic sleep patterns of older adults, and the prevalence of sleep disorders in this population, may be important factors that could explain why they are at a greater risk of negative COVID-19 outcomes. In this review, we discuss the relationship between sleep and COVID-19 among older adults, focusing on three different aspects: (1) Sleep-related issues that might increase the likelihood of getting infected by SARS-COV-2; (2) Sleep disturbances that might increase the predisposition to worse COVID-19 prognosis and outcomes; and (3) COVID-19-related aspects affecting community-dwelling older adults, such as social isolation, quarantine, and home confinement, among others, that might impact sleep.

Should We Re-think Regulations and Standards for Lighting at Workplaces? A Practice Review on Existing Lighting Recommendations

Nowadays lighting projects often include temporal variations of the light, both spectrally and in terms of intensity to consider non-visual effects of light on people. However, as of today there are no specific regulations. Compliance with common lighting standards that address visual aspects of light, often means that only little non-visually effective light reaches the eye. In this practice review we confront existing regulations and standards on visual lighting aspects with new recommendations on non-visual aspects and highlight conflicts among them. We conclude with lighting recommendations that address both aspects.

The evening light environment in hospitals can be designed to produce less disruptive effects on the circadian system and improve sleep

STUDY OBJECTIVES

Blue-depleted lighting reduces the disruptive effects of evening artificial light on the circadian system in laboratory experiments, but this has not yet been shown in naturalistic settings. The aim of the current study was to test the effects of residing in an evening blue-depleted light environment on melatonin levels, sleep, neurocognitive arousal, sleepiness, and potential side effects.

METHODS

The study was undertaken in a new psychiatric hospital unit where dynamic light sources were installed. All light sources in all rooms were blue-depleted in one half of the unit between 06:30 pm and 07:00 am (melanopic lux range: 7-21, melanopic equivalent daylight illuminance [M-EDI] range: 6-19, photopic lux range: 55-124), whereas the other had standard lighting (melanopic lux range: 30-70, M-EDI range: 27-63, photopic lux range: 64-136), but was otherwise identical. A total of 12 healthy adults resided for 5 days in each light environment (LE) in a randomized cross-over trial.

RESULTS

Melatonin levels were less suppressed in the blue-depleted LE (15%) compared with the normal LE (45%; p = 0.011). Dim light melatonin onset was phase-advanced more (1:20 h) after residing in the blue-depleted LE than after the normal LE (0:46 h; p = 0.008). Total sleep time was 8.1 min longer (p = 0.032), rapid eye movement sleep 13.9 min longer (p < 0.001), and neurocognitive arousal was lower (p = 0.042) in the blue-depleted LE. There were no significant differences in subjective sleepiness (p = 0.16) or side effects (p = 0.09).

CONCLUSIONS

It is possible to create an evening LE that has an impact on the circadian system and sleep without serious side effects. This demonstrates the feasibility and potential benefits of designing buildings or hospital units according to chronobiological principles and provide a basis for studies in both nonclinical and clinical populations.

Sleep problems are related to commuting accidents rather than to workplace accidents

Background

This study aimed to verify the relationships between sleep problems and both commuting and workplace accidents in workers of both sexes.

Methods

The study was carried out with a sample of workers (n = 2993; 50.2% female) from the Chilean Quality of Life Survey (ENCAVI) 2015–2016, while the rates of both workplace and commuting accidents were extracted from the statistics of the Superintendence of Social Security (SUSESO 2015; 180,036 and 52,629 lost-time accidents, respectively).

Results

Chilean workers sleep less than the rest of the people in the country (M_W = 7.14 vs. M_O = 7.33; t (6789) = − 5.19; p < .001), while the Chilean people as a whole sleep less compared to those of other countries (7.24 h per day). Likewise, it was found that sleep problems are more strongly related to commuting than to workplace accidents. In this vein, sleep quantity can explain 24% of the variance in commuting accidents’ rates (Stepwise Method; R² = .30, F (1.14) = 5.49, p < .05; β = −.55, p < .05), by using aggregated data with all types of commuting roles (driver of a vehicle, a passenger of public or private transport, or as a pedestrian).

