Weekday Sleep Research Articles

Sleep, Circadian Rhythms, and Risk Across Health Domains in Adolescents With an Evening Circadian Preference

Sleep and circadian rhythm changes during adolescence contribute to increased risk across emotional, behavioral, cognitive, social, and physical health domains. This study examines if sleep and dim light melatonin onset (DLMO) are related to greater risk in these 5 health domains. Participants were 163 (93 female, age = 14.7 years) adolescents with an evening circadian preference from a study funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development. Sleep and circadian measures included weekday total sleep time (TST), bedtime, and shut-eye time assessed via sleep diary, the Children’s Morningness–Eveningness Preferences scale, and DLMO. Health domains included self-reported emotional, cognitive, behavioral, social, and physical health. Later DLMO was significantly associated with shorter weekday TST, later weekday bedtime, and later weekday shut-eye time, as well as lower risk in the behavioral domain. At the trend level, later DLMO was related to fewer physical health problems. Earlier DLMO combined with a later bedtime, later shut-eye time, or shorter TST predicted greater risk in the cognitive domain. Later DLMO and shorter TST or a later bedtime predicted worse physical health. DLMO timing was not related to the emotional or social domain. There is evidence that a discrepancy between sleep behaviors and the endogenous circadian rhythm may be related to risk in the cognitive domain for adolescents with an evening circadian preference. Preliminary evidence also indicated that a delayed DLMO and shorter TST or a later bedtime may be related to vulnerability to physical health risk.

Impact of Sleep Duration and Weekend Oversleep on Body Weight and Blood Pressure in Adolescents.

Weekend oversleep or catchup sleep is a frequent occurrence in children, but there are relatively little data concerning its impact on weight and blood pressure. The aim of this study was to assess the association between sleep duration and oversleep, and weight and blood pressure in adolescents. Sleep duration, weight and blood pressure of 327 children (51.4% boys, mean age 13.3 ± 1.7 years) who had polysomnograms performed during both exam cycles of the Tucson Children's Assessment of Sleep Apnea study (TuCASA) were analyzed. Sleep duration on school nights and non-school nights was used to compute a weighted average of child and parent reported overall sleep duration respectively. Oversleep was defined as the difference between self and parent reported weekend sleep and weekday sleep separately. Simple correlations between overall sleep duration, sleep on school and non-school nights and oversleep, and blood pressure, standardized body mass index (BMI), snoring, respiratory disturbance index (RDI) and age were calculated. Significant bivariate associations then were used to develop multivariate partial correlation models. Unadjusted negative correlations with BMI were noted for parent reported total sleep duration at the 1st exam cycle, parent and child reported total sleep and school night sleep duration, and parent reported non-school night sleep duration at the 2nd exam cycle. Additionally, for BMI, positive correlations were observed for log RDI at both exam cycles and snoring at the 2nd exam cycle. For blood pressure, there were positive associations with age, parent reported oversleep, caffeine consumption and snoring. Additionally, for blood pressure, negative relationships were observed with parent reported total sleep duration at the 1st exam cycle, and parent and child reported total sleep and school night sleep durations at the 2nd exam cycle. Partial correlations found that BMI was negatively correlated with parent reported total sleep duration at the 1st exam cycle and parent reported total sleep duration at the 2nd exam cycle, and positively correlated with snoring and log RDI at both exam cycles. Systolic blood pressure was only associated with age and snoring. Diastolic blood pressure was positively correlated with age and caffeine consumption, and negatively correlated with parent reported total and school night sleep duration. Oversleep and child reported sleep duration were not represented in any of these models. Lower amounts of sleep especially on school nights is associated with higher body weight and blood pressure. Oversleep was not associated with either body weight or blood pressure.

Pathway-based analysis of genome-wide association study of circadian phenotypes.

