Circadian typology and implications for adolescent sleep health. Results from a large, cross-sectional, school-based study

Sleep duration and social jetlag in healthy adolescents. Association with anxiety, depression, and chronotype: a pilot study

PURPOSE

Misalignment between sleep opportunity and chronotype preference during adolescence may affect sleep and mental health. The aim of this study was to objectively evaluate sleep duration and social jetlag (SJL) to observe if there is a relationship with anxiety, depression, or chronotype.

METHODS

Community based cohort study (n = 65) was conducted in Northern Europe. Participants recorded their sleep during the regular school schedule for 3 school nights and 2 free nights with FDA-cleared/EU Medical Device Directive (CE-02862) compliant home sleep test. They also completed validated questionnaires to assess (Morningness Eveningness Questionnaire; MEQ), sleepiness (Epworth Sleepiness Scale; ESS), and insomnia (Insomnia Severity Index; ISI), anxiety (General Anxiety Disorder-7; GAD-7), and depression symptoms (Beck's Depression Inventory-II; BDI-II). Data were collected during the last week of February and the first 2 weeks of March, 2023.

RESULTS

Average sleep duration on school nights was 7 h, 15 min, with 18% of participants on average sleeping ≥ 8 h. Average sleep onset was significantly later on free nights (1 hour, 47 minutes; p < 0.0001) causing a high prevalence of moderate-severe SJL, in 71% of participants. Evening chronotypes (prevalence 15.4%) fell asleep later on free nights, causing them to have significantly more SJL (2 hours, 58 minutes) than morning chronotypes (1 hour, 32 minutes) and intermediary chronotypes (1 hour, 36 minutes). Evening chronotypes also had more severe insomnia (ISI + 4.4, p = 0.006; + 4.0, p = 0.001) and greater depressive symptoms (BDI-II + 21.6, p < 0.0001; + 17.1, p < 0.0001). A significant negative correlation was observed between MEQ scores and ESS (r =  - 0.287; p = 0.001), ISI (r =  - 0.343, p < 0.0001), GAD-7 (r =  - 0.185, p < 0.0001), BDI-II (r =  - 0.501, p = 0.0001), and suicidal thoughts (r =  - 0.294, p = 0.017).

CONCLUSION

Adolescents are sleep-deprived and have a high prevalence of SJL that is positively correlated with depressive symptoms and evening chronotype. That evening chronotypes have shorter sleep duration, more severe SJL, and significantly more sleepiness and insomnia, anxiety, and depressive symptoms may indicate possible benefits in identifying this group with the aim to assist them in improving their sleep habits with potentially positive effects on mental health.

Interactive Screen-Based Activities Predict Worse Actigraphic Sleep Health That Night Among Adolescents

PURPOSE

To determine the micro-longitudinal effects of duration and timing of screen-based activities on sleep within and between adolescents.

METHODS

Daily survey and actigraphy data from the age 15 wave of the Future of Families and Child Wellbeing Study were analyzed using multilevel modeling. Four hundred seventy five adolescents provided three or more days of valid daily survey and nighttime sleep data.

RESULTS

Within-person results showed that on days when adolescents played video games more than their daytime average ± SE (1.3 ± 1.2 hours), sleep onset (6 ± 2 minutes, p < .01) and midpoint (4 ± 2 minutes, p < .02) were delayed for each additional hour of gaming. Between-person results showed that for each hour adolescents used screens to communicate with friends across the day, sleep onset was later (11 ± 3 minutes, p < .01), sleep midpoint was later (8 ± 3 minutes, p < .01), and sleep duration was shorter (-5 ± 2 minutes, p < .03). Adolescents who used screens to communicate with friends or play video games in the hour before bed had later sleep onset (30 ± 14 minutes, p < .03) and midpoint (25 ± 13 minutes, p < .05).