Conclusions

Our findings show that sleep quantity has a more robust relationship with commuting than workplace accidents, a neglected issue so far. Future prevention programs should emphasize sleep hygiene and focus on commuting to and from work.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-10737-5.

Diversity of intrinsically photosensitive retinal ganglion cells: circuits and functions

The melanopsin-expressing, intrinsically photosensitive retinal ganglion cells (ipRGCs) are a relatively recently discovered class of atypical ganglion cell photoreceptor. These ipRGCs are a morphologically and physiologically heterogeneous population that project widely throughout the brain and mediate a wide array of visual functions ranging from photoentrainment of our circadian rhythms, to driving the pupillary light reflex to improve visual function, to modulating our mood, alertness, learning, sleep/wakefulness, regulation of body temperature, and even our visual perception. The presence of melanopsin as a unique molecular signature of ipRGCs has allowed for the development of a vast array of molecular and genetic tools to study ipRGC circuits. Given the emerging complexity of this system, this review will provide an overview of the genetic tools and methods used to study ipRGCs, how these tools have been used to dissect their role in a variety of visual circuits and behaviors in mice, and identify important directions for future study.

Let there be blue-depleted light: in-patient dark therapy, circadian rhythms and length of stay

Light is the most important environmental influence (zeitgeber) on the synchronization of the circadian system in humans. Excess light exposure during the evening and night-time affects secretion of the hormone melatonin, which in turn modifies the temporal organization of circadian rhythms, including the sleep–wake cycle. As sleep disturbances are prominent in critically ill medical and psychiatric patients, researchers began to examine the impact of light exposure on clinical outcomes and length of hospitalization. In psychiatric inpatients, exposure to bright morning light or use of blue blocking glasses have proved useful interventions for mood disorders. Recently, knowledge about light and the circadian system has been applied to the design of inpatient facilities with dynamic lighting systems that change according to time of day. The installation of ‘circadian lighting’ alongside technologies for monitoring sleep–wake patterns could prove to be one of the most practical and beneficial innovations in inpatient psychiatric care for more than half a century.

The Effect of Sleep Hygiene and Sleep Deterioration on Quality of Life in Shiftworking Healthcare Professionals

Introduction

Deterioration in sleep quality and sleep hygiene may result in impairments on mental and physical health leading to deterioration of quality of life (QoL) in healthcare shift workers. We aimed to determine the presence of sleep deterioration as well as poor sleep hygiene, and if any, the effects of these on health-related outcomes.

Methods

This study prospectively included healthcare professionals who did and did not work shifts (n=90 and n=66, respectively). The participants completed the Pittsburgh Sleep Quality Index (PSQI), Sleep Hygiene Index (SHI), Epworth Daytime Sleepiness Scale (EDSS), Short Form-36 quality of life scale (SF-36), and the Beck depression (BD) and Beck anxiety (BA) scales.

Results

Although the total PSQI scores showed a tendency to increase in shift workers, no significant differences were observed in total scores as well as subdivisions, except for an increase in sleep latency. Increased SHI total score in shift workers were represent more deteriorated sleep hygiene behavior (p=0.002). Increased needs of daytime nap, variability of both go and get out of bed and stay in bed longer than usual were recorded respectively (p: 0.001, p: 0.001, p: 0.001, p: 0.001, p: 0.001). SHI had prominent effects on QoL parameters such as vitality (r=-0.284, p=0.007), social function (r=-0.323, p=0.002), mental health (r=-0.274, p=0.009), and calculated mental component total score (r=-0.302, p=0.004).

Conclusion

In our study, we clearly detected prolonged sleep latency and poor sleep hygiene in shift workers which should be responsible for the deterioration of QoL.

