Association between morningness‐eveningness,sleep duration,weekend catch‐up sleep and depression among Korean high‐school students

The present study aimed to examine the association between morningness‐eveningness preferences, sleep duration, weekend catch‐up sleep duration and depression among Korean high‐school students. A total of 8,655 high‐school students participated from 15 districts in South Korea and completed an online self‐report questionnaire. The following sleep characteristics were assessed: weekday and weekend sleep duration, weekend catch‐up sleep duration, morningness‐eveningness preference, perceived sufficiency of sleep, self‐reported snoring and sleep apnea, daytime sleepiness, and sleep environment. Age, gender, body mass index, number of private classes, proneness to internet addiction, and depressive mood were also evaluated. A logistic regression analysis was conducted to compute odds ratios for the association between depression and sleep characteristics, after controlling for relevant covariates. Eveningness preference was a significant predictor of depressive mood (adjusted OR, 1.71; 95% CI, 1.47–1.99). Weekend CUS durations that were ≥2 hr and enrollment in numerous private classes were associated with a lower risk for depression (0.68, 0.55–0.85; 0.76, 0.60–0.95; respectively). Female gender, underweight and obese body weight, short weekday sleep durations, excessive daytime sleepiness, perceived excessiveness and insufficiency of sleep, self‐reported snoring and sleep apnea, proneness to internet addiction and a non‐optimal sleep environment were associated with an increased risk for depression. Eveningness preference and insufficient weekday sleep duration were associated with an increased risk for depression. Weekend CUS duration ≥2 hr reduced the risk for depression. Diverse aspects, including sleeping habits and sleep‐related environmental factors, should be considered to reduce depressive symptoms in late adolescents.     

Sleep duration and mortality – Does weekend sleep matter?

Previous studies have found a U‐shaped relationship between mortality and (weekday) sleep duration. We here address the association of both weekday and weekend sleep duration with overall mortality. A cohort of 43,880 subjects was followed for 13 years through record‐linkages. Cox proportional hazards regression models with attained age as time‐scale were fitted to estimate multivariable‐adjusted hazard ratios and 95% confidence intervals for mortality; stratified analyses on age (<65 years, ≥65 years) were conducted. Among individuals <65 years old, short sleep (≤5 hr) during weekends at baseline was associated with a 52% higher mortality rate (hazard ratios 1.52; 95% confidence intervals 1.15–2.02) compared with the reference group (7 hr), while no association was observed for long (≥9 hr) weekend sleep. When, instead, different combinations of weekday and weekend sleep durations were analysed, we observed a detrimental association with consistently sleeping ≤5 hr (hazard ratios 1.65; 95% confidence intervals 1.22–2.23) or ≥8 hr (hazard ratios 1.25; 95% confidence intervals 1.05–1.50), compared with consistently sleeping 6–7 hr per day (reference). The mortality rate among participants with short sleep during weekdays, but long sleep during weekends, did not differ from the rate of the reference group. Among individuals ≥65 years old, no association between weekend sleep or weekday/weekend sleep durations and mortality was observed. In conclusion, short, but not long, weekend sleep was associated with an increased mortality in subjects < 65 years. In the same age group, short sleep (or long sleep) on both weekdays and weekend showed increased mortality. Possibly, long weekend sleep may compensate for short weekday sleep.     

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.     

