Sleep-wake Behavior Research Articles

NREM–REM alternation complicates transitions from napping to non-napping behavior in a three-state model of sleep–wake regulation

The temporal structure of human sleep changes across development as it consolidates from the polyphasic sleep of infants to the single nighttime sleep episode typical in adults. Experimental studies have shown that changes in the dynamics of sleep need may mediate this developmental transition in sleep patterning, however, it is unknown how sleep architecture interacts with these changes. We employ a physiologically-based mathematical model that generates wake, rapid eye movement (REM) and non-REM (NREM) sleep states to investigate how NREM–REM alternation affects the transition in sleep patterns as the dynamics of the homeostatic sleep drive are varied. To study the mechanisms producing these transitions, we analyze the bifurcations of numerically-computed circle maps that represent key dynamics of the full sleep–wake network model by tracking the evolution of sleep onsets across different circadian (∼ 24 h) phases. The maps are non-monotonic and discontinuous, being composed of branches that correspond to sleep–wake cycles containing distinct numbers of REM bouts. As the rates of accumulation and decay of the homeostatic sleep drive are varied, we identify the bifurcations that disrupt a period-adding-like behavior of sleep patterns in the transition between biphasic and monophasic sleep. These bifurcations include border collision and saddle–node bifurcations that initiate new sleep patterns, period-doubling bifurcations leading to higher-order patterns of NREM–REM alternation, and intervals of bistability of sleep patterns with different NREM–REM alternations. Furthermore, patterns of NREM–REM alternation exhibit variable behaviors in different regimes of constant sleep–wake patterns. Overall, the sequence of sleep–wake behaviors, and underlying bifurcations, in the transition from biphasic to monophasic sleep in this three-state model is more complex than behavior observed in models of sleep–wake regulation that do not consider the dynamics of NREM–REM alternation. These results suggest that interactions between the dynamics of the homeostatic sleep drive and the dynamics of NREM–REM alternation may contribute to the wide interindividual variation observed when young children transition from napping to non-napping behavior.

Modulation of cholinergic, GABA-ergic and glutamatergic components of superior colliculus affect REM sleep in rats

The superior colliculus (SC) is associated with visual attention, spatial navigation, decision making, escape and approach responses, some of which are important for defence and survival in rodents. SC helps in initiating and controlling saccadic eye movements and gaze during wakefulness. It is also activated during rapid eye movement (REM) sleep associated rapid eye movements (REMs). To investigate the contribution of SC in sleep-wake behaviour, we have demonstrated that manipulation of SC with scopolamine, carbachol, muscimol, picrotoxin and MK-801 decreased the amount of REM sleep. We observed that scopolamine and picrotoxin as well as muscimol decreased REM sleep frequency. MK-801 decreased percent amount of REM sleep, however, neither the frequency nor the duration/episode was affected. The cholinergic and GABA-ergic modulation of SC affecting REM sleep may be involved in REM sleep associated visuo-spatial learning and memory consolidation, which however, need to be confirmed. Furthermore, the results suggest involvement of efferent from SC in modulation of sleep-waking via the brainstem sleep regulating areas.

17.3 Circadian Misalignment as a Mechanism of Depression Symptom Improvement in Evening-Type Adolescents With Depressive Symptoms

An evening circadian preference is characterized by a behavioral predilection for later sleep and wake timing and is associated with higher rates of MDD. The present study aims to: 1) test the effectiveness of a cognitive-behavioral sleep intervention (Transdiagnostic Sleep and Circadian Intervention; TranS-C) in a sample of adolescents with an evening circadian preference and MDD; and 2) evaluate improved alignment between circadian biology and sleep-wake behavior as a potential mechanism in the relationship between sleep and depression symptom improvement.