Extracellular Acidosis Promotes Metastatic Potency via Decrease of the BMAL1 Circadian Clock Gene in Breast Cancer

Circadian oscillation is an essential process that influences many physiological and biological mechanisms and a decrease of circadian genes is associated with many diseases such as cancer. Despite many efforts to identify the detailed mechanism for decreasing circadian genes and recovering reduced circadian genes in cancer, it is still largely unknown. We found that BMAL1 was reduced in tumor hypoxia-induced acidosis, and recovered by selectively targeting acidic pH in breast cancer cell lines. Surprisingly, BMAL1 was reduced by decrease of protein stability as well as inhibition of transcription under acidosis. In addition, melatonin significantly prevented acidosis-mediated decrease of BMAL1 by inhibiting lactate dehydrogenase-A during hypoxia. Remarkably, acidosis-mediated metastasis was significantly alleviated by BMAL1 overexpression in breast cancer cells. We therefore suggest that tumor hypoxia-induced acidosis promotes metastatic potency by decreasing BMAL1, and that tumor acidosis could be a target for preventing breast cancer metastasis by sustaining BMAL1.

Sleep and Reproductive Health

The reproductive function of humans is regulated by several sex hormones which are secreted in synergy with the circadian timing of the body. Sleep patterns produce generic signatures that physiologically drive the synthesis, secretion, and metabolism of hormones necessary for reproduction. Sleep deprivation among men and women is increasingly reported as one of the causes of infertility. In animal models, sleep disturbances impair the secretion of sexual hormones thereby leading to a decrease in testosterone level, reduced sperm motility and apoptosis of the Leydig cells in male rats. Sleep deprivation generates stressful stimuli intrinsically, due to circadian desynchrony and thereby increases the activation of the Hypothalamus-Pituitary Adrenal (HPA) axis, which, consequently, increases the production of corticosterone. The elevated level of corticosteroids results in a reduction in testosterone production. Sleep deprivation produces a commensurate effect on women by reducing the chances of fertility. Sleeplessness among female shift workers suppresses melatonin production as well as excessive HPA activation which results in early pregnancy loss, failed embryo implantation, anovulation and amenorrhea. Sleep deprivation in women has also be found to be associated with altered gonadotropin and sex steroid secretion which all together lead to female infertility. Poor quality of sleep is observed in middle-aged and older men and this also contributes to reduced testosterone concentrations. The influence of sleep disturbances post-menopausal is associated with irregular synthesis and secretion of female sex steroid hormones.

The Role of Daylight for Humans: Gaps in Current Knowledge

Daylight stems solely from direct, scattered and reflected sunlight, and undergoes dynamic changes in irradiance and spectral power composition due to latitude, time of day, time of year and the nature of the physical environment (reflections, buildings and vegetation). Humans and their ancestors evolved under these natural day/night cycles over millions of years. Electric light, a relatively recent invention, interacts and competes with the natural light-dark cycle to impact human biology. What are the consequences of living in industrialised urban areas with much less daylight and more use of electric light, throughout the day (and at night), on general health and quality of life? In this workshop report, we have classified key gaps of knowledge in daylight research into three main groups: (I) uncertainty as to daylight quantity and quality needed for "optimal" physiological and psychological functioning, (II) lack of consensus on practical measurement and assessment methods and tools for monitoring real (day) light exposure across multiple time scales, and (III) insufficient integration and exchange of daylight knowledge bases from different disciplines. Crucial short and long-term objectives to fill these gaps are proposed.

