Sleep-wake patterns and sleep disturbance among Hong Kong Chinese adolescents

STUDY OBJECTIVES: To determine sleep-wake patterns and evaluate sleep disturbance in Hong Kong adolescents; to identify factors that are associated with sleep disturbance; and to examine the relationship of sleep-wake variables and academic performance. DESIGN AND SETTING: A school-based cross-sectional survey. PARTICIPANTS: Sample included 1629 adolescents aged 12 to 19 years. MEASUREMENTS AND RESULTS: Self-report questionnaires, including sleep-wake habit questionnaire, Sleep Quality Index, Morningness/ Eveningness scale, Epworth Sleepiness Scale, Perceived Stress Scale, academic performance, and personal data were administered. The average school-night bedtime was 23:24, and total sleep time was 7.3 hr. During weekends, the average bedtime and rise time was delayed by 64 min and 195 min, respectively. The prevalence of sleep disturbances occurring > or = 3 days per week in the preceding 3 months were: difficulty falling asleep (5.6%), waking up during the night (7.2%), and waking up too early in the morning (10.4%). The prevalence of > or = 1 of these three symptoms was 19.1%. Stepwise regression analyses revealed that circadian phase preference was the most significant predictor for school night bedtime, weekend oversleep, and daytime sleepiness. Perceived stress was the most significant risk factor for sleep disturbance. Students with marginal academic performance reported later bedtimes and shorter sleep during school nights, greater weekend delays in bedtime, and more daytime sleepiness than those with better grades. CONCLUSION: The prevalence of sleep deprivation and sleep disturbance among Hong Kong adolescents is comparable to those found in other countries. An intervention program for sleep problems in adolescents should be considered.     

Actigraphy‐assessed sleep during school and vacation periods: a naturalistic study of restricted and extended sleep opportunities in adolescents

School‐related sleep restriction in adolescents has been identified by studies comparing weekday and weekend sleep. This study compared weekday and vacation sleep to assess restricted and extended sleep opportunities. One‐hundred and forty‐six adolescents (47.3% male) aged 16.2 ± 1.0 years (M ± SD) from the general community wore an actigraph continuously for 4 weeks: the last week of a school term (Time‐E), the following 2‐week vacation, and the first week of the next term. Self‐reported sleep was assessed for each of the three time intervals, and chronotype was assessed using the Morningness–Eveningness Questionnaire at Time‐E. Daily actigraphy bedtime, rise‐time, time‐in‐bed, total sleep time, sleep onset latency, sleep efficiency, and % wake after sleep onset were analysed using latent growth curve modelling. The removal of school‐related sleep restriction was associated with an abrupt delay in sleep timing and increase in sleep duration. Subsequently, bedtime and rise‐time showed further linear delays throughout the vacation, while changes in time‐in‐bed were non‐significant. Sleep onset latency increased linearly, peaking in the middle of the second vacation week. Across the first vacation week, total sleep time and sleep efficiency linearly decreased, while % wake after sleep onset increased. These changes stabilized during the second vacation week. Older age and eveningness were associated with later bedtime and rise‐time, whilst females had longer time‐in‐bed, total sleep time and sleep onset latency. Compared with school days, sleep during the vacation was characterized by later timing, longer duration, lower quality and greater variability. Recovery from school‐related sleep restriction appeared to be completed within the 2 weeks of naturalistic extended sleep.     

Associations between sleep habits and mental health status and suicidality in a longitudinal survey of monozygotic twin adolescents

