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

Late Bedtime from the Perspective of Adolescents: A Qualitative Study

Purpose

Later sleep timing is a key determinant of reduced sleep duration and quality in adolescents and is associated with negative mental and physical outcomes. However, little is known about adolescents' views on late bedtime. The study's purpose is to explore adolescents' perspectives on why they go to sleep late during school nights and what would help them to go to bed earlier.

Patients and Methods

We conducted online semi-structured interviews with 24 adolescents aged 14-17 years as a part of the international HBSC (Health Behaviour in School-aged Children) study. The data were collected via individual and group interviews and analyzed using a combination of consensual qualitative research methodology and thematic analysis.

Results

School demands and leisure time activities, particularly online socialization with peers, have been identified as one of the main themes related to why adolescents go to sleep late. Adolescents reported difficulties managing these competing activities during the day after school, often postponing them until late at night and prioritizing them to sleep. Adolescents also mentioned bedtime distress as a barrier to falling asleep. However, some adolescents did not perceive late bedtime as a problem, but rather as a habit and personal choice. They reported that better time management, less homework, engagement in physical activity, parent-set bedtime, and less time spent online in the evening would help them to go to bed earlier.

Conclusion

Our findings suggest that interventions to improve sleep timing in adolescents should focus on reducing school pressure, building supportive social networks; strengthening adolescents' self-regulation skills; and enhancing parental involvement in establishing sleep and daily routines for their adolescents.

The relationship between chronotype and mental toughness in adolescents: Is resilience a mediator?

OBJECTIVE

This study was designed to examine the mediator role of resilience in the relationship between chronotype and mental toughness in adolescents.

METHODS

The descriptive correlational study was completed with 342 high school students from one school in Türkiye (mean age 17.25±1.11 years). Data were collected with the Morningness-Eveningness Scale for Children, Child and Youth Resilience Measure, and Mental Toughness Scale for Adolescents. Hierarchical regression analyses with PROCESS Model 4 were used to evaluate the mediator effect.

RESULTS

It was observed that the morning chronotype tendency increased resilience (p < 0.001) mental toughness (p < 0.001). Higher resilience led to increased mental toughness. When the mediation effect was examined, resilience was a full mediator in the relationship between chronotype characteristics and mental toughness (β=0.396; p = 0.000).

CONCLUSIONS

According to these results, a morning chronotype tendency in adolescents increases their resilience and, therefore, mental toughness. These results suggest that effective methods for enhancing mental toughness in adolescents should be multifaceted. Additionally, it highlights the importance of identifying and regulating chronotype tendencies among adolescents, while also emphasizing the need to increase resilience in this demographic.

Associations between chronotype and physical activity and well-being in adults

Circadian rhythms influence a preference for people's time of activity and sleep time during the day and the hours of best performance. The aim of the study was to assess the associations between chronotype, physical activity, and well-being in adults aged 20-50. The chronotype, physical activity and well-being scores were determined based on the Composite Scale of Morningness (CSM) questionnaire, the International Physical Activity Questionnaire (IPAQ) and the Well-Being Index (WHO-5) questionnaire, respectively. Study data consisted of the answers of 213 respondents (including 64 men) who took part in an online survey. The Spearman rank correlation coefficient and the matrix scatter plots were used to check the correlations between the CSM score and quality of life parameters' values. General linear models (GLMs) were performed to find differences in quality-of-life parameters between different combinations of sex and chronotype. Morning types showed the highest value of well-being score (mean = 13.48) while evening types the lowest one (mean = 8.35). Evening types spent the most time sitting compared to other chronotypes. Results of this study revealed the significant effect of chronotype on well-being and physical activity among adults. These findings suggest that chronotype is an important factor that psychologists and personal trainers should take into account.

Lifestyle Factors Associated With Frequent Recurrent Headaches in Children and Adolescents: A Canadian Population-Based Study

BACKGROUND AND OBJECTIVES

Lifestyle behaviors have been postulated to affect headache frequency in youth and are often the primary target of self-management recommendations. Our study aimed to assess the association between various lifestyle factors and frequent recurrent headaches in children and youth.