The Effects of Different Feeding Routines on Welfare in Laboratory Mice

The accepted norm in most laboratories around the globe is feeding laboratory mice an ad libitum diet, although several health impairments are well-established. In contrast, reducing the animals' body weight by feeding them less food once per day (referred to as 24 h schedule) has been shown to enhance life span and reduce disease susceptibility. Against this background, this study aimed at systematically investigating the effects of different feeding routines. Therefore, three feeding routines were compared to the standard ad libitum feeding and effects on body weight development and welfare were investigated in male C57BL/6J mice. In particular, a 24 h schedule group, an AUTO group, characterized by an automated supply of small pieces of food all over the day, and a 4 h removal group, characterized by daily removal of food for 4 h, were studied. While the removal of food for 4 h per day did not lead to a reduction of body weight, and hence is unlikely to prevent negative effects of overfeeding, both the 24 h schedule group and the AUTO group led to the aspired body weight reduction. In the AUTO group, however, higher levels of corticosterone metabolites and stereotypies were observed, implying a rather negative impact on welfare. By contrast, no distinct negative effects of a 24 h schedule were found. Studies like this underline the general need for evidence-based severity assessments of any procedure involving living animals.

Impact of Diabetic Retinopathy on Sleep, Mood, and Quality of Life

Purpose

Diabetic retinopathy (DR) is associated with retinal neuronal and vascular damage. DR has previously been shown to affect the photosensitive retinal ganglion cells (pRGCs). PRGCs are essential for the entrainment of circadian rhythms; thus, DR progression could lead to worsening sleep quality and mood. We investigate the relationship between increasing DR severity, and its impact on sleep quality and mood.

Methods

A total of 430 participants with DR, and 303 healthy controls with no ocular disease or preexisting sleep disorders were recruited. DR severity was grouped as follows: 1, mild nonproliferative (NPDR); 2, moderate/severe NPDR; and 3, proliferative diabetic retinopathy (PDR). Sleep, mood, and quality of life were assessed using the Pittsburgh Sleep Quality Index (PSQI), quality of life (SF-36), and Hospital Anxiety and Depression Score (HADS) questionnaires. Data were analyzed by severity of DR, and correlated with sleep, QOL, and mood and compared to controls.

Results

No significant difference between PSQI scores in the DR group or the control group was identified despite severity of DR. Mean anxiety and depression scores were within the normal range for both groups. Despite a lower general health and physical function, the DR group had lower anxiety scores than controls.

Conclusions

These data show that even in severe DR, sleep quality is similar to controls. However, this could be explained by the majority of individuals in this study having good visual acuities in the better eye with a residual population of pRGCs remaining unaffected by DR.

The erythrocyte membrane stability is associated with sleep time and social jetlag in shift workers

The osmotic stability of the erythrocyte membrane (OSEM) has been associated with changes in lipid profile, blood glucose and blood pressure. Changes in these parameters are very frequent in shift workers, possibly because of the lack of synchronization of biological rhythms, which results in the social jetlag. However, the existence of association between OSEM and circadian misalignment has not been investigated in this population. Therefore, this study investigated whether shift work, sleep time and social jetlag (SJL) are associated with biochemical and hematological variables. A population consisting of 79 men working at night (n = 37) or during the day (n = 42), aged between 21 and 65 years and with a mean BMI of 27.56 ± 4.0 kg/m², was investigated cross-sectionally in relation to sleep time, SJL, anthropometric (height, weight and waist circumference) and blood variables, with emphasis on the OSEM. SJL was calculated by the absolute difference between the midpoint of sleep on work and rest days. The Generalized Linear Model (GzLM) was used to investigate the existence of associations between SJL and average sleep time in relation to the analyzed variables. Workers without SJL presented lower baseline lysis values of erythrocytes in isotonic medium in relation to workers with SJL. In addition, workers who slept on average less than 6 hours had higher OSEM, and higher total and LDL-cholesterol in relation to those who slept more than 6 hours, regardless of the shift. It is possible that the association of sleep deprivation and SJL with erythrocyte membrane stability is mediated through changes in the lipid profile.