Several epidemiological studies have indicated that there is a relationship between sleep habits, such as sleep duration, bedtime and bedtime regularity, and mental health status, including depression and anxiety in adolescents. However, it is still to be clarified whether the relationship is direct cause‐and‐effect or mediated by the influence of genetic and other traits, i.e. quasi‐correlation. To examine this issue, we conducted a twin study using a total of 314 data for monozygotic twins from a longitudinal survey of sleep habits and mental health status conducted in a unified junior and senior high school (grades 7–12), located in Tokyo, Japan. Three‐level hierarchical linear model analysis showed that both bedtime and sleep duration had significant associations with the Japanese version of the 12‐item General Health Questionnaire (GHQ‐12) score, suicidal thoughts and the experience of self‐harm behaviours when genetic factors and shared environmental factors, which were completely shared between co‐twins, were controlled for. These associations were statistically significant even after controlling for bedtime regularity, which was also associated significantly with the GHQ‐12 score. These suggest that the associations between sleep habits and mental health status were still statistically significant after controlling for the influence of genetic and shared environmental factors of twins, and that there may be a direct cause‐and‐effect in the relationship in adolescents. Thus, late bedtime and short sleep duration could predict subsequent development of depression and anxiety, including suicidal or self‐injury risk. This suggests that poor mental health status in adolescents might be improved by health education and intervention concerning sleep and lifestyle habits.     

Associations between objectively measured and self‐reported sleep with academic and cognitive performance in adolescents: DADOS study

Adequate sleep has been positively related with health and school achievement outcomes during adolescence. The aim of this study was to investigate the associations of objectively measured and self‐reported sleep duration and quality with academic and cognitive performance in adolescents. This study was conducted with 257 adolescents (13.9 ± 0.3 years) from the DADOS study (Deporte, ADOlescencia y Salud). Objectively measured and self‐reported sleep duration and quality were obtained by a wrist‐worn GENEActiv accelerometer and the Spanish version of Pittsburgh Sleep Quality Index questionnaire, respectively. Academic performance was analysed through school records using four indicators: math, language, science and grade point average score. Cognitive performance was measured using the Spanish version of the “SRA Test of Educational Ability”. After Benjamini–Hochberg correction for the false discovery rate, objectively measured sleep duration was negatively associated with verbal ability (β = ?0.179, p = .004), whilst self‐reported sleep quality was positively associated with academic performance (β ranging from 0.209 to 0.273; all p < .001). These associations remained significant after further controlling for physical fitness and physical activity. Conversely, there were no associations between self‐reported sleep duration and objective sleep quality with academic and cognitive performance. Our findings fit in line with previous research showing that sleep quality may play an important role on adolescents’ academic performance. Further interventional research is needed to clarify the mechanisms by which sleep is related to academic performance in youth.     

Start Later,Sleep Later: School Start Times and Adolescent Sleep in Homeschool Versus Public/Private School Students

Homeschooled students provide a naturalistic comparison group for later/flexible school start times. This study compared sleep patterns and sleep hygiene for homeschooled students and public/private school students (grades 6–12). Public/private school students (n = 245) and homeschooled students (n = 162) completed a survey about sleep patterns and sleep hygiene. Significant school group differences were found for weekday bedtime, wake time, and total sleep time, with homeschooled students waking later and obtaining more sleep. Homeschooled students had later school start times, waking at the same time that public/private school students were starting school. Public/private school students had poorer sleep hygiene practices, reporting more homework and use of technology in the hour before bed. Regardless of school type, technology in the bedroom was associated with shorter sleep duration. Later school start times may be a potential countermeasure for insufficient sleep in adolescents. Future studies should further examine the relationship between school start times and daytime outcomes, including academic performance, mood, and health.     

Sleep patterns are associated with common illness in adolescents

This prospective, field‐based study examined the association between actigraphically measured total sleep time and incident illness including cold, flu, gastroenteritis and other common infectious diseases (e.g. strep throat) in adolescents during the course of a school semester. Participants were 56 adolescents ages 14–19 years (mean = 16.6, standard deviation = 1.2, 39% male) from five high schools in Rhode Island. Beginning in late January, adolescents wore actigraphs [mean 91 (19) days, range 16–112 days] and were assigned post‐hoc to longer or shorter sleep groups based on median splits. Adolescents were interviewed weekly across as many as 16 weeks (modal number of interviews = 13) using a structured protocol that included 14 health event questions. Illness events and illness‐related school absences were coded for 710 completed interviews, with 681 illness events and 90 school absences reported. Outcomes (illness bouts, illness duration and absences) were compared among sex, sleep and academic year groups using non‐parametric regression. In a subset of 18 subjects, mean actigraphically estimated total sleep time six nights before matched illness/wellness events was compared using multivariate analysis of variance (manova ). Longer sleepers and males reported fewer illness bouts; total sleep time effects were more apparent in males than females. A trend was found for shorter total sleep time before ill events. The present findings in this small naturalistic sample indicate that acute illnesses were more frequent in otherwise healthy adolescents with shorter sleep, and illness events were associated with less sleep during the previous week than comparable matched periods without illness.     