Sleepiness affects normal social life, which attracts more and more attention. Circadian phenotypes contribute to obvious individual differences in susceptibility to sleepiness. We aimed to identify candidate single nucleotide polymorphisms (SNPs) which may cause circadian phenotypes, elucidate the potential mechanisms, and generate corresponding SNP-gene-pathways. A genome-wide association studies (GWAS) dataset of circadian phenotypes was utilized in the study. Then, the Identify Candidate Causal SNPs and Pathways analysis was employed to the GWAS dataset after quality control filters. Furthermore, genotype-phenotype association analysis was performed with HapMap database. Four SNPs in three different genes were determined to correlate with usual weekday bedtime, totally providing seven hypothetical mechanisms. Eleven SNPs in six genes were identified to correlate with usual weekday sleep duration, which provided six hypothetical pathways. Our results demonstrated that fifteen candidate SNPs in eight genes played vital roles in six hypothetical pathways implicated in usual weekday bedtime and six potential pathways involved in usual weekday sleep duration.

청소년의 규칙적 아침식사를 위한 수면 관련 요인 분석

PurposeBreakfast is the most important meal to provide energy for the day. Breakfast is especially important to give enough nutritional support to children and adolescents for their physical growth and sexual development. Sleep-related factors like average sleep duration and wake up time would mostly be associated with regular breakfast. This study aimed to investigate the effect of sleep on regular breakfast consumption in Korean adolescents. MethodsThe study used the data from the 12th Korea Youth Risk Behavior Web-based Survey (KYRBS-XII) conducted in 2016 by the Korea Centers for Disease Control and Prevention. The data of 62,820 subjects (middle/high school students) were included in the final analysis. The study examined the factors related to regular breakfast, focusing on weekday average sleep duration and wake up time of middle school students and high school students, respectively. ResultsRegular breakfast consumption was shown to have a statistically significant association with high economic status, nutritional education, weekday average sleep duration, wake up time, and subjective sleep satisfaction in the multivariate logistic regression. Regardless of the school level, regular breakfast consumption was significantly associated with early wake up time. As to the effect of weekday average sleep duration on regular breakfast consumption, it showed some different results depending on the school level. ConclusionRegular breakfast consumption of Korean adolescents was related to weekday average sleep duration and wake up time. Having breakfast regularly was affected by both adequate weekday average sleep duration and early wake up time.

Relationship between absenteeism/presenteeism and weekday sleep debt in government employees of a Japanese city

Relationship between absenteeism/presenteeism and weekday sleep debt in government employees of a Japanese city

Sleep characteristics associated with drowsy driving

ObjectiveThe aim of this study was to evaluate sleep characteristics associated with drowsy driving in an adult population. MethodsThe study subjects consisted of 1675 adults aged 19 years or older who completed a population-based questionnaire survey on sleep habits. Experiences of drowsy driving were obtained from self-reported data. We investigated sleep-related variables including sleep duration, sleep efficiency, chronotype, subjective sleep perception, daytime sleepiness, sleep quality, and snoring. We performed multivariate logistic regression analysis to determine sleep characteristics independently associated with drowsy driving. ResultsThe mean age of the subjects was 43.2 years, and 66.3% were men. The prevalence of self-reported drowsy driving was 23.6% (396 of 1675), and 33.1% of subjects experienced dozing at the wheel at least once a month. Multivariate analysis demonstrated that men, office and manual workers, excessive daytime sleepiness, depression, habitual snoring, and perceived insufficient sleep were independently associated with drowsy driving. Subgroup analyses revealed that reduced weekday sleep duration was a risk factor of drowsy driving in adults with perceived sufficient sleep. On the other hand, frequent alcohol drinking significantly increased risk of drowsy driving in the subgroup with perceived sleep insufficiency. Furthermore, ordinal regression analyses confirmed the association between sleep characteristics and drowsy driving across different drowsy driving frequencies. ConclusionExcessive daytime sleepiness, depression, habitual snoring, and perceived insufficient sleep were sleep-related risk factors for drowsy driving. In addition to maintaining healthy sleep habits, individuals at high risk should be encouraged to evaluate underlying sleep disorders or psychiatric problems to prevent drowsy driving.

Verification of effect of sleep health education program in workplace: a quasi-randomized controlled trial.