Short sleep duration in middle childhood: risk factors and consequences

STUDY OBJECTIVES: To measure sleep duration in 7-year-old children; identify the determinants of sleep duration; and assess the association between short sleep duration and obesity, cognitive functioning, and behaviour. DESIGN: Longitudinal study with disproportionate sampling of the participants. SETTING: Community. PARTICIPANTS: 591 seven-year-old children, of whom 519 had complete sleep data. INTERVENTIONS: Not applicable. MEASUREMENTS: Sleep duration was assessed by actigraphy. Other measurements included height, weight, BMI, percentage body fat as assessed by bioimpedance assay, intelligence (WISC-III) and behaviour (Strengths & Difficulties questionnaire, parent and teachers Conners Rating Scales). RESULTS: Mean time in bed according to parental report was 10.9 hours (SD 0.8). Mean sleep duration by actigraphy was 10.1 (SD 0.8) hours. In multivariable analysis, sleep duration was longer on weekdays vs. weekend nights (31.5 min, P = 0.002), in winter (40.5 min), autumn (31.1 min), and spring (14.8 min) compared with summer (P <0.0001), and in those with younger siblings (11.7 min, P = 0.03). Sleep duration was shorter when bedtime was after 21:00 (-41.1 min, P <0.0001). In multivariable analysis, sleep duration <9 hours was associated with being overweight/ obese (BMI: OR = 3.32; 95% CI = 1.40, 7.87) with an increase of 3.34% body fat (P = 0.03), and this was not explained by physical activity or television watching. Short sleep duration was also associated with higher emotional lability scores (Conners Rating Scale Parent Form; P = 0.03). IQ (WISC-III) and attention deficit / hyperactivity disorder scores (both parent and teachers Conners Rating Scales) did not differ with sleep duration. CONCLUSIONS: Sleep duration in 7-year-old children varies considerably among individuals. The duration is affected by weekday, season, and having younger siblings. Importantly, short sleep duration was shown to be an independent risk factor for obesity/overweight.     

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.     

The Association between Self-reported Sleep Duration and Body Mass Index among Korean Adolescents

Previous research has shown that lack of sleep is related to Body Mass Index (BMI) in adolescence. This study was designed to investigate the association between sleep duration and BMI among Korean adolescents. We conducted a school-based cross-sectional study of 3,785 adolescents (males: 58.2%, females: 41.8%) in middle and high school between the ages of 11 and 18 years (mean age 15.26 ± 1.45). Using a self-reported questionnaire, we obtained information regarding weekday sleep duration, weekend sleep duration, height, weight, time spent at private tutoring institutes, socioeconomic status and scores on the Beck Depression Inventory (BDI). We investigated the association between self-reported sleep duration and BMI. After adjusting for confounding factors including age, gender, time spent at private tutoring institutes, academic performance, economic status and BDI scores, longer sleep duration on both weekdays and weekends was associated with decreased BMI (P = 0.002 and P < 0.001, respectively) for both genders. Increased weekend catch-up sleep duration was associated with decreased BMI in females (P = 0.038), but not in males (P = 0.343). The results of the present study indicated that longer sleep duration on weekdays and weekends in adolescents was associated with lower BMI. Longer weekend catch-up sleep may compensate effects of insufficient sleep on BMI for female 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.     

Long sleep duration and childhood overweight/obesity and body fat

To assess the association between short sleep duration and overweight/obesity and body fat (BF) and to identify correlates of short sleep duration in a sample of Portuguese children. A cross‐sectional study of children 7–9 years (n = 4511) was performed between October 2002 and June 2003. Weight, height, and skinfolds were measured, and parents filled out a questionnaire about family characteristics as well as sleep duration. The prevalence of overweight/obesity and BF (%) both decreased by long sleep duration. After adjusted for confounders, the odds ratio (OR) for overweight/obesity and sleep duration were as follows: reference >11 h/d; 10–11 h/d, OR: 1.3; confidence interval (CI):1.26, 1.33; 9–10 h/d, OR: 1.16; CI: 1.13, 1.19; and <9 h, OR: 3.22; CI: 3.11, 3.32. Children whose parents' had a low educational level slept less time during each night than children whose parents' had a higher educational level; children who spent more time watching television slept less time than those who watched less television, and those children engaged in physical activity slept more time each night than sedentary children. Our results showed an inverse relationship between long sleep duration and overweight/obesity prevalence as well as with body fat, and these findings are important because sleep duration is a potentially modifiable risk factor that could be important to consider in the prevention and treatment of childhood obesity. Am. J. Hum. Biol., 2009. © 2009 Wiley‐Liss, Inc.     