School start time and sleep in Canadian adolescents

Insufficient sleep is a serious problem in adolescents and school start time is thought to be a key contributor. This study provided the first comprehensive assessment of school start times across Canada and examined whether school start times were associated with sleep duration and tiredness among adolescents. We collected information on school start times from 362 schools that participated in the 2013/2014 Health Behaviour in School‐aged Children study. We calculated sleep duration from weekday bedtime and wake time reported by 29 635 students (aged 10–18 years). We classified weekday sleep as sufficient if it met national recommendations, and used data on self‐reported tiredness at school in the morning. Random‐effects regression models estimated the association of school start time with sleep duration, sleep sufficiency and tiredness. On average, schools started at 08:43 hours. Students slept an average of 8:36 h on weekdays and 69% met sleep duration recommendations, but 60% reported feeling tired in the morning. Every 10‐min delay in school start time corresponded with 3.2 [95% confidence interval (CI): 2.0, 4.5] additional minutes of sleep, a 1.6% (95% CI: 0.5, 2.8) greater probability of sufficient sleep and a 2.1% (95% CI: 1.0, 3.2) smaller probability of feeling tired at school in the morning. Students from schools that started later slept longer, were more likely to meet sleep recommendations and were less likely to report feeling tired in the morning. The study adds weight to the mounting evidence that delaying school start time benefits adolescent sleep.     

Trends in self‐reported sleep problems,tiredness and related school performance among Finnish adolescents from 1984 to 2011

The aim of this study was to investigate long‐term trends in insomnia symptoms, tiredness and school performance among Finnish adolescents. A time–series from 1984 to 2011 was analysed from two large‐scale survey studies, the Finnish School Health Promotion Study and the Health Behavior in School‐Aged Children study. A total of 1 136 583 adolescents aged 11–18 years answered a standardized questionnaire assessing frequency of insomnia symptoms, tiredness and school performance. A clear approximately twofold increasing trend in insomnia symptoms and tiredness was found from the mid‐1990s to the end of the 2000s. The increase was evident in all participating age groups and in both genders. After 2008, the increase seems to have stopped. Insomnia symptoms and tiredness were associated with lower school performance and they were more prevalent among girls (11.9 and 18.4%) compared to boys (6.9 and 9.0%, respectively). Unexpectedly, we also observed an increasingly widening gap in school performance between normally vigilant and chronically tired pupils. The underlying causes of these phenomena are unknown, but may concern changes in the broader society. The observed recent increasing trend in adolescents’ sleep problems is worrisome: poor sleep quality has also been suggested to associate with clinical or subclinical mood or anxiety disorders and behavioural problems and predispose to sleep and psychiatric disorders later in life. Our results justify further studies and call for serious attention to be paid to adolescent's sleep in the Finnish educational system and society at large.     

An approach to understanding sleep and depressed mood in adolescents: person‐centred sleep classification

Depressive mood in youth has been associated with distinct sleep dimensions, such as timing, duration and quality. To identify discrete sleep phenotypes, we applied person‐centred analysis (latent class mixture models) based on self‐reported sleep patterns and quality, and examined associations between phenotypes and mood in high‐school seniors. Students (n = 1451; mean age = 18.4 ± 0.3 years; 648 M) completed a survey near the end of high‐school. Indicators used for classification included school night bed‐ and rise‐times, differences between non‐school night and school night bed‐ and rise‐times, sleep‐onset latency, number of awakenings, naps, and sleep quality and disturbance. Mood was measured using the total score on the Center for Epidemiologic Studies‐Depression Scale. One‐way anova tested differences between phenotype for mood. Fit indexes were split between 3‐, 4‐ and 5‐phenotype solutions. For all solutions, between phenotype differences were shown for all indicators: bedtime showed the largest difference; thus, classes were labelled from earliest to latest bedtime as ‘A’ (n = 751), ‘B’ (n = 428) and ‘C’ (n = 272) in the 3‐class solution. Class B showed the lowest sleep disturbances and remained stable, whereas classes C and A each split in the 4‐ and 5‐class solutions, respectively. Associations with mood were consistent, albeit small, with class B showing the lowest scores. Person‐centred analysis identified sleep phenotypes that differed in mood, such that those with the fewest depressive symptoms had moderate sleep timing, shorter sleep‐onset latencies and fewer arousals. Sleep characteristics in these groups may add to our understanding of how sleep and depressed mood associate in teens.     