Regulation of wakefulness by astrocytes in the lateral hypothalamus

The lateral hypothalamus (LH) is an important brain region mediating sleep–wake behavior. Recent evidence has shown that astrocytes in central nervous system modulate the activity of adjacent neurons and participate in several physiological functions. However, the role of LH astrocytes in sleep–wake regulation remains unclear. Here, using synchronous recording of electroencephalogram/electromyogram in mice and calcium signals in LH astrocytes, we show that the activity of LH astrocytes is significantly increased during non-rapid eye movement (NREM) sleep-to-wake transitions and decreased during Wake-to-NREM sleep transitions. Chemogenetic activation of LH astrocytes potently promotes wakefulness and maintains long-term arousal, while chemogenetic inhibition of LH astrocytes decreases the total amount of wakefulness in mice. Moreover, by combining chemogenetics with fiber photometry, we show that activation of LH astrocytes significantly increases the calcium signals of adjacent neurons, especially among GABAergic neurons. Taken together, our results clearly illustrate that LH astrocytes are a key neural substrate regulating wakefulness and encode this behavior through surrounding GABAergic neurons. Our findings raise the possibility that overactivity of LH astrocytes may be an underlying mechanism of clinical sleep disorders.

Regulation of wakefulness by GABAergic dorsal raphe nucleus-ventral tegmental area pathway.

The dorsal raphe nucleus (DRN) has previously been proved to be involved in the regulation of the sleep-wake behavior. DRN contains several neuron types, such as 5-HTergic and GABAergic neurons. GABAergic neurons, which are the second largest cell subtype in the DRN, participate in a variety of neurophysiological functions. However, their role in sleep-wake regulation and the underlying neural circuitry remains unclear. Herein, we used fiber photometry and synchronous electroencephalogram (EEG)/electromyography (EMG) recording to demonstrate that DRN GABAergic neurons exhibit high activities during wakefulness and low activities during NREM sleep. Short-term optogenetic activation of DRN GABAergic neurons reduced the latency of NREM-to-wake transition and increased the probability of wakefulness, while long-term optogenetic activation of these neurons significantly increased the amount of wakefulness. Chemogenetic activation of DRN GABAergic neurons increased wakefulness for almost 2 h and maintained long-lasting arousal. In addition, inhibition of DRN GABAergic neurons with chemogenetics caused a reduction in the amount of wakefulness. Finally, similar to the effects of activating the soma of DRN GABAergic neurons, optogenetic stimulation of their terminals in the ventral tegmental area (VTA) induced instant arousal and promoted wakefulness. Taken together, our results illustrated that DRN GABAergic neurons are vital to the induction and maintenance of wakefulness, which promote wakefulness through the GABAergic DRN-VTA pathway.

Relationships between rest-activity rhythms, sleep, and clinical symptoms in individuals at clinical high risk for psychosis and healthy comparison subjects

Sleep-wake disturbances in individuals at clinical high risk (CHR) of psychosis may relate to increased symptom severity and contribute to disease progression. Here, we examined differences in rest-activity rhythms (RAR) measures, derived from actigraphy, and objective sleep outcomes, derived from electroencephalography (EEG), between 12 CHR and 16 healthy comparison (HC) individuals. Further, we examined the relationships between RAR disturbances, objective sleep outcomes and clinical psychosis symptoms (i.e., negative, positive, disorganized, general symptoms). Sleep-wake behaviors were monitored via actigraphy for 3–7 days (CHR: 5.7 ± 1.7 days; HC: 6.3 ± 1.2 days) prior to participants spending a night in the sleep laboratory, which was monitored with EEG. Separate regressions were used to examine the effect of clinical group on RAR measures and objective sleep outcomes after controlling for age and gender. CHR participants were found to be less active, specifically during the evening (17:00–20:00; β = 1.145, SE = 0.362, p = .004) and nighttime (21:00–24:00; β = 1.152, SE = 0.326, p = .002) relative to HC. Further, CHR participants had more fragmented sleep (wake after sleep onset: β = 0.888, SE = 0.395, p = .034) and more hyperarousal during sleep (NREM gamma activity: β = 1.087, SE = 0.348, p = .005), but these sleep disturbances were not related to reduced activity or clinical symptoms, whereas lower nighttime activity was related to more disorganized symptoms (ρ = −.640, p = .025). Thus, increasing activity through behavioral interventions may have additional beneficial effects on CHR clinical symptoms.