Short sleep duration is a serious problem that not only enhances the risk of various mental and physical disorders, but also affects the productivity in the workplace. However, in terms of studies focused on workers, there are few reports that evaluated sleeping conditions in an objective way. The purpose of this study is to implement sleep health education in the workplace in terms of primary prevention of mental health disorder and then to investigate the subjective and objective effectiveness of the education using self-administered questionnaires (sleep duration, ESS, AIS, PHQ-9, SF-8) and an activity monitor (MTN-210). Study design is a quasi-randomized controlled trial. Sleep health education was provided through three 50-min lectures (total 150 min) as a single cycle for five months in the Intervention group. We obtained baseline data and then six months later. The study analyzed 70 subjects (36 Intervention group, 34 Control group). The weekday sleep duration for the Control group decreased by 12.9 min, whereas that of the Intervention group increased by 14.3 min (difference of 27.2 min), resulting in a significantly increase in score for the Intervention group. The present study suggests that sleep health education may be beneficial for good sleep habits in workers.

Complex childcare experiences and sleep outcomes in young children

ObjectivesAttending center-based childcare has been linked to shorter nighttime sleep in children. However, relatively little attention has been paid to the role of complexity and transition of childcare arrangements on children's sleep. This study used prospective, nationally representative data to estimate the associations between complex childcare experiences and sleep outcomes during infancy and toddlerhood. DesignProspective longitudinal study. SettingThis study used 9-month (n = 3921) and 2.5-year-old (n = 3412) data from the Longitudinal Study of Australian Children. The 2-wave longitudinal sample included 3046 children. InterventionNot applicable. MeasurementsComplex childcare experiences were measured by time spent in center, relative, and nonrelative childcare; use of multiple childcare arrangements; and patterns of childcare use over the 2-wave period. Sleep outcomes included maternal reports of weekday and weekend nighttime sleep duration, difficulty falling asleep, waking up during the night, and restless sleeping of the child. ResultsCross-sectional analysis showed that, in addition to center childcare, hours spent in relative and nonrelative childcare were negatively associated with weekday nighttime sleep duration but not weekend nighttime sleep duration. Multiple childcare arrangements were not associated with worse sleep outcomes. Longitudinal analysis showed that the association between child age and nighttime sleep duration was moderated by patterns of childcare use. Late attenders and children who used childcare for 2 waves but changed configuration had smaller increase of nighttime sleep duration. ConclusionsIn addition to center childcare, noncenter childcare may be an influential factor for children's nighttime sleep. Longitudinal patterns of childcare use can moderate children's developmental trajectories of nighttime sleep.

The effect of chronotype (morningness/eveningness) on medical students' academic achievement in Sudan.

ObjectivesThere is increasing awareness about the effects of circadian misalignment on health and work. In the present study, we aimed to investigate the effects of chronotype on academic achievement among medical students.MethodsA cross-sectional comparative study was conducted among 140 medical students (64 who averaged an A grade and 76 who averaged a C grade) completing the clinical phase at the medical college of Omdurman University, Sudan. The participants were asked to sign a written informed consent and to keep a diary detailing their bedtime, wake-up time, sleep latency, and sleep duration during working days and weekends. Then, the participants were invited to respond to a questionnaire. The chronotype was calculated from the mid-sleep time during the weekend and sleep debt. Various sleep parameters were then compared between the two groups. A t-test and logistic regression analysis were used to test the statistical significance.ResultsThe medical students with average grades were more of the evening chronotype than the students with excellent grades (p < 0.05). Significant differences were found between the two groups regarding weekend bedtime, wake-up time, and sleep duration. In addition, significant differences were evident for weekday bedtime, sleep latency, and wake-up lag between weekdays and weekends. No differences were observed between the two groups during weekday wake-up time and sleep duration, chronotype between gender, and bedtime delay between weekdays and weekends (p > 0.05).ConclusionStudents whose average grade was a C were more likely to have a later bedtimes during weekdays and weekends, sleep more during weekends, and were more evening.

Eveningness and Later Sleep Timing Are Associated with Greater Risk for Alcohol and Marijuana Use in Adolescence: Initial Findings from the National Consortium on Alcohol and Neurodevelopment in Adolescence Study.