METHODS

Children and adolescents aged 5-17 years were enrolled in a large cross-sectional Canadian population-based health survey, completed on January 31, 2019. Headache frequency was dichotomized into "approximately once/week or less" or ">once/week" (defined as frequent recurrent headaches). The association between frequent headaches and meal schedules, screen exposure, physical activity, chronotype, and frequent substance use/exposure (alcohol, cigarettes, electronic cigarettes, and cannabis) was assessed using both unadjusted logistic regression models and models adjusted for age/sex. Fully adjusted models examined the odds of frequent headaches according to all exposures. Survey design effects were accounted for using bootstrap replicate weighting.

RESULTS

There were an estimated nweighted = 4,978,370 eligible participants in the population. The mean age was 10.9 years (95% CI 10.9-11.0); 48.8% were female; 6.1% had frequent headaches. Frequent headaches were associated with older age (odds ratio [OR] = 1.31, 95% CI 1.28-1.34, p < 0.001) and female sex (OR = 2.39, 95% CI 2.08-2.75, p < 0.001). In models adjusted for age/sex, the odds of frequent headaches decreased with meal regularity (adjusted OR [aOR] = 0.90, 95% CI 0.89-0.92, p < 0.001) and increased with later chronotype (aOR = 1.10, 95% CI 1.05-1.15, p < 0.001) and excess screen exposure (≥21 hours vs none in past week: aOR = 2.97, 95% CI 1.53-5.77, p = 0.001); there was no significant association with reported physical activity (aOR = 0.95, 95% CI 0.67-1.34, p = 0.77). In 12- to 17-year-olds, frequent headaches were associated with frequent alcohol use (≥1/wk vs never: aOR = 3.50, 95% CI 2.18-5.62, p < 0.001), binge drinking (≥5 times in past month vs never: aOR = 5.52, 95% CI 2.95-10.32, p < 0.001), smoking cigarettes (daily vs never: aOR = 3.81, 95% CI 1.91-7.62, p < 0.001), using e-cigarettes (daily vs never: aOR = 3.10, 95% CI 2.29-4.20, p < 0.001), and cannabis use (daily vs never: aOR = 3.59, 95% CI 2.0-6.45, p < 0.001). In the entire sample, daily exposure to smoking inside the house was associated with frequent headaches (aOR = 2.00, 95% CI 1.23-3.27, p = 0.005).

DISCUSSION

Several lifestyle behaviors were associated with frequent headaches in children and youth, such as meal irregularity, late chronotype, prolonged screen exposure, and frequent substance use/exposure, suggesting that these are potential modifiable risk factors to target in this population.

The role of social support in the relation between chronotype and mental health in a cohort of women from the American Heart Association Go Red for Women Strategically Focused Research Network

Women are disproportionally affected by psychological distress and lack of social support and are more vulnerable to the negative impact of chronotype on mental health. This study evaluates cross-sectional associations between chronotype and mental health, while assessing the mediating role of social support among women from diverse racial/ethnic backgrounds. Women from the American Heart Association Go Red for Women Research Network were included (N = 506, mean age = 37 ± 15.7, 61% racial/ethnic minority). Chronotype, depression, perceived stress, health-related quality of life, and social support were assessed at baseline using validated self-reported questionnaires. Linear regression and causal mediation analyses were performed. Depression and negative emotionality were higher among women with evening vs. morning/intermediate chronotypes (all p < 0.05). Multivariable analyses adjusted for sociodemographic and clinical confounders showed associations between evening chronotype and higher depression (p = 0.004) and negative emotionality (p = 0.010). However, these associations were no longer significant after adjusting for social support (depression: p = 0.12; negative emotionality: p = 0.18). Social support significantly mediated 44.6% and 45.8% of the total effect of chronotype on depression and negative emotionality, respectively. Social support represents a potential mechanism underlying the associations between eveningness and poor mental health. Chronotype and social support should be considered in interventions for the promotion of mental health in women.