DISCUSSION

Among adolescents, passive screen usage such as browsing the Internet or watching videos may not affect sleep timing or duration, but limiting interactive screen-based activities could protect adolescent sleep health and well-being.

Association of sleep timing and sleep variability with health-related outcomes in a sample of Brazilian adolescents

OBJECTIVES

This cross-sectional study aimed to examine the relationships of sleep timing and sleep variability with depressive symptoms, health-related quality of life (HRQoL), daytime sleepiness, and body mass index (BMI) in adolescents.

METHODS

Adolescents from three schools (n = 571, 56% female, 16.3 ± 1.0 years) had their sleep examined by actigraphy, their anthropometrics assessed, and answered a survey. Sleep timing was examined by combining groups of median-dichotomized onset and wakeup times (early onset and early wakeup; early onset and late wakeup; later onset and early wakeup; later onset and later wakeup); sleep variability was based on within-participant standard deviations of onset and wakeup; and sleep duration as the length of time between onset and wakeup. The sleep variables were separated for weekdays and weekend. Mixed linear models were fitted to compare each sleep variable with health-related outcomes.

RESULTS

Higher values of daytime sleepiness were observed in adolescents from the late-early and late-late timing group during the week. Greater sleep midpoint and wakeup variability on weekdays were related with higher daytime sleepiness. Adolescents in the late-late and early-late groups showed higher daytime sleepiness. Increased of all sleep variability variables was related with greater daytime sleepiness. Higher depressive symptoms scores were found among adolescents in the late-early subgroup and with the increase of sleep variability. Participants with greater sleep onset variability and sleep midpoint variability reported less HRQoL.

CONCLUSIONS

Not only sleep duration, but sleep timing and variability also relate to health outcomes, and should be addressed by policies and interventions among adolescents.

Morning compared to afternoon school-based exercise on cognitive function in adolescents

PURPOSE

Adolescents may be less ready to learn in the mornings due to a propensity for waking up later. High-intensity interval exercise (HIIE) has been shown to acutely improve cognitive functioning in teenagers. This within-measures study explored whether the benefit of HIIE differs when delivered in the morning or afternoon.

METHODS

37 teenagers (19 boys, 13.7 ± 0.4 years) each completed 3 trials in school; morning HIIE (MORN), afternoon HIIE (AFTER) and a no-exercise control trial (CON). The HIIE involved 10x10 second sprints, interspersed by 50 s of walking. Cognitive function was assessed using a battery of computerised tasks four times over the course of the day.

RESULTS

Z scores for reaction time, but not proportion of correct responses, were improved 45 min post exercise in the MORN trial (P < 0.01, d = 0.47), and this improvement persisted until the third (P = 0.04, d = 0.34), but not final (P = 0.93, d = 0.01), time point. Global reaction time was not improved 45 min post exercise in the AFTER trial (P = 0.17, d = 0.20). Global reaction time was quicker 45 min post morning exercise compared to the same time point in CON (P = 0.02, d = 0.56) and AFTER (P = 0.01, d = 0.72).

CONCLUSION

HIIE may be more effectual in improving cognitive functioning when delivered in the morning.