Abundant cross-sectional evidence links eveningness (a preference for later sleep-wake timing) and increased alcohol and drug use among adolescents and young adults. However, longitudinal studies are needed to examine whether eveningness is a risk factor for subsequent alcohol and drug use, particularly during adolescence, which is marked by parallel peaks in eveningness and risk for the onset of alcohol use disorders. This study examined whether eveningness and other sleep characteristics were associated with concurrent or subsequent substance involvement in a longitudinal study of adolescents. Participants were 729 adolescents (368 females; age 12 to 21years) in the National Consortium on Alcohol and Neurodevelopment in Adolescence study. Associations between the sleep variables (circadian preference, sleep quality, daytime sleepiness, sleep timing, and sleep duration) and 3 categorical substance variables (at-risk alcohol use, alcohol bingeing, and past-year marijuana use [y/n]) were examined using ordinal and logistic regression with baseline age, sex, race, ethnicity, socioeconomic status, and psychiatric problems as covariates. At baseline, greater eveningness was associated with greater at-risk alcohol use, greater bingeing, and past-year use of marijuana. Later weekday and weekend bedtimes, but not weekday or weekend sleep duration, showed similar associations across the 3 substance outcomes at baseline. Greater baseline eveningness was also prospectively associated with greater bingeing and past-year use of marijuana at the 1-year follow-up, after covarying for baseline bingeing and marijuana use. Later baseline weekday and weekend bedtimes, and shorter baseline weekday sleep duration, were similarly associated with greater bingeing and past-year use of marijuana at the 1-year follow-up after covarying for baseline values. Findings suggest that eveningness and sleep timing may be under recognized risk factors and future areas of intervention for adolescent involvement in alcohol and marijuana that should be considered along with other previously identified sleep factors such as insomnia and insufficient sleep.

Do parents\u2019 support behaviours predict whether or not their children get sufficient sleep? A cross-sectional study

BackgroundSleep is an essential component of healthy cognitive and physical development. Lack of sleep may put children at risk for a variety of mental and physical health outcomes, including overweight, obesity and related chronic diseases. Given that children’s sleep duration has decreased in recent decades, there is a need to understand the determinants of child sleep, including the role of parental support behaviours. This study aims to determine the relative contribution of different types of parental support behaviours for predicting the likelihood that children meet recently established Canadian sleep guidelines.MethodsData were collected using Computer Assisted Telephone Interviews (CATI) of parents or guardians with at least one child under the age of 18 living in Ontario, Canada. To align with sleep guidelines, parents included in this analysis had at least one child between 5 and 17 years of age (n = 1622). Two multivariable logistic regression models were built to predict whether or not parents reported their child was meeting sleep guidelines – one for weekday sleep and another for sleep on weekends. Independent variables included parent and child age and gender, motivational and regulatory parental support behaviours, and socio-demographic characteristics.ResultsOn weekdays, enforcing rules about child bedtime was a significant positive predictor of children meeting sleep guidelines (OR: 1.59; 95% CI: 1.03–2.44); while encouraging the child to go to bed at a specific time was a significant negative predictor of child meeting sleep guidelines (OR: 0.29; 95% CI: 0.13–0.65). On weekends, none of the parental support behaviours contributed significantly to the predictions of child sleep. For both weekdays and weekends, the child’s age group was an important predictor of children meeting sleep guidelines.ConclusionsThe contribution of parental support behaviours to predictions of children meeting sleep guidelines varied with the type of support provided, and weekend versus weekday sleep. While only enforcing bedtime rules on weekdays contributed to children meeting sleep guidelines, the importance of children getting a good night’s sleep, and the capacity of parents to help them do so, should be emphasized in public health efforts promoting healthy child development.

Variable School Start Times and Middle School Student's Sleep Health and Academic Performance

PurposeImproving sleep health among adolescents is a national health priority and implementing healthy school start times (SSTs) is an important strategy to achieve these goals. This study leveraged the differences in middle school SST in a large district to evaluate associations between SST, sleep health, and academic performance. MethodsThis cross-sectional study draws data from a county-wide surveillance survey. Participants were three cohorts of eighth graders (n = 26,440). The school district is unique because SST ranged from 7:20 a.m. to 8:10 a.m. Path analysis and probit regression were used to analyze associations between SST and self-report measures of weekday sleep duration, grades, and homework controlling for demographic variables (sex, race, and socioeconomic status). The independent contributions of SST and sleep duration to academic performance were also analyzed. ResultsEarlier SST was associated with decreased sleep duration (χ2 = 173, p < .0001) and deficient sleep (≤7 hours) among 45% of students. Students with SST before 7:45 a.m. were at increased risk of decreased sleep duration, academic performance, and academic effort. Path analysis models demonstrated the independent contributions of sleep duration, SST, and variable effects for demographic variables. ConclusionsThis is the first study to evaluate the independent contributions of SST and sleep to academic performance in a large sample of middle school students. Deficient sleep was prevalent, and the earliest SST was associated with decrements in sleep and academics. These findings support the prioritization of policy initiatives to implement healthy SST for younger adolescents and highlight the importance of sleep health education disparities among race and gender groups.