Associations of social jetlag with physical activity and sedentary behaviour in children and adolescents: A systematic review and meta-analysis

Sleep and daytime movement behaviours occur co-dependently with each other within a finite 24 h day. Sleep parameters other than sleep duration, such as social jetlag and chronotype, have been linked to health problems and unhealthy behaviours among children and adolescents. Given the increasing number of studies examining sleep timing/chronotype and weight-related behaviours, including physical activity and sedentary behaviour, in the past decade, this systematic review and meta-analysis collated and evaluated the evidence on the relationships of social jetlag and chronotype with physical activity and sedentary behaviour among children and adolescents aged 3-17 years. Seven databases were searched on 16 March 2022, and 52 studies were identified as eligible for inclusion, 47 of which were suitable for the meta-analysis. A positive association was found between social jetlag and screen media use (r = 0.14, 95% CI: 0.04-0.24; I2  = 96%; p = 0.008). The morning chronotype was associated with a higher level of physical activity and a lower level of sedentary behaviour than the evening chronotype. No relationship was found between social jetlag and physical activity. The magnitude of heterogeneity among the included studies was high. Further experimental studies are urgently required to understand how circadian preference or misalignment affects activity behaviours. Interventions to promote an active lifestyle in young populations should consider their circadian preference, especially among individuals with the evening chronotype.

Cardiorespiratory fitness and circadian rhythms in adolescents: a pilot study

Although cardiorespiratory fitness (CRF), an important marker of youth health, is associated with earlier sleep/wake schedule, its relationship with circadian rhythms is unclear. This study examined the associations between CRF and rhythm variables in adolescents. Eighteen healthy adolescents (10 females and 8 males; Mage = 14.6 ± 2.3 yr) completed two study visits on weekdays bracketing an ambulatory assessment during summer vacation. Visit 1 included in-laboratory CRF assessment (peak V̇o2) using a ramp-type progressive cycle ergometry protocol and gas exchange measurement, which was followed by 7-14 days of actigraphy to assess sleep/wake patterns and 24-h activity rhythms. During Visit 2, chronotype, social jetlag (i.e., the difference in midsleep time between weekdays and weekends), and phase preference were assessed using a questionnaire, and hourly saliva samples were collected to determine the dim light melatonin onset (DLMO) phase. All analyses were adjusted for sex, pubertal status, and physical activity. Greater peak V̇o2 was associated with earlier sleep/wake times and circadian phase measures, including acrophase, UP time, DOWN time, last activity peak (LAP) time, and chronotype (all P < 0.05). Peak V̇o2 was negatively associated with social jetlag (P = 0.02). In addition, the mixed-model analysis revealed a significant interaction effect between peak V̇o2 and actigraphy-estimated hour-by-hour activity patterns (P < 0.001), with the strongest effects observed at around the time of waking (0600-1000). In healthy adolescents, better CRF was associated with an earlier circadian phase and increased activity levels notably during the morning. Future studies are needed to investigate the longitudinal effects of the interactions between CRF and advanced rhythms on health outcomes.NEW & NOTEWORTHY In healthy adolescents, better cardiorespiratory fitness, as assessed by the gold standard measure [laboratory-based assessment of peak oxygen consumption (V̇o2)], was associated with earlier circadian timing of sleep/wake patterns, rest-activity rhythms and chronotype, and less social jetlag. These findings highlight the close interrelationships between fitness and rhythms and raise the possibility that maintaining higher cardiorespiratory fitness levels alongside earlier sleep/wake schedule and activity rhythms may be important behavioral intervention targets to promote health in adolescents.

A longitudinal investigation of sleep hygiene as a mediator linking parental warmth with adolescent sleep

STUDY OBJECTIVES

Parental warmth in adolescence protects sleep in early adulthood, yet the nature, directions, and mechanisms of this association across adolescence are unknown. This study examined parental warmth, adolescent sleep hygiene and sleep outcomes (morning/eveningness, school night sleep duration, and daytime sleepiness) across five annual waves, spanning four years, using a cross-lagged panel design.