Chronic stress undermines the compensatory sleep efficiency increase in response to sleep restriction in adolescents

To investigate the effects of real‐life stress on the sleep of adolescents, we performed a repeated‐measures study on actigraphic sleep estimates and subjective measures during one regular school week, two stressful examination weeks and a week's holiday. Twenty‐four adolescents aged 17.63 ± 0.10 years (mean ± standard error of the mean) wore actigraphs and completed diaries on subjective stress, fatigue, sleep quality, number of examinations and consumption of caffeine and alcohol for 4 weeks during their final year of secondary school. The resulting almost 500 assessments were analysed using mixed‐effect models to estimate the effects of mere school attendance and additional examination stress on sleep estimates and subjective ratings. Total sleep time decreased from 7:38 h ± 12 min during holidays to 6:40 h ± 12 min during a regular school week. This 13% decrease elicited a partial compensation, as indicated by a 3% increase in sleep efficiency and a 6% decrease in the duration of nocturnal awakenings. During examination weeks total sleep time decreased to 6:23 h ± 8 min, but it was now accompanied by a decrease in sleep efficiency and subjective sleep quality and an increase in wake bout duration. In conclusion, school examination stress affects the sleep of adolescents. The compensatory mechanism of more consolidated sleep, as elicited by the sleep restriction associated with mere school attendance, collapsed during 2 weeks of sustained examination stress.     

Are qualitative and quantitative sleep problems associated with delinquency when controlling for psychopathic features and parental supervision?

The aim of this study was to explore the relationship between sleep, including both qualitative and quantitative aspects, and delinquent behaviour while controlling for psychopathic features of adolescents and parental supervision at bedtime. We analysed data from a nationally representative sample of 4855 Finnish adolescents (mean age 15.3 years, 51% females). Sleep problems, hours of sleep and delinquency were evaluated via self‐report. Psychopathic features were measured with the Antisocial Process Screening Device – Self‐Report. In negative binomial regressions, gender and sleep‐related variables acted as predictors for both property and violent crime after controlling for psychopathic features and parental supervision at bedtime. The results suggest that both sleep problems (at least three times per week, at least for a year) and an insufficient amount of sleep (less than 7 h) are associated with property crime and violent behaviour, and the relationship is not explained by gender, degree of parental supervision at bedtime or co‐occurring psychopathic features. These results suggest that sleep difficulties and insufficient amount of sleep are associated with delinquent behaviour in adolescents. The significance of addressing sleep‐related problems, both qualitative and quantitative, among adolescents is thus highlighted. Implications for a prevention technique of delinquent behaviour are discussed.     

Sleep patterns and insomnia among adolescents: a population‐based study

The aim of the current study was to examine sleep patterns and rates of insomnia in a population‐based study of adolescents aged 16–19 years. Gender differences in sleep patterns and insomnia, as well as a comparison of insomnia rates according to DSM‐IV, DSM‐V and quantitative criteria for insomnia (Behav. Res. Ther., 41 , 2003, 427), were explored. We used a large population‐based study in Hordaland county in Norway, conducted in 2012. The sample included 10 220 adolescents aged 16–18 years (54% girls). Self‐reported sleep measurements included bedtime, rise time, time in bed, sleep duration, sleep efficiency, sleep onset latency, wake after sleep onset, rate and frequency and duration of difficulties initiating and maintaining sleep and rate and frequency of tiredness and sleepiness. The adolescents reported short sleep duration on weekdays (mean 6:25 hours), resulting in a sleep deficiency of about 2 h. A majority of the adolescents (65%) reported sleep onset latency exceeding 30 min. Girls reported longer sleep onset latency and a higher rate of insomnia than boys, while boys reported later bedtimes and a larger weekday–weekend discrepancy on several sleep parameters. Insomnia prevalence rates ranged from a total prevalence of 23.8 (DSM‐IV criteria), 18.5 (DSM‐V criteria) and 13.6% (quantitative criteria for insomnia). We conclude that short sleep duration, long sleep onset latency and insomnia were prevalent in adolescents. This warrants attention as a public health concern in this age group.     