Sleep patterns and insomnia in young adults: A national survey of Norwegian university students

The aim of this study was to describe sleep patterns and rate of insomnia according to diagnostic criteria in college and university students, as well as to examine potential changes in sleep problems from 2010 to 2018. Data stemmed from a national student health survey from 2018 for higher education in Norway (the SHoT study), which invited all 162,512 fulltime students in Norway. A total of 50,054 students (69.1% women) aged 18–35 years were included, yielding a response rate of 30.8%. Sleep parameters, reported separately for weekdays and weekends, included calculations of bedtime, rise time, sleep duration, sleep‐onset latency, wake after sleep onset, sleep need and sleep deficit. Insomnia was defined according to the Diagnostic and Statistical Manual of Mental Disorders (5th edn) criteria. For the trend analysis, we used one item measuring difficulties initiating and/or maintaining sleep, over three time points (2010, 2014 and 2018). The results from 2018 showed large weekday–weekend differences across most sleep parameters. Both male and female students obtained a mean sleep duration in the lower end of the normal range on weekdays (7:24 hr), but met their own sleep need and sleep recommendations at weekends (8:25 hr). The overall prevalence of insomnia was 34.2% in women and 22.2% in men. There was a substantial increase in sleep problems from 2010 (22.6%) to 2018 (30.5%), which was especially pronounced in women. We conclude that sleep problems are both prevalent and increasing among students. This warrants attention as a public health problem in this population.     

Sleep and academic performance in later adolescence: results from a large population‐based study

The aim of the current study was to assess the association between sleep duration and sleep patterns and academic performance in 16–19 year‐old adolescents using registry‐based academic grades. A large population‐based study from Norway conducted in 2012, the youth@hordaland‐survey, surveyed 7798 adolescents aged 16–19 years (53.5% girls). The survey was linked with objective outcome data on school performance. Self‐reported sleep measures provided information on sleep duration, sleep efficiency, sleep deficit and bedtime differences between weekday and weekend. School performance [grade point average (GPA)] was obtained from official administrative registries. Most sleep parameters were associated with increased risk for poor school performance. After adjusting for sociodemographic information, short sleep duration and sleep deficit were the sleep measures with the highest odds of poor GPA (lowest quartile). Weekday bedtime was associated significantly with GPA, with adolescents going to bed between 22:00 and 23:00 hours having the best GPA. Also, delayed sleep schedule during weekends was associated with poor academic performance. The associations were somewhat reduced after additional adjustment for non‐attendance at school, but remained significant in the fully adjusted models. In conclusion, the demonstrated relationship between sleep problems and poor academic performance suggests that careful assessment of sleep is warranted when adolescents are underperforming at school. Future studies are needed on the association between impaired sleep in adolescence and later functioning in adulthood.     

Sleep habits and disorders in Finnish schoolchildren

SUMMARY  A variety of epidemiological sleep parameters was evaluated in 574 Finnish schoolchildren (age 7 to 17 years) and in their parents (454 mothers and 390 fathers). Three questionnaire forms were set, one for the pupil and two for his/her parents including information of sleep habits, disorders, and social background of the pupil and his/her family. The pupils were grouped by age (two preadolescent groups: 7.1–9.3 y and 9.4–13 y, adolescents 13.1–17.1 y) and sex. It was found that bedtime was more often after 22.00 hours among adolescents than preadolescents both at weekends and on weekdays. At weekends the wake-up time was later in adolescents than preadolescents but on weekdays it was opposite in boys. On weekdays girls went earlier to bed than boys and woke up earlier than boys. Total sleep durations both on weekdays and at weekends were longer in preadolescent than in adolescent groups, and longer during weekend nights than on weekday nights in all groups. Girls experienced more dreaming and night waking, but boys snored more. Daytime sleepiness patterns were more common in adolescents than in preadolescents. Children who experienced daytime sleepiness more often had fathers with daily sleep urges.
An association was found between age and sleep habits and some daytime sleepiness patterns; adolescents went to bed later and slept less, and had more problems with alertness during daytime than preadolescents. Some differences were also found between boys and girls. The daytime sleepiness of pupils correlated with the same symptom in fathers.     