Association between COVID-19 lockdown and sleep behaviors in Korean adolescents

To find the effect of coronavirus disease 2019 (COVID-19)-related sleep behavior changes using school-based self-reported data from a nationally representative Korean adolescent population. We analyzed web-based self-reported data from the Korean Youth Risk Behavior Web-based Survey in 98,126 participants (51,651 in 2019 [before the COVID-19 pandemic]; 46,475 in 2020 [during COVID-19 pandemic] 12 through 18 years old were included in this study. Self-report questionnaires were used to assess socioeconomic status, health behaviors, psychological factors, and sleep patterns. During the COVID-19 pandemic, Korean adolescents had a later weekend bedtime (≥1:00 am: 68.2% vs 71.5%, P < .001) and late weekend wake time (≤7:00 am: 13.3% vs 10.7%, P < .001) compared to before COVID-19 pandemic. Average sleep duration (434.7 ± 102.6 vs 428.2 ± 100.4 minutes; P < .001) was significantly lower during the COVID-19 pandemic and weekend catch-up sleep >2 hours (42.1% vs 43.7%; P < .001), late chronotype (17.1% vs 22.9%, P < .001) were significantly higher during COVID-19 pandemic. After adjusting for multiple confounding variables, short sleep duration (≦5 hours, odds ratio [OR] 1.14; 95% confidence interval [CI] 1.10-1.19), 6 hours, OR 1.07; 95% CI 1.03-1.12), long weekend catch-up sleep (OR, 1.08; 95% CI, 1.06-1.11) and late chronotype (OR, 1.43; 95% CI, 1.38-1.47) were significantly associated with COVID-19 pandemic. The COVID-19 pandemic was associated with changes in sleep behavior among Korean adolescents, resulting in later bed and wake-up times, increased weekend catch-up sleep, and a shift of chronotype toward eveningness.

Later school start time is associated with longer school day sleep duration and less social jetlag among Norwegian high school students: Results from a large-scale, cross-sectional study

The present study explored the associations between school start time and sleep habits among older adolescents, and whether these associations depended on circadian preference. The sample comprised 4010 high school students aged 16-17 years who completed a web-based survey on habitual school start time, sleep, and health. The survey included the Munich ChronoType Questionnaire, and the short version of the Horne-Östberg Morningness-Eveningness Questionnaire. Students were categorised according to habitual school start time (before 08:00 hours, 08:00 hours, 08:15 hours, 08:30 hours or after 08:30 hours) and circadian preference (morning, intermediate or evening). Data were analysed using two-way analyses of variance (school start time × circadian preference) and linear regression analyses. Results showed an overall effect of school start time on school day sleep duration (main effect, p < 0.001), with the latest school starters having the longest, and the earliest school starters having the shortest sleep duration (7:03 hr versus 6:16 hr; Tukey HSD p < 0.001). Similarly, later school starters generally reported shorter social jetlag and later school day wake-up times than earlier starting students (both main effect p < 0.001). Circadian preference did not modify these associations (interaction effects p > 0.05). In the crude regression analysis, 15 min later school start was associated with 7.2 min more sleep (p < 0.001). School start time remained a significant predictor of school day sleep duration when adjusted for sex, parental educational level and circadian preference (p < 0.001). Results suggest that school start time is a significant predictor of school day sleep duration among adolescents.

Sleep Disturbances in Adolescents with Attention-Deficit/Hyperactivity Disorder

Introduction

Delayed sleep phase syndrome (DSPS) and insomnia disorders are prevalent in adolescents and are comorbid with attention-deficit/hyperactivity disorder (ADHD), but only limited information is available regarding the prevalence of DSPS and insomnia in adolescents with ADHD. Moreover, previous studies comparing objective sleep parameters averaged the findings across all participants of each group (ADHD, control) regardless of each individual's level of reported sleep disturbance. This might have resulted in inconsistency between information obtained by objective and subjective sleep measures in adolescents with ADHD. The objectives of the present study were 1) to compare the prevalence of risk for DSPS and insomnia in adolescents with ADHD and control adolescents in our samples; 2) to compare objectively measured sleep characteristics of adolescents with ADHD and controls while taking into consideration their levels of risk for DSPS or their level of insomnia; and 3) to compare the ADHD symptom levels of adolescents with moderate/high and low risk for DSPS or insomnia.

Methods

Seventy-three adolescents (37 ADHD, 36 controls) aged 12-15 years participated in a cross-sectional study. Actigraphy was used to characterize objective sleep parameters and parents' or adolescents' reports were used to characterize subjective sleep parameters.