The Impact of Sleep-Wake Behaviour on Tennis Match Performance in Junior State Grade Tennis Players

PurposeTo date, no study has investigated the extent to which sleep-wake behaviour (SWB) influences match performance in junior tennis players. This study aimed to assess the influence of SWB for the week and night before on match performance, particularly match analytics and activity.MethodsThis study recruited 10 junior state grade tennis players who wore an actigraphy device and completed a sleep diary for the week before their match on two separate occasions throughout their competition season. Players wore a global positioning system device to track their movement during matches, and an experienced tennis coach recorded players' match analytics.ResultsThis study showed that the sleep fragmentation index was significantly lower the week before matches in females who had won than those who had lost. Additionally, the sleep fragmentation index was significantly lower the night before a given match than the week before. Only sleep fragmentation index and sleep latency significantly influenced match performance in junior tennis players. The percentage of second serves points won differed between match wins and losses for male players, while winners and forced errors differed for female players.ConclusionThese findings provide a detailed profile of tennis match play in junior state grade players. Despite individual differences, reduced restlessness the night before a match coincides with increased match performance.

Endogenous circadian temperature rhythms relate to adolescents' daytime physical activity.

Circadian rhythms relate to multiple aspects of health and wellbeing, including physical activity patterns. Susceptible circadian regulation predisposes to circadian misalignment, poor sleep, sleep deprivation, increased sleepiness, and thereby sedentary behavior. Adolescents’ circadian regulation is particularly vulnerable, and may lead to sedentary behavior. To investigate which factors associate strongest between physical activity (PA) and circadian behavior, we conducted multimodal circadian rhythm analyses. We investigate how individual characteristics of habitual circadian patterns associate with objectively measured PA. We studied 312 adolescents [70% females) (56% with delayed sleep phase (DSP)], mean age 16.9 years. Circadian period length, temperature mesor (estimated 24 h midline) and amplitude (difference between mesor and peak) were measured using distally attached thermologgers (ibutton 1922L, 3-day-measurement). We additionally utilized algorithm-formed clusters of circadian rhythmicity. Sleep duration, timing, DSP, and PA were measured using actigraphs (GeneActiv Original, 10-day-measurement). We found that continuous circadian period length was not associated with PA, but lower mesor and higher amplitude were consistently associated with higher levels of PA as indicated by mean Metabolic Equivalent (METmean) and moderate-to-vigorous PA (MVPA), even when controlling for sleep duration. Separate circadian clusters formed by an algorithm also reflected distinct patterns of PA accordingly. Late sleepers and those with DSP were less likely to engage in MVPA compared to non-DSP and had more sedentary behavior. Adolescents who engage in higher levels or high-intensity PA have better circadian regulation, as measured by different objective methods including distal temperature measurements as well as actigraphy-measured sleep-wake behavior.

Tick-borne encephalitis affects sleep–wake behavior and locomotion in infant rats

Background/AimsTick-borne encephalitis (TBE) is a disease affecting the central nervous system. Over the last decade, the incidence of TBE has steadily increased in Europe and Asia despite the availably of effective vaccines. Up to 50% of patients after TBE suffer from post-encephalitic syndrome that may develop into long-lasting morbidity. Altered sleep–wake functions have been reported by patients after TBE. The mechanisms causing these disorders in TBE are largely unknown to date. As a first step toward a better understanding of the pathology of TBEV-inducing sleep dysfunctions, we assessed parameters of sleep structure in an established infant rat model of TBE.Methods13-day old Wistar rats were infected with 1 × 106 FFU Langat virus (LGTV). On day 4, 9, and 21 post infection, Rotarod (balance and motor coordination) and open field tests (general locomotor activity) were performed and brains from representative animals were collected in each subgroup. On day 28 the animals were implanted with a telemetric EEG/EMG system. Sleep recording was continuously performed for 24 consecutive hours starting at day 38 post infection and visually scored for Wake, NREM, and REM in 4 s epochs.ResultsAs a novelty of this study, infected animals showed a significant larger percentage of time spend awake during the dark phase and less NREM and REM compared to the control animals (p < 0.01 for all comparisons). Furthermore, it was seen, that during the dark phase the wake bout length in infected animals was prolonged (p = 0.043) and the fragmentation index decreased (p = 0.0085) in comparison to the control animals. LGTV-infected animals additionally showed a reduced rotarod performance ability at day 4 (p = 0.0011) and day 9 (p = 0.0055) and day 21 (p = 0.0037). A lower locomotor activity was also seen at day 4 (p = 0.0196) and day 9 (p = 0.0473).ConclusionOur data show that experimental TBE in infant rats affects sleep–wake behavior, leads to decreased spontaneous locomotor activity, and impaired moto-coordinative function.