School‐Based Sleep Education Programs for Short Sleep Duration in Adolescents: A Systematic Review and Meta‐Analysis

Insufficient sleep among students is a major school health problem. School-based sleep education programs tailored to reach large number of students may be one of the solutions. A systematic review and meta-analysis was conducted to summarize the programs' effectiveness and current status. Electronic databases were searched up until May 2015. Randomized controlled trials of school-based sleep intervention among 10- to 19-year-old students with outcome on total sleep duration were included. Methodological quality of the studies was assessed using the Cochrane's risk of bias assessment. Seven studies were included, involving 1876 students receiving sleep education programs and 2483 attending classes-as-usual. Four weekly 50-minute sleep education classes were most commonly provided. Methodological quality was only moderate, with a high or an uncertain risk of bias in several domains. Compared to classes-as-usual, sleep education programs produced significantly longer weekday and weekend total sleep time and better mood among students at immediate post-treatment, but the improvements were not maintained at follow-up. Limited by the small number of studies and methodological limitations, the preliminary data showed that school-based sleep education programs produced short-term benefits. Future studies should explore integrating sleep education with delayed school start time or other more effective approaches.

0814 WOULD YOU CALL YOURSELF A SHORT OR LONG SLEEPER? PERCEPTIONS OF SLEEP CATEGORY ASSOCIATED WITH REPORTED SLEEP DURATION, INSOMNIA, AND HEALTH

Short and long sleep durations are prevalent and associated with poor health. This study examined whether an individual’s self-identified sleep category (e.g., “short” or “long”) relates to observed sleep duration. The study also explored whether perceptions of sleep durations are affected by the presence of insomnia and whether self-described category predicts poor health above observed sleep duration. Data were from the Sleep and Healthy Activity, Diet, Environment, and Socialization (SHADES) Study, a community-based survey of 1,007 adults (22–60 years old). Sleep duration was assessed with the BRFSS item (sleep per 24h period) and the NHANES item (weekday nighttime sleep) for comparison purposes. Insomnia was measured with the Insomnia Severity Index. Respondents were asked whether they considered themselves a “Very-Short-Sleeper,” “Short-Sleeper,” “Average-Length-Sleeper,” “Long-Sleeper,” or “Very-Long-Sleeper.” Self-described groups were compared to groups derived from reported sleep duration (<7h=short, 7–8=normal, and >8h=long). Linear regression, adjusted for age, sex, race/ethnicity, and education, evaluated sleep duration differences across groups. Multinomial logistic regression, adjusted for covariates and sleep duration, examined whether insomnia predicts self-described group and whether self-described group predicts poor health. Overlap between derived and self-described category was modest, with only 62% of 7-8hr sleepers identifying as “average-duration.” Similarly, overlap for “short” and “long” sleep was 67% and 52%, respectively. This is in comparison to overlap between BRFSS and NHANES of 77%, 88%, and 33% for average-duration, short, and long sleep. Self-identified “very short sleepers” reported 93 fewer minutes of sleep, vs “average-duration sleepers” (p<0.0001). Similarly, “short sleepers” reported 44 minutes less (p<0.0001), “long sleepers” reported 55 more minutes (p<0.0001), and “very long sleepers” reported 101 more minutes (p<0.0001). Insomnia was positively associated with self-identifying as “very short” (B=1.19,p<0.0001), “short” (B=1.37,p<0.0001), “long” (B=1.07,p<0.0001), and “very long” (B=1.26,p<0.0001). Increased likelihood of being in poor health was associated with self-identified “very short” (OR=2.33,p<0.0001), “short” (OR=2.59,p=0.001), and “very long” (OR=3.64,p=0.006) sleep. Self-described sleep categories are associated with reported sleep duration, but imperfectly overlap with empirically-­defined categories. Insomnia may contribute to perceptions of sleep category as abnormal. Self-identified category predicted poor health above observed sleep duration. R21ES022931.