Preventing sleep deficit in adolescents: Long‐term effects of a quasi‐experimental school‐based intervention study

Adolescents are at risk of sleep deficit, which has serious consequences for their daytime functioning. However, school‐based interventions to improve sleep have shown limited success. This might be due to the content of the programmes (e.g., not targeting central factors such as daytime stress and technology use) or because changes have not been captured due to a lack of long‐term follow‐ups. Hence, the aim of this study was to evaluate the long‐term effects of a school‐based sleep education curriculum including time‐management training. The study used a quasi‐experimental design. Participants were 3,622 adolescents (mean age 13.7, 48% girls); 286 were in the intervention group and 3,336 were followed as a natural control group. Data were collected before the intervention and at a 1‐year follow‐up. We divided participants into three groups according to baseline sleep duration (calculated from self‐reported bed‐ and wake times, minus sleep onset latency): insufficient (<7 hr), borderline (7–8 hr) and adequate (>8 hr). Adolescents in the intervention group were ~2 times less likely to report insufficient sleep at follow‐up as compared to controls. Sleep knowledge improved significantly in the intervention group but there were no changes in emotional sleep hygiene (e.g., bedtime worry) and perceived stress. Surprisingly, technology use increased and behavioural sleep hygiene worsened in the intervention group. Although the mechanisms of change need further investigation, the results of this study point to potential long‐term benefits of school‐based sleep programmes.     

Effects of the COVID-19 pandemic on sleep quality in children and adolescents: A systematic review and meta-analysis

We synthesise the literature on the potential influence of the COVID-19 pandemic on sleep quality in children and adolescents. The search identified studies that examined the relationship between sleep quality and disorders during the COVID-19 pandemic. It began in May 2021 and has had two updates with the last in January 2022. The databases used were LILACS, PubMed, and EMBASE. Random effects models were performed to explore heterogeneity between studies. Data were presented as continuous variables (mean value and standard deviation) to perform a meta-analysis. Twenty-nine studies from 16 countries were identified: Nine had children and eight had adolescents. The overall quality of the studies ranged from high (27.6%) to medium (65.5%) and low (6.9%). Eight studies were eligible for meta-analysis. There was an increase in sleep duration during the pandemic when compared with the previous period 0.33 (95%CI −0.07; 0.60) (p < 0.001) and late bedtime 0.78 (95%CI −0.33; 1.22) (p < 0.001). A trend toward reduced sleep efficiency was also detected 0.54 (95%CI −0.75; −0.33) p = 0.20. Parents’ reports of increased use of screen media/electronic devices were associated with worse sleep quality. The results suggest an influence of the pandemic on sleep characteristics such as increased sleep duration, late bedtimes, and poor sleep quality. These alterations were related to changes in family routines during this period.     

Objectively measured night‐to‐night sleep variations are associated with body composition in very elderly women

This cross‐sectional study examined the association between objectively measured sleep patterns and body composition in very elderly community‐dwelling women. Participants included 191 community‐dwelling adults aged ≥ 80 years (mean age: 83.4 ± 2.6 years; age range: 80–92 years). Sleep and physical activity were monitored via accelerometer (ActiGraph GT3X+) during at least five consecutive 24‐h periods. Night‐to‐night sleep pattern variability across all nights of recording was assessed using standard deviations (SDs). Body composition was assessed using dual‐energy X‐ray absorptiometry. Simple and multivariable linear regression analyses were performed. The mean number of nights with usable actigraphy data was 7.3 ± 1.3. On average, participants went to bed at 22:57 hours (SD: 1.11 h) and rose from bed at 6:27 hours (SD: 1.01 h). Night‐to‐night bedtime, sleep duration and sleep timing mid‐point variations correlated slightly with the percentage body fat and percentage lean mass (P < 0.05). Multiple linear regression analysis revealed significant associations of night‐to‐night bedtime variations and inconsistent sleep–wake patterns with all body composition indices after adjusting for potential confounding factors, including mean nightly sleep duration, self‐reported nap duration and daily physical activity. After further adjusting for night‐to‐night wake time, sleep timing mid‐point and sleep duration variations, greater bedtime variability remained associated significantly with all body composition indices except lean/fat mass ratio. Inconsistent sleep–wake patterns were associated independently with an increased fat mass and decreased lean mass among very elderly women. These findings suggest that in most elderly individuals, sleep patterns might be an important modifiable factor associated with obesity and sarcopenia development.     