Results

Of the participants in the ADHD and control groups, 33.33% and 27%, respectively, had moderate/high levels of risk for DSPS. Adolescents in the high-risk group for DSPS had an objectively measured delayed sleep schedule and more variable sleep duration, time in bed, and sleep efficiency compared to adolescents in the low-risk group for DSPS, regardless of their ADHD diagnosis. Adolescents with higher levels of insomnia spent more time in bed and had more variable sleep efficiency compared to adolescents with no insomnia, regardless of their diagnosis.

Conclusion

The prevalence of moderate/high risk for DSPS was similarly high in adolescents with ADHD and controls. Participants' subjective reports of sleep disturbances were consistent with their objective sleep parameters when the type and level of subjectively defined sleep disturbance were considered. ADHD symptom levels were not different in adolescents with moderate/high or low risk for DSPS or insomnia.

Association between Chronotype and Sleep Quality among Chinese College Students: The Role of Bedtime Procrastination and Sleep Hygiene Awareness

Chronotype and sleep quality have been shown to play significant roles in influencing people's physical and mental health. The current study focuses on examining the relationship between chronotype and sleep quality among Chinese college students and exploring the mediating role of bedtime procrastination and the moderating role of sleep hygiene awareness. A sample of 2822 college students (female = 71.4%) aged between 17 and 29 years (M = 19.77, SD = 1.41) were included and completed the measures of the Pittsburgh Sleep Quality Index (PSQI), Morningness-Eveningness Questionnaire (MEQ), Bedtime Procrastination Scale (BPS) and Sleep Hygiene Awareness Scale (SHAS). The results showed that evening-type students reported the lowest sleep quality and highest levels of bedtime procrastination. In contrast, the highest sleep quality and lowest levels of bedtime procrastination were shown by morning-type, exhibiting the neither-type students' intermediate chronotype. Bedtime procrastination partially mediated the relationship between chronotype and sleep quality. Furthermore, sleep hygiene awareness moderated the direct effect of chronotype on sleep quality and the effect of chronotype in the path from chronotype to bedtime procrastination. Specifically, higher levels of sleep hygiene awareness could buffer the adverse effect of chronotype on self-reported sleep quality but bolstered the negative effect of chronotype on bedtime procrastination. Our results suggest that individuals with an evening preference are inclined to postpone their bedtime and further experience poorer sleep quality at night. Sleep hygiene awareness may serve as a protective factor for poor nocturnal sleep. Overall, the findings highlight the importance of reducing bedtime procrastination and improving sleep hygiene awareness in the interventions designed to help college students to own a better sleep quality, especially for those with evening chronotypes.

Circadian preference in young adults: Associations with sleep and mental health outcomes from a national survey of Norwegian university students

Individual preferred timing of sleep and activity patterns, known as circadian preference, ranges from definitely morning types to definitely evening types. Being an evening type has been linked to adverse sleep and mental health outcomes. This study aimed to explore the associations between circadian preference and self-reported sleep, depression, anxiety, quality of life, loneliness, and self-harm/suicidal thoughts. Data stem from a national survey of students in higher education in Norway (the SHoT-study). All 169,572 students in Norway were invited to participate, and 59,554 students (66.5% women) accepted (response rate = 35.1%). Circadian preference was associated with sleep and mental health outcomes in a dose-response manner. For both genders, being an evening type (either definitely evening or more evening than morning) was associated with an increase in age-adjusted relative risk (RR-adjusted; range = 1.44 to 2.52 vs. 1.15 to 1.90, respectively) across all outcomes compared with definitely morning types. Overall, the present study provides further evidence that evening circadian preference is associated with adverse sleep and mental health outcomes in young adults. As such, future efforts to improve sleep and mental health in young adults should consider their circadian preferences.

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.

Changes in sleeping habits during the pubertal years; A descriptive study conducted in Jordan

Background:

There is limited information about changes in sleeping habits during the pubertal years of development among adolescents in Jordan.

Objective:

This study examined sleeping habits at the onset and end of puberty.

Methods:

This study utilized data from a nationwide survey in Jordan.