Thank god it's Friday – sleep improved

The weekend is usually seen as a window of recovery. Thus, sleep before a day off may be less impaired than that before a workday. However, very few polysomnographical studies have investigated this hypothesis. Therefore, the aim of the present study was to compare sleep before a workday with that before a weekend. Seventeen teachers participated. Sleep was recorded with polysomnography on one weekday night during the workweek, and on a workday (Friday) followed by a day off. Sleep diaries and actigraphs were also used. Weekend sleep showed delayed bedtime and time of rising, a longer total sleep time (45min), increased N3 and N1, and decreased N2 and REM. Sleep spindles were reduced. The results remained after truncation to the shortest common sleep duration (5h). The increase in N3 from weekday sleep to Friday night sleep was positively correlated with N1 change (r=0.853, P≤0.001), and negatively correlated with N2 change (r=-0.614, P≤0.001). Subjective ratings showed that weekend sleep was associated with less awakening problems and lower subjective arousal during the day. The authors concluded that weekend sleep was longer, and showed increased N3 and N1. The authors suggest that the N3 increase before the day off is a result of lower stress, while the N1 increase may be an effect of sleep spindle suppression via the increase of N3 (which would suppress sleep spindles), thus reducing N2 and enhancing N1.

Relationship between parent knowledge of child sleep, and child sleep practices and problems: A pilot study in a children's hospital cohort.

To describe parent reports of sleep practices, and examine associations with parent knowledge of child sleep, and whether children's sleep practices differ between parents who underestimated, overestimated or accurately estimated children's sleep needs. Parents of children aged 2-12 years (n = 115) attending hospital inpatient or day wards were approached and asked to report child sleep routines, sleep problems, parent education, household income and parent knowledge of child sleep via questionnaire. Younger age was associated with earlier bedtimes and wake times, shorter sleep latencies, longer sleep durations and greater sleep problems (P < 0.05). Parents from higher income homes reported earlier bedtimes and wake times, shorter sleep latencies and fewer sleep problems (P < 0.05). Parents with higher education reported shorter sleep latencies (P < 0.05). Parents with greater knowledge about child sleep reported earlier weekday and weekend bedtimes (r s ≥ 0.26) and wake times (r s ≥ 0.21) and greater consistency between their child's weekend and weekday sleep routines (P < 0.05). In comparison with parents who correctly estimated their child's sleep needs: parents who underestimated reported later weekday bedtimes (on average, 46 min), and longer sleep latencies (17 min); parents who overestimated reported longer sleep latencies (22 min). These findings remained significant when controlling for child age (P < 0.05). Parents with increased sleep knowledge, higher incomes and higher levels of education were more likely to report earlier bedtimes, wake times and more consistent sleep routines for their children.

Is insufficient sleep duration associated with suicidal behavior in Korean adolescents?

The second leading cause of death among Korean adolescents was suicide in 2014. We assessed the relationship between sleep duration and suicidal behavior (ideation, planning and attempt) using data from the Korea Youth Risk Behavior Web-based Survey (KYRBS). KYRBS is an anonymous online survey in self-reporting format that investigates the health status of middle and high school students. Weekly sleep duration was divided into six groups (more than 8, 7–8, 6–7, 5–6, 4–5 h, less than 4 h). We compared the more-than-8-h group with others for sleep duration-associated suicidal behavior. Results showed that even though the confidence interval for the odds ratio for some sleep duration groups was not significant, there was a statistically significant inverse positive trend of suicidal behavior (ideation, planning and attempt) with the sleep duration groups (P value for trend ≤0.001). In conclusion, this study found that short average weekday sleep duration among Korean adolescents was associated with suicidal behavior independent of various confounding factors, which includes depressed mood.