The Nucleus Accumbens CRH-CRHR1 System Mediates Early-Life Stress-Induced Sleep Disturbance and Dendritic Atrophy in the Adult Mouse.

Adverse experiences in early life have long-lasting negative impacts on behavior and the brain in adulthood, one of which is sleep disturbance. As the corticotropin-releasing hormone (CRH)-corticotropin-releasing hormone receptor 1 (CRHR1) system and nucleus accumbens (NAc) play important roles in both stress responses and sleep-wake regulation, in this study we investigated whether the NAc CRH-CRHR1 system mediates early-life stress-induced abnormalities in sleep-wake behavior in adult mice. Using the limited nesting and bedding material paradigm from postnatal days 2 to 9, we found that early-life stress disrupted sleep-wake behaviors during adulthood, including increased wakefulness and decreased non-rapid eye movement (NREM) sleep time during the dark period and increased rapid eye movement (REM) sleep time during the light period. The stress-induced sleep disturbances were accompanied by dendritic atrophy in the NAc and both were largely reversed by daily systemic administration of the CRHR1 antagonist antalarmin during stress exposure. Importantly, Crh overexpression in the NAc reproduced the effects of early-life stress on sleep-wake behavior and NAc morphology, whereas NAc Crhr1 knockdown reversed these effects (including increased wakefulness and reduced NREM sleep in the dark period and NAc dendritic atrophy). Together, our findings demonstrate the negative influence of early-life stress on sleep architecture and the structural plasticity of the NAc, and highlight the critical role of the NAc CRH-CRHR1 system in modulating these negative outcomes evoked by early-life stress.

Revisiting the Concept of Vigilance.

Vigilance deficits can be observed after a period of prolonged, continuous wakefulness. In this context there has been extensive research targeting the impact of sleep deficits on different aspects of vigilance, but the underlying concept of vigilance was hardly ever addressed and discussed. One reason for this shortcoming is the unclear and ambiguous definition of the term vigilance, which is commonly used interchangeably with sustained attention and even wakefulness. This confusion is the result of a wide range of misleading definitions, starting in the 1940s, as psychologists redefined the concept of vigilance suggested by British Neurologist, Henry Head, in 1923. Nevertheless, the concept of vigilance is still useful and innovative, especially in treating sleep problems in children and young adults. This paper reviews the current usage of the term vigilance in sleep-wake-research and describes not only the benefits, but even more clearly, its limitations. By re-focusing on the definitions given by Henry Head, the concept of vigilance is an innovative way to gather new insights into the interplay between sleep– and daytime behaviors. In addition, future research on vigilance should consider three perspectives: 1st vigilance perceived as a process to allocate resources, 2nd vigilance associated with compensatory behaviors and 3rd the role of vigilance in human environmental interactions. This approach, understood as a conceptual framework, provides new perspectives by targeting sleep-wake behaviors as a ‘real life’ outcome measure, reflecting both physical and cognitive performance as well as sleep quality and quantity.