METHODS

Adolescents and one primary caregiver (96% mothers) completed questionnaires assessing parental warmth (child- and parent-report) and adolescent sleep hygiene and sleep (child-report), across five annual waves: Wave 1 (N = 531, Mage = 11.18, SD = 0.56, 51% male), Wave 2 (N = 504, Mage = 12.19, SD = 0.53, 52% male), Wave 3 (N = 478, Mage = 13.19, SD = 0.53, 52% male), Wave 4 (N = 440, Mage = 14.76, SD = 0.47, 51% male), and Wave 5 (N = 422, Mage = 15.75, SD = 0.49, 51% male).

RESULTS

Greater child-reported parental warmth was indirectly associated with better adolescent sleep (greater morningness, longer school night sleep duration, less sleepiness) through healthier sleep hygiene. The inverse was also often observed. Warmth had a direct relationship with sleep duration and sleepiness, independent of sleep hygiene. Parent-reported parental warmth did not predict, nor was predicted by child-reported adolescent sleep.

CONCLUSIONS

Parental warmth may protect against developmental changes in adolescent sleep, partially by improving sleep hygiene practices. Similarly, inadequate adolescent sleep may negatively impact parental warmth via deteriorating sleep hygiene. Sleep hygiene emerged as a key mechanism for protecting adolescent sleep and parent-child relationships.

The influence of a permanent double-shift school start time on adolescent sleep and chronotype across different age groups

The main objective of this study was to explore the differences in sleep habits and chronotype across different age groups in Mexican adolescents attending a permanent double-shift school system. This cross-sectional study consisted of 1,969 (1,084 girls) students from public elementary, secondary, and high schools, as well as undergraduate university students from Mexico. Age range was 10-22 [15.33 ± 3.28 (mean ± SD)] years, 988 morning shift and 981 afternoon shift students. Questions regarding usual self-reported bedtime and rise time were collected, and from that, estimates for time in bed, midpoint of sleep, social jetlag, and chronotype were evaluated. Afternoon shift students reported later rise times, bedtimes, midpoint of sleep, and longer time in bed on school days than morning shift students, as well as less social jetlag. Overall, afternoon shift students reported a later chronotype than morning shift students. Peak lateness of chronotype in afternoon shift students was at age 15, with girls peaking at age 14 and boys at age 15. Meanwhile, morning shift students reported peak lateness of chronotype around age 20. In this study, adolescents from different age ranges attending an extremely delayed school start time reported adequate sleep compared with adolescents attending a fixed morning school start time. In addition, the analysis presented in this study seems to suggest that the peak of late chronotype may be influenced by school start times.

The association between various dimensions of sleep parameters and mental health: A large cross-sectional study of 13554 Chinese students

OBJECTIVES

We aimed to investigate the association between multiple sleep variables and mental health among Chinese students aged 9-22.

METHOD

We stratified the included 13,554 students by educational levels. Sleep parameters contained sleep duration on school days and weekends, napping time, chronotype and social jetlag (SJL), which were calculated via questionnaires. Individual psychological well-being and distress were assessed by Warwick-Edinburgh mental Well-being scale and the Kessler Psychological Distress Scale 10 respectively. The multiple linear and binary logistic regression were applied to analyze the association of sleep with mental health.

RESULTS

Short sleep on school days showed significantly positive association with psychological problems. While among senior high school students, we found reverse result that sleeping less might negatively associated with more severe distress (7-8 h: aOR = 0.67, 95% CI: 0.46, 0.97). The association of sleep duration with mental health was attenuated a lot on weekends. The chronotype was significantly related with mental health in primary and junior high school: intermediate chronotype (vs late chronotype) was associated with greater wellbeing (β = 1.03, 95% CI: 0.09, 1.96; β = 1.89, 95% CI: 0.81, 2.97) and less distress (aOR = 0.78, 95% CI: 0.60, 1.00; aOR = 0.73, 95% CI: 0.58, 0.91). The relationship between SJL, napping duration and psychological health problems were also observed in some educational levels.