Prevalence and correlates of self-reported sleep problems among Chinese adolescents

STUDY OBJECTIVES: This study examined the prevalence and correlates of sleep problems in Chinese adolescents. DESIGN AND SETTING: An epidemiological questionnaire survey was carried out in five high schools in Shandong Province of Mainland China. PARTICIPANTS: A total of 1365 adolescents between the ages of 12 and 18 years comprising 823 boys and 542 girls. MEASUREMENTS AND INTERVENTIONS: The participants completed a self-administered questionnaire regarding sleep duration, sleep problems, stressful life events, lifestyles, and personal and family characteristics. RESULTS: Mean sleep duration at night was 7.64 hours (SD = 0.86) and decreased with increasing age. Of the sample, 16.9% (95% CI = 13.2-20.5%) reported insomnia symptoms including difficulty initiating sleep (10.8%), difficulty maintaining sleep (6.3%), and early morning awakening (2.1%). Nightmares were reported more frequently by girls (chi2=20.09, p<0.001). Only 2.3% of the sample had ever taken hypnotic medication during the past month. Almost 22% of the subjects went to bed later than 12:00 PM at least once a week. Multiple logistic regression analysis showed that greater age, being at senior high school, doing no habitual physical exercise, poor physical health, self-selection of diet, longer distance from home to school, and life stress experienced during the past 12 months were significantly associated with an increased risk of insomnia. CONCLUSIONS: Self-reported sleep problems in Chinese adolescents are common and associated with multiple factors. These findings suggest the need for comprehensive programs to prevent sleep problems in adolescents.     

Sleep duration estimates of Canadian children and adolescents

The objective of this study was to provide contemporary sleep duration estimates of Canadian school‐aged children and adolescents and to determine the proportion adhering to the sleep duration recommendations. This study included 24 896 participants aged 10–17 years from the 2013/2014 Canadian Health Behaviour in School‐aged Children study (HBSC), a nationally representative cross‐sectional study. Bedtime and wake‐up times were reported by participants and their sleep duration was calculated. Participants were then classified as having a sleep duration that met the recommended range (9–11 h per night for 10–13‐year‐olds or 8–10 h per night for 14–17‐year‐olds), a sleep duration that was shorter than the recommended range or a sleep duration that was longer than the recommended range. An estimated 68% of children aged 10–13 years and 72% of adolescents aged 14–17 years sleep for the recommended amount per night when averaged across all days of the week. Short sleepers represent 31% of school‐aged children and 26% of adolescents. Long sleepers are rare (<2% overall). Children and adolescents sleep ~1 h more at weekends compared to weekdays. Approximately 5% of the participants typically went to bed after midnight on weekdays and 31% did so at weekends; these proportions reached 11 and 45%, respectively, within 16–17‐year‐olds. In general, differences in sleep times between boys and girls are small and not clinically significant. In conclusion, almost one‐third of Canadian children and adolescents sleep less than the recommended amount. Public health efforts should continue to monitor the sleep of Canadian children and adolescents and identify subgroups of the population more likely to be affected by insufficient sleep.     