0046 Circadian misalignment is associated with Covid-19 infection

IntroductionSleep disturbances are frequently reported in patients infected by Covid-19, but the role of sleep-wake behaviors as a risk factor to contract Covid-19 has up to now poorly been studied. The aim of this study was to explore the relationship between usual sleep-wake behaviors and the risk of Covid-19 infection in a population of subjects suspect of contact or infection with SARS-CoV-2.MethodsCross-sectionnal monocentric study set during a non-confined period in winter 2021. Recruitment took place in a Covid-19 ambulatory screening platform. Subjects between 18 and 45 years old were included whether they were symptomatic or not, healthcare workers or not, in contact with a Covid-19 case or not. They were asked about their usual sleep-wake behaviors. Usual sleep duration and sleep timing were explored during workdays and free days. Circadian misalignment was defined as at least 2 hours shift of circadian alignment (defined as the difference between mid‐sleep during workdays and mid‐sleep during free days, mid sleep as the middle between bedtime and getting up time).ResultsOne thousand eighteen subjects were included in our study (acceptance rate: 10.8%, 39% of men, mean age of 28±8). Habitual mean sleep duration was equivalent in both groups (7h47 vs 7h49, p=0.733). Circadian misalignment greater than 2 hours concerned 33% of subjects in the Covid-19 group versus 20% of the control group (p=0.026). After adjustment on age, gender, BMI and work schedules, subjects presenting a circadian misalignment superior to 2 hours had 2.07 more chances to be tested positive than subjects which respected on identical sleep-wake timing between workdays and free days (OR=2.07, 95%CI= [1.12-3.80], p=0.024).ConclusionAltered sleep not only is present in subjects infected by Covid-19 but could be responsible of a higher change to be infected. Chronobiological impact on immune system and higher chances to be exposed to social contacts could explain our findings which deserve to be confirmed through a future large cohort study. Ultimately regular sleep-wake pattern could constitute a privileged prevention target to fight Covid-19 infection.Support (If Any)

0302 Recovery Sleep in University Students

Abstract Introduction Poor sleep hygiene is common in American college students, with the majority reporting insufficient sleep. Previous studies suggest that many students extend sleep during the weekend to recover sleep debt accrued during the week. In the current study we objectively measured sleep to determine if weekend catch-up sleep was practiced. We also provided students with a 9h sleep opportunity in order to observe how an extended sleep period affected sleep architecture. Methods Students (N=36, 20 women, 19.9±1.7 years) participated in the study from September 2019-March 2020. Sleep-wake behavior was assessed for two weeks using wrist actigraphy and a twice-daily diary. During this two-week period, participants wore at-home polysomnography (PSG) on two non-consecutive nights. For these two nights, in counterbalanced order, participants were instructed to follow their typical sleep pattern or to extend their sleep opportunity to 9h. Within-subjects ANOVA were used to compare sleep between week (Sunday-Thursday) and weekend (Friday and Saturday) nights as well as between typical and 9h PSG nights. Results Compared to week nights, participants went to bed 35 minutes later and woke up 58 minutes later on weekend nights (ps&amp;lt;0.01). Measures of sleep duration and sleep continuity were comparable (ps&amp;gt;0.10) between week and weekend nights and indicated that students averaged less than 7h of sleep per night (6.3±1.0h on week nights and 6.7±1.1h on weekend nights). Self-report measures of sleep quality and daytime sleepiness were also comparable between week and weekend nights (ps&amp;gt;0.05). When instructed to extend their sleep opportunity to 9h, participants exhibited high adherence and increased total sleep time by 88 minutes compared to the typical night (p&amp;lt;0.05). This increase in sleep was due to significant increases in time spent in all four stages of sleep (NREM S1-3 and REM sleep, ps&amp;lt;0.05). Conclusion In this study, students did not utilize weekend nights to extend sleep in order to recover accumulated sleep debt from the week. When provided with a 9h sleep opportunity, participants were physically able to extend sleep and exhibited high quality sleep, suggesting that the primary driver of insufficient sleep in this population is a lack of sleep opportunity rather than impaired sleep ability. Support (If Any)