Short Sleep Duration and Circadian Rhythms: Association with Suicidal Behaviour

The current lifestyles in modern societies promote a behaviourally-induced sleep deprivation and circadian rhythm alterations. Some sleep disorders influence the development of suicidal behaviours. This study aims to review the literature exploring the association of both short sleep duration and sleep circadian rhythms with suicidal behaviours. A review was conducted in the PubMed database, using the query (“circadian rhythms” OR “sleep” OR “sleep disorders”) AND (“suicide” OR “suicidal behaviour” OR “suicidality”). The results were filtered for the last 10 years, with 522 results. Studies relating sleep disorders or circadian rhythms with suicidal behaviours, using a well-defined index for sleep disorders, and any measure of suicidal behaviour, were included. After the selection criteria, 48 studies were selected for qualitative analysis. An association between short sleep duration and an increased risk of suicidal behaviour was found in most of the studies with children/adolescents and adults. Particularly, studies measuring weekend vs. weekday sleep duration suggest a concrete role of behaviourally-induced sleep deprivation in this increased risk. Contrastingly, in studies with the elderly, that association was not significant. For sleep circadian rhythms, the studies point to an association between an evening-type chronotype and suicidal behaviours. The results suggest a significant association of short sleep duration and evening-type chronotype with suicidal behaviours, for youth and adults. Both sleep disorders could be connected through a behaviourally-induced sleep deprivation. These associations can provide possible fields of intervention to prevent suicide.

Neurobehavioral Impact of Successive Cycles of Sleep Restriction With and Without Naps in Adolescents.

Study Objectives:To characterize adolescents’ neurobehavioral changes during two cycles of restricted and recovery sleep and to examine the effectiveness of afternoon naps in ameliorating neurobehavioral deficits associated with multiple nights of sleep restriction.Methods:Fifty-seven healthy adolescents (aged 15–19 years; 31 males) participated in a parallel group study. They underwent two cycles of sleep restriction (5-hr time in bed [TIB] for five and three nights in the first and the second cycles, respectively; 01:00–06:00) and recovery (9-hr TIB for two nights per cycle; 23:00–08:00) intended to simulate the weekday sleep loss and weekend attempt to “catch up” on sleep. Half of the participants received a 1-hr nap opportunity at 14:00 following each sleep-restricted night, while the other half stayed awake. Sustained attention, sleepiness, speed of processing, executive function, and mood were assessed 3 times each day.Results:Participants who were not allowed to nap showed progressive decline in sustained attention that did not return to baseline after two nights of recovery sleep. Exposure to the second period of sleep restriction increased the rate of vigilance deterioration. Similar patterns were found for other neurobehavioral measures. Napping attenuated but did not eliminate performance decline. These findings contrasted with the stable performance of adolescents, given 9-hr TIB each night in our recent study.Conclusions:Adolescents’ neurobehavioral functions may not adapt to successive cycles of sleep curtailment and recovery. In sleep-restricted adolescents, weekend “catch-up sleep,” even when combined with napping during weekdays, is inferior to receiving a 9-hr sleep opportunity each night.

High School Start Times and the Impact on High School Students: What We Know, and What We Hope to Learn.

Several organizations have provided recommendations to ensure high school starts no sooner than 08:30. However, although there are plausible biological reasons to support such recommendations, published recommendations have been based largely on expert opinion and a few observational studies. We sought to perform a critical review of published evidence regarding the effect of high school start times on sleep and other relevant outcomes. We performed a broad literature search to identify 287 candidate publications for inclusion in our review, which focused on studies offering direct comparison of sleep time, academic or physical performance, behavioral health measures, or motor vehicular accidents in high school students. Where possible, outcomes were combined for meta-analysis. After application of study criteria, only 18 studies were suitable for review. Eight studies were amenable to meta-analysis for some outcomes. We found that later school start times, particularly when compared with start times more than 60 min earlier, are associated with longer weekday sleep durations, lower weekday-weekend sleep duration differences, reduced vehicular accident rates, and reduced subjective daytime sleepiness. Improvement in academic performance and behavioral issues is less established. The literature regarding effect of school start time delays on important aspects of high school life suggests some salutary effects, but often the evidence is indirect, imprecise, or derived from cohorts of convenience, making the overall quality of evidence weak or very weak. This review highlights a need for higher-quality data upon which to base important and complex public health decisions.