Associations of Sleep Duration and Screen Time with Incidence of Overweight in European Children: The IDEFICS/I.Family Cohort

IntroductionOver the past decades, children have been increasingly using screen devices, while at the same time their sleep duration has decreased. Both behaviors have been associated with excess weight, and it is possible they act as mutually reinforcing behaviors for weight gain. The aim of the study was to explore independent, prospective associations of screen time and sleep duration with incident overweight in a sample of European children.MethodsData from 4,285 children of the IDEFICS/I.Family cohort who were followed up from 2009/2010 to 2013/2014 were analyzed. Hours per day of screen time and of sleep duration were reported by parents at baseline. Logistic regression analyses were carried out in separate and mutually adjusted models controlled for sex, age, European country region, parental level of education, and baseline BMI z-scores.ResultsAmong normal weight children at baseline (N = 3,734), separate models suggest that every hour increase in screen time and every hour decrease in sleep duration were associated with higher odds of the child becoming overweight or obese at follow-up (OR = 1.16, 95% CI: 1.02–1.32 and OR = 1.23, 95% CI: 1.05–1.43, respectively). In the mutually adjusted model, both associations were attenuated slightly (screen time OR = 1.13, 95% CI: 0.99–1.28; sleep duration OR = 1.20, 95% CI: 1.03–1.40), being consistently somewhat stronger for sleep duration.Discussion/ConclusionBoth screen time and sleep duration increased the incidence of overweight or obesity by 13–20%. Interventions that include an emphasis on adequate sleep and minimal screen time are needed to establish their causal role in the prevention of overweight and obesity among European children.     

Fibrinogen may mediate the association between long sleep duration and coronary heart disease

Long sleep duration has been associated with increased risk of cardiovascular disease (CVD) and all‐cause mortality. Inflammation and coagulation have been hypothesized as possible physiological pathways to explain this association, although specific biomarkers have not been studied. Using longitudinal data from 3942 postmenopausal women in the Women's Health Initiative observational study and clinical trials, we investigated whether fibrinogen, an acute‐phase inflammatory protein involved in blood clotting, mediates the associations between sleep duration and coronary heart disease (CHD) and mortality among women. Fibrinogen levels were associated positively with self‐reported long sleep duration (9+ h per night), CHD and all‐cause mortality, even after adjustment for a range of sociodemographic characteristics, cardiovascular risk factors and comorbidities.Compared with self‐reported 7–8 h per night sleep duration, self‐reported long sleep duration was associated with increased odds of CHD [odds ratio (OR) = 2.05, 95% confidence interval (CI): 1.02–4.11]. Adjustment for fibrinogen levels reduced the increased odds of CHD associated with long sleep by approximately 8 percentage points (OR = 1.97, 95% CI: 0.98–3.97). A similar reduction in the OR was observed with mortality. For both outcomes there is support for partial mediation of 6–7%, suggesting that fibrinogen may be a mechanism through which long sleep duration is associated with CHD and mortality.     

Association between sleep duration and high blood pressure in adolescents: a systematic review and meta-analysis

Context: Sleep has been assessed as a risk factor for health consequences. Among adults, excessively longer and shorter sleep durations are associated with high blood pressure (BP), but knowledge of the association between sleep duration and high BP among adolescents is limited.

Objectives: To estimate the associations between sleep duration and high BP in adolescents.

Methods: PubMed, Web of Science, and Cochrane databases were searched for eligible publications up until 20 November 2017. This study reviewed the reference lists from retrieved articles to search for relevant studies. Pooled odds ratios (ORs) were calculated using a random-effects meta-analysis. Sub-group and sensitivity analyses were conducted to identify heterogeneity. Publication bias was evaluated using Egger’s test.