0137 Phase response curve for effects of school start times on students’ diurnal learning rhythm

Abstract Introduction School start times impose constraints on sleep-wake behaviour that can result in social jet lag. Here, we used university archived datasets (1) to test whether social jet lag was associated with lower grades, and (2) to assess the phase resetting effects of school start times on students’ diurnal learning behaviour. Methods Social jet lag was estimated in 33,645 university students by measuring the phase shift in their Learning Management System (LMS) login rhythm on school days relative to non-school days (LMS social jet lag). ANCOVA was used to test the association between LMS social jet lag and grade point average, adjusting for demographic variables. We constructed a phase response curve by plotting phase shifts on school days (LMS social jet lag) against the initial phase when students’ first class of the day took place. The initial phase was expressed relative to students’ LMS login rhythm on non-school days (LMS chronotype). Results Students with greater LMS social jet lag had a lower grade point average (ANCOVA: F9,32269 = 44.8, P &amp;lt; 0.001). Social jet lag was larger in students with a later LMS login rhythm on non-school days (later chronotype) and for earlier school start times. The phase response curve revealed that the direction and magnitude of social jet lag were strongly dependent on the phase of students’ diurnal rhythm when their first class of the day took place. Phase shifts of up to 12 h were observed when school start times occurred out of phase with students’ diurnal rhythm. Conclusion School start times have a profound impact on students’ diurnal behaviour. Students whose diurnal patterns of LMS logins were similar on both school days and non-school days obtained better grades than their peers with LMS social jet lag. Universities can potentially improve learning by scheduling classes at times that are better aligned with students’ diurnal learning rhythm. Support (If Any) Data storage and management were supported by the NUS Office of the Senior Deputy President &amp; Provost and ALSET. The work was funded by the Ministry of Education, Singapore (MOE2019-T2-2-074) and the National Research Foundation, Singapore (NRF2016-SOL002-001).

0007 Temporal Associations Between Actigraphy-Measured Daytime Movement Behaviors and Daytime Sleep in Early Childhood

Abstract Introduction Although napping in early childhood is associated with some cognitive and behavioral outcomes, less is known about relations with physical health measures. Lower levels of sedentary behavior and higher levels of physical activity have been beneficially associated with sleep measures in adults. Studies exploring sleep and daytime movement behaviors (sedentary time and physical activity) in young children have had inconsistent results and primarily focused on overnight sleep. The purpose of this micro-longitudinal analysis was to determine if: 1) daytime movement behaviors predicted the likelihood of napping the next day, 2) daytime movement behaviors predicted next-day nap duration, and 3) the occurrence of a nap predicted next-day movement behaviors. Methods In 240 children (age=50.8±9.8 months, 49.2% female) sedentary time (% of wake time), total physical activity (counts/min), and nap duration (min) were derived from wrist-based actigraphy (mean = 9.7 days), and occurrence of a nap was recorded daily. Multilevel logistic and linear models with lagged effects were used to examine temporal within-person relations between wake behaviors and nap sleep, and adjusted for night’s sleep duration of nights between days of interest (min), age (months), sex (male or female), and socioeconomic status (index). Preliminary models included interactions with nap habituality (rarely, sometimes, or frequent). Results Occurrence of a nap was not associated with next-day wake behaviors and previous-day wake behaviors did not predict nap duration. However, on days children napped, they were less sedentary (B=-2.09, p&amp;lt;0.001) and more active (B=25.8, p&amp;lt;0.001) the following day. Nap habituality did not moderate these associations. Conclusion Bidirectional associations between nap sleep and daytime wake behaviors were not evident. While daytime movement behaviors were not predictive of nap sleep, napping was beneficially associated with subsequent-day movement behaviors in preschool children. Further studies could explore specific nap sleep metrics in samples with more diverse sleep health, as well as consider the reason for daytime napping. Support (If Any) NIH R01 HL111695

Sleep Behavior and Self-Reported Infertility: A Cross-Sectional Analysis Among U.S. Women.