A pragmatic effectiveness randomized controlled trial of the duration of psychiatric hospitalization in a trans-diagnostic sample of patients with acute mental illness admitted to a ward with either blue-depleted evening lighting or normal lighting conditions

Background

There is increasing recognition of the need to stabilize sleep-wake cycles in individuals with major mental disorders. As such, clinicians and researchers advocate the use of interventions targeted at sleep and circadian dysrhythmias as an adjunct to the standard treatments offered for acute illness episodes of a broad range of diagnoses. To determine the trans-diagnostic generalizability of chronotherapy, we explore the benefits of admitting individuals with an acute illness episode to a psychiatric inpatient unit where changes in light exposure are integrated into the therapeutic environment.

Methods/design

A two-arm, pragmatic effectiveness, randomized controlled treatment trial, where individuals admitted for acute inpatient psychiatric care will be allocated to a ward with blue-depleted evening light or to a ward with the same layout and facilities but lacking the new lighting technology. The trial will test whether the experimental lighting conditions offer any additional benefits beyond those associated with usual treatment in an acute psychiatric inpatient unit. The main objectives are to examine any differences between groups in the mean duration of hospitalization in days. Additional analyses will compare group differences in symptoms, functioning, medication usage, and side effects and whether length of stay is associated with stability of sleep-wake cycles and circadian rhythms. Ancillary investigations should determine any benefits according to diagnostic subgroups and potential drawbacks such as any adverse effects on the well-being of professionals working across both wards.

Discussion

This unit offers a unique opportunity to explore how exposure to different lighting conditions may modify sleep-wake cycles and how any changes in sleep-wake cycle may impact on the clinical and functional outcomes of individuals experiencing an acute episode of a severe mental disorder that requires inpatient care. The findings could influence the future design of hospital units offering care to patients with mental or physical disorders.

Trial registration

ClinicalTrials.gov, ID: NCT03788993. Retrospectively registered on 28 December 2018.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3582-2) contains supplementary material, which is available to authorized users.

Is circadian rhythmicity a prerequisite to coma recovery? Circadian recovery concomitant to cognitive improvement in two comatose patients

Circadian rhythmicity (CR) is involved in the regulation of all integrated functions, from sleep-wake cycle regulation to metabolic function, mood and cognition. However, the interdependence of CR, cognition and consciousness has been poorly addressed. To clarify the state of CR in coma and to determine the chronological relationship between its recovery and consciousness after brain lesions, we conducted a longitudinal observational study investigating how the state of CR was chronologically related with the recovery of behavioural wakefulness, cognition and/or awareness. Among 16 acute comatose patients, we recruited two 37-year-old patients with a persistent disorder of consciousness, presenting diencephalic lesions caused by severe traumatic brain injuries. Two biological urinary markers of CR were explored every 2 hours during 24 hours (6-sulfatoxymelatonin, free cortisol) with a dedicated methodology to extract the endogenous component of rhythmicity (environmental light recording, near-constant-routine protocol, control of beta-blockers). They presented an initial absence of rhythmic secretions and a recovered CR 7-8 months later. This recovery was not associated with the restoration of behavioural wakefulness, but with an improvement of cognition and awareness (up to the minimally conscious state). MRI showed a lesion pattern compatible with the interruption of either the main hypothalamic-sympathetic pathway or the accessory habenular pathway. These results suggest that CR may be a prerequisite for coma recovery with a potential but still unproven favourable effect on brain function of the resorted circadian melatonin secretion and/or the functional recovery of the suprachiasmatic nucleus (SCN). Assessing circadian functions by urinary melatonin should be further explored as a biomarker of cognition reappearance and investigated to prognosticate functional recovery.