Results: Seven studies involving 21,150 participants were included, with ages ranging from 10–18 years. For primary analysis, compared with the reference sleep duration, the pooled OR for high BP was 1.51 (95% confidence interval [CI]?=?1.04–2.19) for the short sleep duration overall. For long sleep duration, the pooled OR was 1.04 (95% CI?=?0.78–1.38). Further sub-group analysis showed that short sleep duration had a higher risk of incident high BP in males (OR?=?1.55, 95% CI?=?1.24–1.93) than in females (OR?=?1.23, 95% CI?=?0.47–3.22).

Conclusions: Among adolescents, and particularly male adolescents, short sleep duration may be a risk factor for high BP. More attention should be given to this lifestyle factor.     

Short persistent sleep duration is associated with poor receptive vocabulary performance in middle childhood

The aim of this study was to examine whether short sleep duration is associated with poor receptive vocabulary at age 10 years. In the Quebec Longitudinal Study of Child Development, parents reported their children's nocturnal sleep duration annually from ages 2.5 to 10 years, and children were assessed for receptive vocabulary using the Peabody Picture Vocabulary Test—Revised (PPVT‐R) at ages 4 and 10 years. Groups with distinct nocturnal sleep duration trajectories were identified and the relationships between sleep trajectories and poor PPVT‐R performance were characterized. In all, 1192 children with available sleep duration and PPVT‐R data participated in this epidemiological study. We identified four longitudinal nocturnal sleep trajectories: short persistent sleepers (n = 72, 6.0%), short increasing sleepers (n = 47, 3.9%), 10‐h sleepers (n = 628, 52.7%) and 11‐h sleepers (n = 445, 37.3%). In all, 14.8% of the children showed poor PPVT‐R performance at age 10 years. Nocturnal sleep trajectories and poor PPVT‐R performance at age 10 were associated significantly (P = 0.003). After adjusting for baseline receptive vocabulary performance at age 4 and other potential confounding variables, logistic regression analyses suggest that, compared to 11‐h sleepers, the odds ratio of presenting poor receptive vocabulary at age 10 was 2.67 [95% confidence interval (CI): 1.24–5.74, P = 0.012] for short persistent sleepers and 1.66 (95% CI: 1.06–2.59, P = 0.026) for 10‐h sleepers. These results corroborate previous findings in early childhood, and indicate that short sleep duration is associated with poor receptive vocabulary during middle childhood.     

Development of sleep patterns in early adolescence

This study examines the developmental changes of sleep patterns as a function of gender and puberty and assesses the prevalence of sleep habits and sleep disturbances in early adolescence. It also investigates the relationship between sleep patterns, sleep habits and difficulty falling asleep and nocturnal awakenings. The present analyses are based on results available for 588 boys and 558 girls for whom mothers completed questions concerning demographics and sleep at annual intervals when their child was aged 10--13 years. The results indicated that nocturnal sleep times decreased, bedtimes were delayed and differences between weekend and school day sleep schedules progressively increased with age. Gender and puberty were both associated with the timing of sleep on weekends. Girls presented longer weekend time in bed (TIB) and later weekend wake time than boys. Similarly, subjects with higher pubertal status showed longer weekend TIB and later weekend wake time than subjects with lower pubertal status. Difficulty falling asleep was associated with later weekend wake time and with sleeping with a night light. In conclusion, the gender differences commonly reported in adolescents' sleep patterns are most likely explained by girls' higher pubertal status. This study emphasizes the link between puberty and a putative physiological need for more sleep, in presence of a general reduction of sleep times during adolescence. From age 10--13 years, the delay and lengthening of the sleep period on weekends in comparison to schooldays is associated with difficulty falling asleep.     