CONCLUSION

Sleep deprivation on school days, late chronotype and SJL were positively associated with worse mental health in our study, which differed among various educational stages.

The associations of chronotype and social jetlag with prosocial behavior problems among Chinese adolescents

Potential relevance between the circadian rhythm and behavioral health has got raising attention in recent years. This study aimed to examine chronotype, social jetlag and their associations with prosocial behavior problems among Chinese adolescents. A total of 4,666 middle school students aged 12-18 years were enrolled in study. Sleep characteristics were collected by the modified Chinese version of Adolescent Sleep Hygiene Scale (M-ASHS); MSFsc and mid-sleep point were calculated to determine chronotypes and social jetlag. Prosocial behavior problems were assessed by the Strength and Difficult Questionnaire (SDQ). Multivariate logistic regression was applied to analyze the relationships between chronotype and social jetlag with prosocial behavior problems. Evening chronotype was associated with higher risk of prosocial behavior problems, whether among male (OR = 1.82, 95%CI:1.27-2.61, P = .001) or female adolescents (OR = 1.83, 95%CI:1.15-2.91, P = .011). Female adolescents with social jetlag of 1-2 hours had 1.60 times the risk of prosocial behavior problems than their peers whose social jetlag was <1 h (P = .028); social jetlag ≥ 2 h was positively associated with prosocial behavior problems in both male and female adolescents (OR = 1.79 and 2.45, respectively, both P < .05). Further, the combination of intermediate chronotype and social jetlag ≥ 2 h was correlated with prosocial behavior problems only in female adolescents (OR = 3.24, 95%CI = 1.40-9.21, P = .004). Evening chronotype and higher social jetlag were risk factors for prosocial behavior problems in adolescents, especially for the female. For the promotion of prosocial behavior in adolescents, the importance of circadian rhythm should be addressed.

Highlights of the ERS Lung Science Conference and Sleep and Breathing Conference 2021 and the new ECMC members

This article provides a brief description of some of the most remarkable sessions of the @EuroRespSoc Lung Science Conference and the Sleep and Breathing Conference 2021 and presents the new incoming members of the ECMC (@EarlyCareerERS) https://bit.ly/2RSDP40.

Sleep-wake rhythm and its association with lifestyle, health-related quality of life and academic performance among Japanese nursing students: a cross-sectional study

Background

Young adults are likely to have activities and go to bed late at night due to their age-dependent delayed endogenous circadian clock. The purpose of the present study was to clarify sleep–wake rhythm and its association with lifestyle, health-related quality of life, and academic performance among nursing students.

Methods

Self-reported questionnaires were distributed to undergraduate nursing students at six universities in Japan. Sleep–wake rhythm was assessed using the morningness-eveningness questionnaire. A quantitative design using the generalized linear mixed effect model was utilized to identify the factors related to the evening type among female nursing students (n = 447).

Results

About 18% of the participants were identified as the evening type. Evening type was associated with living alone, part-time job, and club activity. Sleep duration on weekdays was shorter, meal time duration was the shortest, and the percentages of students who skipped meals and those who gained body weight were higher in the evening type than in the morning type and intermediate type. Mental health-related quality of life was lower in the intermediate type and evening type than in the morning type, while there was no difference in physical health-related quality of life among these groups. The percentages of the nursing students who have experienced absence, tardiness, falling asleep during class, and/or interference with academic achievement were higher in the evening type than in other groups.

Conclusions

The present study has important implications for nursing students’ biological characteristics and lifestyle, which are associated with their health-related quality of life and academic performance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12912-021-00748-3.

Genetic and environmental influences on sleep-wake behaviors in adolescence

Study Objectives

To investigate the influence of genetic and environmental factors on sleep-wake behaviors across adolescence.