ObjectiveTo investigate the associations between sleep behaviors and female infertility.MethodsWe conducted a cross-sectional study composed of 2175 U.S. women 18-44 years of age from the National Health and Nutrition Examination Survey (NHANES) (2015-2018). Bedtime/waketime and sleep duration were extracted from the sleep disorder questionnaire. Self-reported infertility was defined as a binary variable based on the participants’ response to the question, “Have you ever attempted to become pregnant over a period of at least a year without becoming pregnant?”. Multivariate logistic regression analyses were done to explore the relationship between sleep behaviors and female infertility.ResultsBedtime (OR=1.24; 95% CI, 1.10-1.40, P = 0.001) and waketime (OR=1.14; 95% CI, 1.01-1.28, P = 0.037) were associated with infertility. Waketime of 08:00 was the inflection point, above which the probability of infertility increased rapidly (OR=1.41; 95% CI, 1.11-1.79, P = 0.004). Sleep-wake behavior was significantly associated with infertility (OR=1.34; 95% CI, 1.16-1.53, P < 0.001) and participants with early-bed/early-rise behavior had the lowest risk.ConclusionsAmong U.S. women 18-44 years of age, bedtime and waketime were significantly linearly and non-linearly correlated with infertility, respectively. Early-bed/early-rise behavior was associated with the lowest infertility rate. Further study is needed because the timing of sleep behaviors are modifiable factors and could be a novel strategy to cope with infertility.

Sleep disturbances, circadian activity, and nocturnal light exposure characterize high risk for and current depression in adolescence

Major depressive disorder (MDD) in adolescence is associated with irregularities in circadian rhythms and sleep. The characterization of such impairment may be critical to design effective interventions to prevent development of depression among adolescents. This study aimed to examine self-reported and actimetry-based circadian rhythms and sleep-wake behavior associated with current MDD and high risk (HR) for MDD among adolescents. Ninety-six adolescents who took part in the IDEA-RiSCo study were recruited using an empirically developed depression-risk stratification method: 26 classified as low risk (LR), 31 as HR, and 39 as a current depressive episode (MDD). We collected self-report data on insomnia, chronotype, sleep schedule, sleep hygiene as well as objective data on sleep, rest-activity, and light exposure rhythms using actimetry for 10 days. Adolescents with MDD exhibited more severe insomnia, shorter sleep duration, higher social jetlag (SJL), lower relative amplitude (RA) of activity, and higher exposure to artificial light at night (ALAN) compared with the other groups. They also presented poorer sleep hygiene compared with the LR group. The HR group also showed higher insomnia, lower RA, higher exposure to ALAN, and higher SJL compared with the LR group. HR adolescents shared sleep and rhythm alterations with the MDD group, which may constitute early signs of depression, suggesting that preventive strategies targeting sleep should be examined in future studies. Furthermore, we highlight that actimetry-based parameters of motor activity (particularly RA) and light exposure are promising constructs to be explored as tools for assessment of depression in adolescence.

Free Day, but Not Work Day, Sleep Duration Is Inversely Associated With Aortic Stiffness in Apparently Healthy Young Adults

Insufficiency or irregularity in sleep is associated with high blood pressure (BP) and aortic stiffness, both of which are independent predictors of all‐cause and cardiovascular mortality. The cardiovascular ramifications of short and irregular sleep are well documented in shift workers, but the health implications of possible differences between sleep duration on workdays (WD) and free days (FD) in non‐shift workers is less clear.PURPOSEWe sought to examine associations between WD and FD sleep duration, and then to inspect for relationships between WD and FD sleep duration, as well as the difference between WD and FD sleep duration (i.e., sleep irregularity), with BP and indices of arterial stiffness in apparently healthy young adults. We hypothesized 1) participants would sleep less on WD than FD, and 2) that participants with short WD sleep duration would exhibit higher BP and arterial stiffness, and 3) those with greater sleep irregularity would exhibit higher BP and arterial stiffness.METHODS16 apparently healthy young adults (21.8±4.0 yrs; 24.4±2.9 kg/m2; Mean±SD) participated in this study. All participants completed the Munich ChronoType Questionnaire to assess self‐described WD and FD sleep‐wake behavior. WD and FD sleep duration were determined, and sleep irregularity was quantified as the absolute value of the difference between WD and FD sleep duration. Following 10‐min of supine rest, we used an automated oscillometric device (SphygmoCor XCEL) to measure BP and augmentation index (AIx), an indirect measure of arterial stiffness. Aortic stiffness was then assessed using carotid‐femoral pulse wave velocity (cf‐PWV). WD and FD sleep duration were compared using a paired t‐test and associations between sleep with BP and indices of arterial stiffness were assessed using Pearson correlations, or the non‐parametric equivalent for sleep irregularity.RESULTSWD sleep duration was 492±85 min, FD sleep duration was 480±83 min, and sleep irregularity was 53±49 min. Systolic BP was 120±10 mmHg, diastolic BP was 68±7 mmHg, AIx was 10.9±9.8 %, and cf‐PWV was 5.8±0.7 m/s. WD sleep duration was significantly greater (P&lt;0.01) than FD sleep duration, and WD sleep duration was not associated (P&gt;0.05) with systolic BP (r=0.10), diastolic BP (r=0.10), AIx (r=0.07), or cf‐PWV (r=‐0.18). FD sleep duration was inversely correlated with cf‐PWV (r=‐0.65; P=0.01), but was not associated (P&gt;0.05) with systolic BP (r=‐0.12), diastolic BP (r =‐0.08), or AIx (r=0.25). Sleep irregularity was not associated (P&gt;0.05) with systolic BP (r=0.37), diastolic BP (r=0.45), AIx (r=0.08), or cf‐PWV (r=0.14).CONCLUSIONSContrary to our hypothesis, FD, but not WD, sleep duration was associated with aortic stiffness in apparently healthy young adults. Average sleep duration of our cohort exceeded the recommended minimum of 7 hours per night and sleep irregularity was small (i.e., &lt;60 min on average), thus potentially masking elevations in BP and arterial stiffness seen with short and/or irregular sleep such as in shift workers.