Participants: Sleeping habits were obtained from 3,661 adolescents aged 11(onset of puberty) and 15 years (end of puberty) and their mothers using a self-reported questionnaire. The number of hours slept and bedtimes and wake-up times on both school and non-school days were examined.

Results:

On school days, 60% of 11-year-old and 34% of 15-year-old adolescents slept between 8:00-10:00 pm. On school days, the 11-year-old adolescent group reported sleeping significantly longer than the 15-year-old adolescent group, and the proportions of adolescents who met the minimal recommended sleeping hours were 64% and 54%, respectively. Sleeping hours were long for both groups attending government schools; for the 15-year-old adolescent group, sleeping hours varied with family income and maternal education. In the case of both groups, on non-school days sleeping hours varied with gender, family income, and type of school.

Conclusion:

At the end of pubertal years, adolescent sleeping habits differ significantly from those of adolescents at the onset of puberty. On school days, insufficient sleep is much evident in the case of both 11 and 15-year-old adolescent groups, but more pronounced in the latter. Nursing initiatives to address poor sleeping habits among adolescents are warranted, given their efficacy in promoting healthy growth and development within this age group.

Sleep’s role in the development and resolution of adolescent depression

Two adolescent mental health fields — sleep and depression — have advanced largely in parallel until about four years ago. Although sleep problems have been thought to be a symptom of adolescent depression, emerging evidence suggests that sleep difficulties arise before depression does. In this Review, we describe how the combination of adolescent sleep biology and psychology uniquely predispose adolescents to develop depression. We describe multiple pathways and contributors, including a delayed circadian rhythm, restricted sleep duration and greater opportunity for repetitive negative thinking while waiting for sleep. We match each contributor with evidence-based sleep interventions, including bright light therapy, exogenous melatonin and cognitive-behaviour therapy techniques. Such treatments improve sleep and alleviate depression symptoms, highlighting the utility of sleep treatment for comorbid disorders experienced by adolescents.

Sleep problems are both a symptom and precursor of adolescent depression. In this Review, Gradisar et al. describe how the combination of adolescent sleep biology and psychology predisposes adolescents to develop depression, and describe interventions that improve sleep and depression symptoms in this population.

Adolescent circadian patterns link with psychiatric problems: A multimodal approach

Circadian rhythms orchestrate brain function and mental wellbeing. We compared circadian patterns derived from continuous measurements of body temperature, sleep actigraphy and self-reported circadian preference in relation to different psychiatric disorders. 342 adolescents (70% females) aged 17.4y underwent M.I.N.I. psychiatric interviews, wore Ibutton 1922L skin temperature loggers (n = 281; 3 days), completed one-week GeneActiv Original actigraphy measurements (n = 306) and responded to Morningness-Eveningness Questionnaire (MEQ; n = 330). We derived circadian period length and amplitude from the temperature loggers. Actigraphy measures included sleep duration, midpoint, efficiency, and irregularity as well as Delayed Sleep Phase (DSP) characteristics (bedtime after 1 a.m. 3 times/week). M.I.N.I. psychiatric interviews suggested that 36% of participants had one or more psychiatric problem, with 21% suffering from comorbidity. Severe depression was associated with longer circadian period (p = 0.002). Suicidality was associated with later midpoint (p = 0.007) and more irregular sleep (p = 0.007). Those with agoraphobia slept longer (p = 0.013). Manic episodes and psychotic disorders were associated with irregular sleep (p-values <0.02). DSP was related to suicidality (p = 0.026), panic disorder (p = 0.022), and greater comorbidity (p = 0.026). Preference for eveningness was similarly related to higher prevalence of Generalized Anxiety Disorder (p = 0.014), social anxiety (p = 0.03), agoraphobia (p = 0.026), panic disorder (p = 0.004), suicidality (p = 0.018), severe depression (p < 0.001), and comorbidity (p < 0.001). Deviations in circadian rhythms were widely associated with psychiatric problems, whereas sleep duration was not. Especially suicidality linked with several markers of circadian disruption: later sleep midpoint, irregular sleep, and DSP characteristics. Longer circadian period length was associated with severe depression.