Gestational jet lag predisposes to later-life skeletal and cardiac disease

Circadian rhythm disturbance (CRD) increases the risk of disease, e.g. metabolic syndrome, cardiovascular disease, and cancer. In the present study, we investigated later life adverse health effects triggered by repeated jet lag during gestation. Pregnant mice were subjected to a regular light-dark cycle (CTRL) or to a repeated delay (DEL) or advance (ADV) jet lag protocol. Both DEL and ADV offspring showed reduced weight gain. ADV offspring had an increased circadian period, and an altered response to a jet lag was observed in both DEL and ADV offspring. Analysis of the bones of adult male ADV offspring revealed reduced cortical bone mass and strength. Strikingly, analysis of the heart identified structural abnormalities and impaired heart function. Finally, DNA methylation analysis revealed hypermethylation of miR17-92 cluster and differential methylation within circadian clock genes, which correlated with altered gene expression. We show that developmental CRD affects the circadian system and predisposes to non-communicable disease in adult life.

Developmental pathways towards mood disorders in adult life: Is there a role for sleep disturbances?

INTRODUCTION

Mood disorders are among the most prevalent and serious mental disorders and rank high among to the leading global burdens of disease. The developmental psychopathology framework can offer a life course perspective on them thus providing a basis for early prevention and intervention. Sleep disturbances, are considered risk factors for mood disorders across childhood, adolescence and adulthood. Assuming that sleep disturbances may play a pivotal role in the pathogenesis of mood disorders from a life course point of view, we reviewed the data on developmental pathways towards mood disorders in adult life in relation to sleep disturbances.

METHOD

From February 2017, a systematic search was conducted in PubMed, PsycINFO and Embase electronic databases for literature on developmental pathways to mood disorders in adult life in relation to sleep disturbances and to 1) pre-natal stress, 2) early brain developmental processes, and 3) temperaments, character and attachment style.

RESULTS

Eleven, 54 and 15 articles were respectively selected.

CONCLUSIONS

Experimental and clinical studies revealed that exposure to prenatal/early life stress results in sleep disturbances such as poor sleep and altered circadian regulation phases and may predict or even precipitate mood disorders in adulthood. Chronic sleep disruption may interfere with neuronal plasticity, connectivity and the developing brain thus contributing to the development of mood disorders. In addition sleep and circadian dysregulations have been shown to be related to those temperaments, character and attachment styles which are considered precursors of mood disorders. Sleep and circadian behaviours may serve as early targets regarding mood disorders.

Riding the Rhythm of Melatonin Through Pregnancy to Deliver on Time

Pregnancy is influenced by the circadian ("circa" or approximately; diēm or day) system, which coordinates physiology and behavior with predictable daily changes in the environment such as light/dark cycles. For example, most species deliver around a particular time of day. In mammals, circadian rhythms are controlled by the master circadian pacemaker, the suprachiasmatic nucleus. One key way that the suprachiasmatic nucleus coordinates circadian rhythms throughout the body is by regulating production of the sleep-promoting hormone melatonin. Serum melatonin concentration, which peaks at night and is suppressed during the day, is one of the best biological indicators of circadian timing. Circadian misalignment causes maternal disturbances in the temporal organization of many physiological processes including melatonin synthesis, and these disturbances of the circadian system have been linked to an increased risk for pregnancy complications. Here, we review evidence that melatonin helps regulate the maternal and fetal circadian systems and the timing of birth. Finally, we discuss the potential for melatonin-based therapeutic strategies to alleviate poor pregnancy outcomes such as preeclampsia and preterm birth.

The effect of cranial electrotherapy stimulation on sleep in healthy women

OBJECTIVE

Cranial electrotherapy stimulation (CES) is considered to be a potential treatment for insomnia. Women are more likely to suffer from insomnia than men. Therefore we studied the effect of CES on sleep efficiency in young healthy women.

METHODS

A randomized, controlled clinical study was conducted on 40 women (age 18-35 years) without sleep disorders. Each subject underwent two nights of polysomnography in a sleep center. During the second night, we applied CES with a commercial device (Alpha-Stim 100) using either active or sham stimulation (double-blinded). Sleep was evaluated with respect to differences between the active and sham modes. Sleep electroencephalogram (EEG) analysis was applied to determine frequency changes.