Weekend–weekday advances in sleep timing are associated with altered reward-related brain function in healthy adolescents

Sleep timing shifts later during adolescence, thus conflicting with early school start times. This can lead to irregular weekday–weekend schedules and circadian misalignment, which have been linked to depression and substance abuse, consistent with disruptions in the processing of rewards. We tested associations between weekend–weekday shifts in sleep timing and the neural response to monetary reward in healthy adolescents, using actigraphy and a functional magnetic resonance imaging paradigm. Region-of-interest analyses focused on the medial prefrontal cortex (mPFC) and striatum, both of which are implicated in reward function. Analyses adjusted for pubertal stage, sex, and total sleep time. Greater weekend–weekday advances in midsleep were associated with decreased mPFC and striatal reactivity to reward, which could reflect reduced regulatory response and reward sensitivity. We speculate that circadian misalignment associated with weekend shifts in sleep timing may contribute to reward-related problems such as depression and substance abuse.     

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.     

The impact of media use on sleep patterns and sleep disorders among school-aged children in China

STUDY OBJECTIVES: To determine the amount of television viewing and computer use in urban school-aged Chinese children, and to examine their associations with sleep/wake patterns, duration of sleep, and sleep disorders. DESIGN AND SETTING: Students representing 8 Chinese cities were studied during November and December 2005. PARTICIPANTS: A total of 19,299 elementary-school children, 49.7% boys and 50.3% girls, with a mean age of 9.00 years, participated in the survey. MEASUREMENTS: A parent-administered questionnaire and the Chinese version of the Children's Sleep Habits Questionnaire were completed to quantify media use and to characterize sleep patterns and sleep disturbances. RESULTS: A television or computer was present in the bedroom of 18.5% and 18.3% of Chinese school-aged children, respectively. Media presence in the bedroom and media use were positively correlated with later bedtimes, later awakening times, and a shorter duration of sleep during weekdays and weekends. They were also significantly associated with at least 2 types of sleep disturbances. Overall, the most affected sleep behaviors were bedtime and awakening time on the weekends, the duration of sleep during the weekdays, and sleep disorders of bedtime resistance and sleep anxiety. Television viewing > or = 2 hours/day on weekends, with a prevalence of 48.8%, was the predominant risk factor for all sleep disorders with the exception of the sleep duration disorder. Computer use, however, had no correlation with any sleep disorder. CONCLUSION: The presence of media in a child's bedroom and media use had a negative effect on children's sleep/wake patterns, duration of sleep, and sleep disorders.     

Teenage night owls or early birds? Chronotype and the mental health of adolescents

Evidence suggests that the timing of sleep (chronotype) impacts mental health in young people, but previous studies have not accounted for sleep duration or school start time in this association, or examined a broad range of mental outcomes. In this study, we investigated the association between chronotype and mental health in a representative sample of adolescents from the 2014 Canadian Health Behaviour in School‐Aged Children survey (29,635 students, 362 schools). We examined positive and negative aspects of mental health, using scores for emotional problems (range 0–33), emotional well‐being (0–22), behavioural problems (0–28) and prosocial behaviours (0–25). We estimated chronotype using the time of mid‐sleep on weekends and examined the associations using multilevel regressions, adjusted for sleep duration, school start time, individual, family and geographic characteristics. The average time of mid‐sleep (chronotype) was 04:11 hr. An hour delay in mid‐sleep time was associated with more emotional problems (0.34 [95% confidence interval 0.23, 0.45] point higher score), more behavioural problems (2.0% [95% confidence interval 1.4%, 2.6%] higher score), less emotional well‐being (0.19 [95% confidence interval 0.09, 0.20] point lower score), and fewer prosocial behaviours (0.18 [95% confidence interval 0.08, 0.29] point lower score). A later chronotype was associated with poorer mental health, independent of sleep duration and school start time, and across internalizing and externalizing mental health domains. Further research is needed to clarify the mechanisms underlying this association. The timing of sleep, and not just its duration, may be an additional consideration for youth mental health.