The Relationship Between Circadian Typology and Dry Eye Symptoms in Chinese College Students

PURPOSE

To explore the relationship between symptomatic dry eye and circadian typology in college students.

METHODS

This study included 269 students from 3 Chinese universities. All participants completed the ocular surface disease index (OSDI) questionnaire, the morningness-eveningness questionnaire (MEQ), and the Pittsburgh sleep quality index (PSQI) questionnaire. Participants were grouped into 3 types by the reduced MEQ (rMEQ) score:E-Type, N-Type, and M-Type. All these parameters were then analyzed for the effect on the severity of dry eye.

RESULTS

The occurrence rates of poor sleep quality (PSQI>5) and symptomatic dry eye (OSDI > 13) in the college students were 53.2% and 40.2%, respectively. The distribution of the circadian typology differed significantly among the college students with different dry eye severities (χ ² = 59.44, P = 0. 000), and E-type was associated with the most severe dry eye symptoms. The OSDI and PSQI scores were both significantly different among college students with different chronotypes (F = 22.14, P = 0.000; F = 15.21, P = 0.000; respectively). For both scores, the E-type scored the highest, followed by N-type, and M-type was the lowest. The circadian typology was an independent factor for dry eye. The risk of E-Type was 6.99 times higher than that of M-Type (P = 0.000), and the risk of N-types was 3.23 times higher than that of M-Type (P = 0.000). Sleep quality was also an independent risk factor for dry eye (P = 0.000). Gender and awareness of dry eye were not risk factors for dry eye.

CONCLUSION

The severity of dry eye symptoms and sleep quality were associated with different circadian typologies. The more the circadian preference tended to be E-type, the worse the sleep quality and the more serious dry eye symptoms would appear.

The Association Between Dry Eye and Sleep Disorders: The Evidence and Possible Mechanisms

Dry eye is a disease that severely affects patients' quality of life, increasing the global burden on public health and finance. There is growing evidence that a poor lifestyle is a significant risk factor for dry eye. Along with the development of society, sleep, as a way of life, is also constantly changing. The main manifestations of sleep disorders are reduced sleep time, circadian rhythm disturbances, and sleep breathing disturbances. Sleep disorders and their secondary systemic diseases have attracted wide attention in recent years. This review mainly explored the correlation between sleep disorders and dry eye, and found that sleep-related problems and other factors potentially leading from sleep disorders could be critical factors for dry eye. These results suggest that ophthalmologists should pay attention to the sleep health problems in patients with dry eye, and we hope that this paper can provide help for future research in this field.

Too Jittery to Sleep? Temporal Associations of Actigraphic Sleep and Caffeine in Adolescents

Caffeine consumption has been linked to poor sleep health in adolescents, but it is unknown whether poor sleep predicts caffeine consumption, and/or whether caffeine consumption predicts poor sleep, particularly when sleep is measured objectively. Data were collected from a micro-longitudinal sub-study of the age 15 wave of the Fragile Families and Child Wellbeing Study (n = 589). Adolescents wore an actigraphy device and completed daily surveys for ~1 week. Daily surveys assessed subjective sleep quality and caffeinated beverage consumption (0 = no caffeine, 1 = any caffeine). Separate mixed models assessed whether actigraphy-measured sleep duration, timing, maintenance efficiency, and subjective quality predicted next-day caffeinated beverage consumption within and between adolescents. Variability (standard deviation) of sleep duration and timing, sleep regularity index, and social jetlag were tested as additional between-person predictors. Lagged models tested whether daily caffeinated beverage consumption predicted sleep that night (n = 458). Adolescents with more variable sleep duration and midpoint had higher average odds of consuming caffeinated beverages compared to others. After adolescents consumed ≥1 caffeinated beverage, they had later sleep onset that night and wake time the next morning than usual versus when they did not consume caffeine. Curbing caffeinated beverage consumption may aid in the maintenance of regular sleep schedules and advance sleep timing in adolescents.