RESULTS

In our study we found no evidence of any direct influence of the Alpha-Stim 100 on sleep. After application of CES, we determined no significant differences between the active group and the control group (sham). Using EEG spectral analysis there was evidence of a frequency-lowering influence on the low-α frequency band (8-10 Hz).

CONCLUSIONS

At most we may assume a reproducible effect on the α frequency measured in the EEG for application of CES with current levels  >100 µA and presumably also with frequencies  >0.5 Hz, with application directly at the cranium. We found no influence on sleep parameters. The effect on the low-α band evidenced in quantitative EEG analysis would require further investigation in a study with sufficient effect size.

SIGNIFICANCE

This is the first study to investigate the effects of CES with polysomnography during and after therapy. Our study contributes to the few controlled trials that have been conducted to study CES and its effects on the EEG α band. Highlights • This is the first study to investigate the effects of the Alpha-Stim in polysomnography during and subsequent to therapy. • In a quantitative electroencephalogram analysis we studied the data obtained for systematic changes. • To minimize placebo effects in patients with sleep disorders, we conducted the tests on subjects without such disorders.

Effects of experimental sleep deprivation on aggressive, sexual and maternal behaviour in animals: a systematic review protocol

Objective

Because of the relevance for the research on sleep deprivation and human behaviour, many preclinical studies have been conducted on aggressive, sexual and maternal behaviours in this field. Considering the available data and the complexity of the factors involved, the most appropriate way to summarise the effects of sleep deprivation on these behaviours is through systematic reviews and meta-analyses. This article describes the protocol for three independent systematic reviews and meta-analyses, evaluating the effects of sleep deprivation on aggressive, sexual and maternal behaviours in animals.

Search strategy

A bibliographic search will be performed in four databases: Pubmed, Scopus, Web of Science and Psychinfo, searching for three domains: sleep deprivation (as the intervention), animals (as the population) and behaviour (as the outcome).

Screening and annotation

Titles and abstracts will first be screened, followed by analysis of the full text and data extraction.

Data management and reporting

SYstematic Review Centre for Laboratory Animal Experimentation ’s risk of bias tool will be used to evaluate risk of bias; visual analysis of funnel plots, Egger’s regression and trim-and-fill will be employed to evaluate publication bias. Effect sizes will be calculated from the articles by either direct or standardised mean difference, depending on the nature of the data. Overall estimates will then be calculated using a random effects model. Heterogeneity will be assessed using both I² index and Cochran’s Q test. These meta-analyses should be useful to summarise the available data on the relationship between sleep deprivation and behaviour, providing a solid background for future behavioural sleep deprivation experiments, improving their validity.

Making Memories: Why Time Matters

In the last decade advances in human neuroscience have identified the critical importance of time in creating long-term memories. Circadian neuroscience has established biological time functions via cellular clocks regulated by photosensitive retinal ganglion cells and the suprachiasmatic nuclei. Individuals have different circadian clocks depending on their chronotypes that vary with genetic, age, and sex. In contrast, social time is determined by time zones, daylight savings time, and education and employment hours. Social time and circadian time differences can lead to circadian desynchronization, sleep deprivation, health problems, and poor cognitive performance. Synchronizing social time to circadian biology leads to better health and learning, as demonstrated in adolescent education. In-day making memories of complex bodies of structured information in education is organized in social time and uses many different learning techniques. Research in the neuroscience of long-term memory (LTM) has demonstrated in-day time spaced learning patterns of three repetitions of information separated by two rest periods are effective in making memories in mammals and humans. This time pattern is based on the intracellular processes required in synaptic plasticity. Circadian desynchronization, sleep deprivation, and memory consolidation in sleep are less well-understood, though there has been considerable progress in neuroscience research in the last decade. The interplay of circadian, in-day and sleep neuroscience research are creating an understanding of making memories in the first 24-h that has already led to interventions that can improve health and learning.