Methods

Four hundred and ninety-five participants (aged 9-17; 55% females), including 93 monozygotic and 117 dizygotic twin pairs, and 75 unmatched twins, wore an accelerometry device and completed a sleep diary for 2 weeks.

Results

Individual differences in sleep onset, wake time, and sleep midpoint were influenced by both additive genetic (44%-50% of total variance) and shared environmental (31%-42%) factors, with a predominant genetic influence for sleep duration (62%) and restorative sleep (43%). When stratified into younger (aged 9-14) and older (aged 16-17) subsamples, genetic sources were more prominent in older adolescents. The moderate correlation between sleep duration and midpoint (rP = -.43, rG = .54) was attributable to a common genetic source. Sleep-wake behaviors on school and nonschool nights were correlated (rP = .44-.72) and influenced by the same genetic and unique environmental factors. Genetic sources specific to night-type were also identified, for all behaviors except restorative sleep.

Conclusions

There were strong genetic influences on sleep-wake phenotypes, particularly on sleep timing, in adolescence. Moreover, there may be common genetic influences underlying both sleep and circadian rhythms. The differences in sleep-wake behaviors on school and nonschool nights could be attributable to genetic factors involved in reactivity to environmental context.

Chronotype and risk of post-menopausal endometrial cancer in the California Teachers Study

Working at night causes circadian disruption and it has been classified as a probable carcinogen. An evening chronotype, or preference for late day activity, has been shown to increase risk for several adverse health effects, such as metabolic disorders and recently, breast cancer. To further explore this emerging area of interest, we examined the association between endometrial cancer (EC) risk, another common cancer in women, and chronotype. The women in this study were members of the California Teachers Study cohort, which was established in 1995. Chronotype was reported on a subsequent questionnaire (Q5), administered in 2012-2013. The women included in this analysis were under age 90 years, were post-menopausal at Q5, and had no hysterectomy. The cancer cases, identified through linkages to the California Cancer Registry, were diagnosed between 1996 and 2014. We used unconditional logistic regression models to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) of the associations between chronotype and EC diagnosis. There were 437 EC cases and 26,753 cancer-free controls included in this analysis. Controls were more likely to classify themselves as current morning chronotypes than were cases (39% and 34%, respectively). Compared to morning types, women who were definite evening types had a statistically significantly elevated OR of 1.44 (95% CI 1.09-1.91). This association was more pronounced among obese women as compared to non-obese women. For evening type compared to morning type, the OR among obese women was 2.01 (95% CI 1.23, 3.29) while the OR for non-obese women was 1.12 (95% CI 0.77, 1.63). To our knowledge, the association between EC risk and evening chronotype has not been previously reported, but is consistent with the small body of literature which suggests increased breast cancer risks among evening chronotypes. Because this study was based on a retrospective analysis in a cohort of mostly white female teachers in California, further analysis of chronotype as a potential EC risk factor should be considered in other cohorts and in prospective analyses in order to further explore this relationship.

Biological Rhythm and Chronotype: New Perspectives in Health

The circadian rhythm plays a fundamental role in regulating biological functions, including sleep–wake preference, body temperature, hormonal secretion, food intake, and cognitive and physical performance. Alterations in circadian rhythm can lead to chronic disease and impaired sleep. The circadian rhythmicity in human beings is represented by a complex phenotype. Indeed, over a 24-h period, a person’s preferred time to be more active or to sleep can be expressed in the concept of morningness–eveningness. Three chronotypes are distinguished: Morning, Neither, and Evening-types. Interindividual differences in chronotypes need to be considered to reduce the negative effects of circadian disruptions on health. In the present review, we examine the bi-directional influences of the rest–activity circadian rhythm and sleep–wake cycle in chronic pathologies and disorders. We analyze the concept and the main characteristics of the three chronotypes.