Sleep during COVID-19-related school lockdown, a longitudinal study among high school students

There has been great concern about the impact of coronavirus disease 2019 (COVID-19)-related school lockdown on adolescent health. The aim of the present study was to compare sleep patterns before and during COVID-19-related school lockdown, in a large sample of high school students. The present study is based a prospective, longitudinal survey on adolescent sleep health. Phase 1 was conducted in 2019, whereas phase 2 was conducted in 2020 (response rate 60.2%), during the last 10 days of a 60-day long school lockdown. Main outcomes comprised sleep parameters from the Munich ChronoType Questionnaire (MCTQ). A total of 2,022 students provided valid responses to MCTQ in both survey phases. Results showed later sleep timing on schooldays in 2020 compared to 2019 (36 min later bedtimes, Cohen's d = 0.56; 1:35 hr later rise times, Cohen's d = 1.44). Time spent in bed on schooldays increased from 8:20 to 9:19 hr (Cohen's d = 0.78), and sleep duration increased by 45 min (Cohen's d = 0.49). The proportion of adolescents obtaining the recommended ≥8 hr of sleep on schooldays increased from 13.4% (2019) to 37.5% during the lockdown. Social jetlag was reduced from 2:37 hr (2019) to 1:53 hr (2020, Cohen's d = 0.59). Results points to a potential advantageous effect of school lockdown in terms of increased school day sleep duration and reduced social jetlag. As sleep is important for mental and somatic health, it is conceivable that increased sleep duration offered some protection against harmful aspects of the COVID-19 pandemic and associated social restrictions. Future studies should address possible associations between sleep changes and health during COVID-19-related school lockdown.

Associations of Sleep Insufficiency and Chronotype with Inflammatory Cytokines in College Students

PURPOSE

Sleep insufficiency and circadian rhythm disturbances in college students have become prominent. Current findings show that sleep insufficiency is closely related to inflammation. Studies on the correlation between chronotype and inflammatory factors are still lacking. Therefore, this research intended to examine the relationships between sleep duration, chronotype and inflammatory cytokines in young adults, and to estimate the correlation between chronotype and inflammatory cytokines stratified by sleep duration.

PATIENTS AND METHODS

We conducted a cross-sectional study in April and May 2019. Participants were recruited from two colleges located in central China. The Pittsburgh Sleep Quality Index (PSQI) and the Morning and Evening Questionnaire-5 (MEQ-5) were administered to assess sleep duration and chronotype. Sleep duration less than 7 hours was defined as insufficient sleep. Fasting venous blood was collected to measure plasma levels of inflammatory markers including IL-1β, IL-6, TNF-α and IL-10.

RESULTS

A total of 723 participants were included in this study, with a mean age of 18.68 years (standard deviation=0.99). After adjusting for confounding factors, the results of generalized linear model showed that sleep insufficiency was positively correlated with IL-1β, TNF-α and IL-10; and evening-types (E-types) were positively associated with the levels of IL-1β and IL-6 (p<0.05). Compared to the control group (sleep sufficiency and M-types), there were positive interaction effects of sleep insufficiency and neutral-types (N-types) on the levels of IL-1β, IL-6, TNF-α and IL-10 (p<0.05). The hierarchical regression model showed that N-types and E-types were positively correlated to the levels of IL-1β, IL-6, TNF-α and IL-10 among college students with sleep insufficiency (p<0.05).

CONCLUSION

The levels of inflammatory markers were higher among college students with sleep insufficiency and E-types. N-types and E-types were positively correlated with IL-1β, IL-6, TNF-α and IL-10 among college students with sleep insufficiency.