Prospective examination of adolescent sleep patterns and behaviors before and during COVID-19

Study ObjectivesTo prospectively examine changes in adolescent sleep before and during the COVID-19 pandemic in adolescents with and without ADHD.MethodsParticipants were 122 adolescents (ages 15–17; 61% male; 48% with ADHD). Parents reported on adolescents’ sleep duration and difficulties initiating and maintaining sleep (DIMS); adolescents reported on sleep patterns, sleep duration, delayed sleep/wake behaviors, and daytime sleepiness before (September 2019 to February 2020) and during (May–June 2020) COVID-19. Adolescents also reported on their health behaviors, COVID-19-related negative affect, and difficulties concentrating due to COVID-19.ResultsParents reported adolescents had more DIMS during COVID-19 than before COVID-19, with clinically elevated rates increasing from 24% to 36%. Both bedtimes and waketimes shifted later during COVID-19, and adolescents reported more delayed sleep/wake behaviors. Adolescents also reported less daytime sleepiness and longer school night sleep duration during COVID-19. In considering differences between adolescents with and without ADHD, adolescents with ADHD did not experience an increase in school night sleep duration and were less likely to obtain recommended sleep duration during COVID-19. In the full sample, controlling for ADHD status, COVID-19-related sadness/loneliness was associated with increases in DIMS, and spending less time outside and more COVID-19-related worries/fears were associated with increases in delayed sleep/wake behaviors during COVID-19.ConclusionsCOVID-19 had negative and positive impacts on adolescent sleep. Adolescents with ADHD did not experience the benefit of increased school night sleep duration during COVID-19 like adolescents without ADHD. Negative affect and health behaviors may be useful intervention targets for reducing negative impacts of COVID-19 for adolescent sleep.     

Sleep inertia,sleep homeostatic and circadian influences on higher‐order cognitive functions

Sleep inertia, sleep homeostatic and circadian processes modulate cognition, including reaction time, memory, mood and alertness. How these processes influence higher‐order cognitive functions is not well known. Six participants completed a 73‐day‐long study that included two 14‐day‐long 28‐h forced desynchrony protocols to examine separate and interacting influences of sleep inertia, sleep homeostasis and circadian phase on higher‐order cognitive functions of inhibitory control and selective visual attention. Cognitive performance for most measures was impaired immediately after scheduled awakening and improved during the first ~2–4 h of wakefulness (decreasing sleep inertia); worsened thereafter until scheduled bedtime (increasing sleep homeostasis); and was worst at ~60° and best at ~240° (circadian modulation, with worst and best phases corresponding to ~09:00 and ~21:00 hours, respectively, in individuals with a habitual wake time of 07:00 hours). The relative influences of sleep inertia, sleep homeostasis and circadian phase depended on the specific higher‐order cognitive function task examined. Inhibitory control appeared to be modulated most strongly by circadian phase, whereas selective visual attention for a spatial‐configuration search task was modulated most strongly by sleep inertia. These findings demonstrate that some higher‐order cognitive processes are differentially sensitive to different sleep–wake regulatory processes. Differential modulation of cognitive functions by different sleep–wake regulatory processes has important implications for understanding mechanisms contributing to performance impairments during adverse circadian phases, sleep deprivation and/or upon awakening from sleep.     

Sleep in healthy seniors: a diary study of the relation between bedtime and the amount of sleep obtained

The aim of this study was to determine whether naturally occurring inter-individual and intra-individual differences in bedtime selection in the elderly might be lawfully related to the amount of sleep that is obtained. A total of 128 seniors (63f, 65m) aged 70-92 years each provided a week of sleep diary data yielding a total of 896 subject-nights for analysis. From each subject-night the diary was used to derive measures of time in bed (TIB) and total sleep time (TST). These measures were used as dependent variables in mixed-effect linear models (nights nested within subjects) with the independent variable being bedtime for that subject-night, arbitrarily expressed as minutes since 19:00 hours. Although there were strong inter-individual and intra-individual differences, for both genders, bedtime had a statistically significant effect (P < 0.001) on both TIB and TST. We observed that later bedtimes were associated with less time in bed and less time asleep. On average between 7 and 8 min of less TIB and TST were associated with each 10-min delay in bedtime from 19:00 hours. These results are interpreted in terms of increases in sleep being derived from living in a better harmony with an earlier peaking circadian pacemaker characteristic of older age, although other possible mechanisms are also considered (e.g. age-dependent alterations in phase angle and homeostatic sleep need).