A bio-ecological framing of evidence on the determinants of adolescent mental health - A scoping review of the international Health Behaviour in School-Aged Children (HBSC) study 1983-2020

This paper extracts, organises and summarises findings on adolescent mental health from a major international population study of young people using a scoping review methodology and applying a bio-ecological framework. Population data has been collected from more than 1.5 million adolescents over 37 years by the Health Behaviour in School-Aged Children: WHO Cross-National (HBSC) Study. The paper reviews the contribution that this long standing study has made to our understanding of the individual, developmental, social, economic, cultural determinants of adolescent mental health by organising the findings of 104 empirical papers that met inclusion criteria, into individual, microsystem, mesosystem and macrosystem levels of the framework. Of these selected papers, 68 were based on national data and the other 36 were based on international data, from varying numbers of countries. Each paper was allocated to a system level in the bio-ecological framework according to the level of its primary focus. The majority (51 papers) investigate individual level determinants. A further 28 concentrate primarily on the microsystem level, 6 on the mesosystem level, and 29 on the macrosystem level. The paper identifies where there is evidence on the determinants of mental health, summarises what we have learned, and highlights research gaps. Implications for the future development of this population health study are discussed in terms of how it may continue to illuminate our understanding of adolescent mental health in a changing world and where new directions are required.

Modifiable parental factors in adolescent sleep: A systematic review and meta-analysis

Sleep problems are prevalent during adolescence, but parents may be able to support adolescents to sleep better. A systematic search of records from six databases from inception up to November 2019, identified 103 peer-reviewed publications that examined behaviourally and cognitively modifiable parental factors associated with sleep in adolescents aged 12-18 years. Although included studies were largely cross-sectional and heterogeneous, with heavy reliance on self-reported measures, associations with sound, convergent levels of evidence were found for: 1) parental rule-setting for bedtimes and parent sleep behaviours with longer sleep duration in adolescents; 2) healthy parent sleep and family functioning with better adolescent sleep quality; and 3) parental warmth with better adolescent daytime functioning. Effect sizes were in the small to moderate range. The identified parental factors are recommended targets for inclusion in parenting programs to support adolescent sleep, however, would require validation in intervention studies. Opportunities for research are outlined for the identified parental factors, sleep domains with limited evidence, and better understanding the mechanisms or possible moderators in the associations between parental factors and sleep outcomes.

More than just sleeping in: a late timing of sleep is associated with health problems and unhealthy behaviours in adolescents

OBJECTIVE

New research suggests that the timing of sleep, or chronotype, affects the mental well-being of adolescents, however evidence of its links to physical health is limited. We investigated the associations between chronotype and various health outcomes and behaviours in a national sample of Canadian adolescents.

METHODS

Data were from the 2014 Canadian Health Behaviour in School-Aged Children survey (29,470 students; ages 10-18). Chronotype was estimated using the midpoint of sleep on weekends, corrected for catch-up sleep. We tested the associations with physical health (headache, stomach ache, back ache, dizziness, overweight, self-rated health) and health behaviours (consumption of fruits, vegetables, sweets, soft drinks, and energy drinks, smoking, physical activity, screen time) using random-effects regressions adjusted for sleep duration and individual, family, and school characteristics.

RESULTS

The average chronotype was 4:11 a.m. for boys and 4:10 for girls. Each 1-h delay in chronotype was associated with more headaches, stomach aches, and back aches [proportional odds ratios (PropORs) 1.08, 1.08, 1.07, respectively (boys), 1.10, 1.10, 1.08, respectively (girls)], and dizziness and worse self-rated health in girls (PropORs 1.10 and 1.09, respectively), but not overweight. A 1-h delay in chronotype also related to daily soft drink consumption [ORs 1.17 (boys), 1.11 (girls)], smoking [ORs 1.23 (boys), 1.37 (girls)], screen time [additional 0.64 h (boys), 0.74 h (girls)], less vegetable consumption in boys (OR 0.96), and daily energy drink consumption in girls (OR 1.42).

CONCLUSION

A later chronotype related to worse physical health and unhealthy behaviours in Canadian adolescents. Studies are needed to clarify the underlying mechanisms.