Sepsis triggered oxidative stress-inflammatory axis: the pathobiology of reprogramming in the normal sleep-wake cycle.

In individuals with sepsis-related neurodegenerative illness, sleep and circadian rhythm disturbance are common. The alteration in genomic expression linked with the immune-directed oxidative stress-inflammatory axis is thought to cause these individuals' abnormal sleep. On the other hand, sleep is linked to normal brain activity through common neurotransmitter systems and regulatory mechanisms. Ailments (ranging from cognitive to metabolic abnormalities) are seldom related to aberrant sleep that is made worse by sleep disturbance, which throws off the body's sleep-wake cycle. PubMed/Springer link /Public library of science/ScienceDirect/ Mendeley/Medline and Google Scholar were used to find possibly relevant studies. For the literature search, many keywords were considered, both individually and in combination. 'Sepsis,' 'Epidemiology of sepsis,' 'Sepsis-related hyper inflammation,' 'Relationship of sepsis-associated clock gene expression and relationship of inflammation with the reprogramming of genetic alterations' were some of the key terms utilized in the literature search. Our main objective is to understand better how traumatic infections during sepsis affect CNS processes, particularly sleep, by investigating the pathobiology of circadian reprogramming associated with immune-directed oxidative stress-inflammatory pathway responsive gene expression and sleep-wake behaviour in this study.

Roles of Neuropeptides in Sleep-Wake Regulation.

Sleep and wakefulness are basic behavioral states that require coordination between several brain regions, and they involve multiple neurochemical systems, including neuropeptides. Neuropeptides are a group of peptides produced by neurons and neuroendocrine cells of the central nervous system. Like traditional neurotransmitters, neuropeptides can bind to specific surface receptors and subsequently regulate neuronal activities. For example, orexin is a crucial component for the maintenance of wakefulness and the suppression of rapid eye movement (REM) sleep. In addition to orexin, melanin-concentrating hormone, and galanin may promote REM sleep. These results suggest that neuropeptides play an important role in sleep–wake regulation. These neuropeptides can be divided into three categories according to their effects on sleep–wake behaviors in rodents and humans. (i) Galanin, melanin-concentrating hormone, and vasoactive intestinal polypeptide are sleep-promoting peptides. It is also noticeable that vasoactive intestinal polypeptide particularly increases REM sleep. (ii) Orexin and neuropeptide S have been shown to induce wakefulness. (iii) Neuropeptide Y and substance P may have a bidirectional function as they can produce both arousal and sleep-inducing effects. This review will introduce the distribution of various neuropeptides in the brain and summarize the roles of different neuropeptides in sleep–wake regulation. We aim to lay the foundation for future studies to uncover the mechanisms that underlie the initiation, maintenance, and end of sleep–wake states.