Circadian preference, sleep and daytime behaviour in adolescence

Are Owls and Larks Different When it Comes to Aggression? Genetics, Neurobiology, and Behavior

This review focuses on the contribution of circadian rhythms to aggression with a multifaceted approach incorporating genetics, neural networks, and behavior. We explore the hypothesis that chronic circadian misalignment is contributing to increased aggression. Genes involved in both circadian rhythms and aggression are discussed as a possible mechanism for increased aggression that might be elicited by circadian misalignment. We then discuss the neural networks underlying aggression and how dysregulation in the interaction of these networks evoked by circadian rhythm misalignment could contribute to aggression. The last section of this review will present recent human correlational data demonstrating the association between chronotype and/or circadian misalignment with aggression. With circadian rhythms and aggression being a burgeoning area of study, we hope that this review initiates more interest in this promising and topical area.

Circadian Phase Advances in Response to Weekend Morning Light in Adolescents With Short Sleep and Late Bedtimes on School Nights

Many adolescents fall asleep too late to get enough sleep (8-10 h) on school nights. Morning bright light advances circadian rhythms and could help adolescents fall asleep earlier. Morning bright light treatment before school, however, is difficult to fit into their morning schedule; weekends are more feasible. We examined phase advances in response to morning light treatment delivered over one weekend. Thirty-seven adolescents (16 males; 14.7-18.0 years) who reported short school-night sleep (≤7 h) and late bedtimes (school-nights ≥23:00; weekend/non-school nights ≥24:00) slept as usual at home for ∼2 weeks ("baseline") and then kept a fixed sleep schedule (baseline school-night bed and wake-up times ±30 min) for ∼1 week before living in the lab for one weekend. Sleep behavior was measured with wrist actigraphy and sleep diary. On Saturday morning, we woke each participant 1 h after his/her midpoint of baseline weekend/non-school night sleep and 1 h earlier on Sunday. They remained in dim room light (∼20 lux) or received 1.5 or 2.5 h of intermittent morning bright light (∼6000 lux) on both mornings. The dim light melatonin onset (DLMO), a phase marker of the circadian timing system, was measured on Friday and Sunday evenings to compute the weekend circadian phase shift. The dim room light and 1.5-h bright light groups advanced the same amount (0.6 ± 0.4 and 0.6 ± 0.5 h). The 2.5-h bright light group advanced 1.0 ± 0.4 h, which was significantly more than the other groups. These data suggest that it is possible to phase advance the circadian clock of adolescents who have late bedtimes and short school-night sleep in one weekend using light that begins shortly after their sleep midpoint.

The association between sleep chronotype and obesity among black and white participants of the Bogalusa Heart Study

Research indicates that sleep duration and quality are inter-related factors that contribute to obesity, but few studies have focused on sleep chronotype, representing an individual's circadian proclivity, nor assessed these factors in racially diverse middle-aged samples. We examined the associations between chronotype and obesity among black and white men and women participating in the Bogalusa Heart Study (BHS).Body mass index (BMI) and sleep data were available for 1,197 middle-aged men and women (mean age 48.2 ± 5.3 years) who participated in the BHS 2013-2016. Based on the reduced Morningness-Eveningness Questionnaire's cutoff values for chronotypes, we combined 'definitely morning' and 'moderately morning' types into 'morning' type, 'definitely evening' and 'moderately evening' types into 'evening' type and kept those who were "neither" type in a separate group. We used 'morning' type as the referent group. Obesity was defined as a BMI ≥ 30. Multivariable logistic regression models were used to examine associations adjusting for sex, age, education, smoking, alcohol use and drug use, depression, shift work, physical activity and sleep duration.Evening chronotype, reported by 11.1% of participants, was associated with obesity after multi-variable adjustment, including shift work, physical activity and sleep duration (OR 1.67, 95% CI: 1.08-2.56). However, once stratified by race (black/white), this association was found only among white participants (OR = 1.91, 95% CI = 1.12-3.25) after full adjustment.In our biracial, community-based population, evening chronotype was independently associated with obesity, specifically among white participants. Further research is needed to identify behavioral, endocrine, nutritional and genetic pathways which underlie these associations.

Assessing Chronotypes by Ambulatory Circadian Monitoring

In order to develop objective indexes for chronotype identification by means of direct measurement of circadian rhythms, 159 undergraduate students were recruited as volunteers and instructed to wear ambulatory circadian monitoring (ACM) sensors that continuously gathered information on the individual's environmental light and temperature exposure, wrist temperature, body position, activity, and the integrated TAP (temperature, activity, and position) variable for 7 consecutive days under regular free-living conditions. Among all the proposed indexes, the night phase marker (NPM) of the TAP variable was the best suited to discriminate among chronotypes, due to its relationship with the Munich ChronoType Questionnaire (β = 0.531; p < 0.001). The NPM of TAP allowed subjects to be classified as early- (E-type, 20%), neither- (N-type, 60%), and late-types (L-type, 20%), each of which had its own characteristics. In terms of light exposure, while all subjects had short exposure times to bright light (>100 lux), with a daily average of 93.84 ± 5.72 min, the earlier chronotypes were exposed to brighter days and darker nights compared to the later chronotypes. Furthermore, the earlier chronotypes were associated with higher stability and day-night contrast, along with an earlier phase, which could be the cause or consequence of the light exposure habits. Overall, these data support the use of ACM for chronotype identification and for evaluation under free living conditions, using objective markers.

The bidirectional association between sleep problems and anxiety symptoms in adolescents: a TRAILS report

BACKGROUND

Previous studies have suggested a bidirectional association between sleep problems and anxiety symptoms in adolescents. These studies used methods that do not separate between-person effects from within-person effects, and therefore their conclusions may not pertain to within-person mutual influences of sleep and anxiety. We examined bidirectional associations between sleep problems and anxiety during adolescence and young adulthood while differentiating between person effects from within-person effects.

METHODS

Data came from the Dutch TRacking Adolescents' Individual Lives Survey (TRAILS), a prospective cohort study including six waves of data spanning 15 years. Young adolescents (N = 2230, mean age at baseline 11.1 years) were followed every 2-3 years until young adulthood (mean age 25.6 years). Sleep problems and anxiety symptoms were measured by the Youth Self-Report, Adult Self-Report and Nottingham Health Profile. Temporal associations between sleep and anxiety were investigated using the random intercept cross-lagged panel model.

RESULTS

Across individuals, sleep problems were significantly associated with (β = 0.60, p < 0.001). At the within-person level, there were significant cross-sectional associations between sleep problems and anxiety symptoms at all waves (β = 0.12-0.34, p < 0.001). In addition, poor sleep predicted greater anxiety symptoms between the first and second, and between the third and fourth assessment wave. The reverse association was not statistically significant.

CONCLUSIONS

Within-person associations between sleep problems and anxiety are considerably weaker than between-person associations. Yet, our findings tentatively suggest that poor sleep, especially during early and mid-adolescence, may precede anxiety symptoms, and that anxiety might be prevented by alleviating sleep problems in young adolescents.

Chronotypes and its association with psychological morbidity and childhood parasomnias

BACKGROUND

The relationship between chronotypes and sleeping problems is not clear. The objective of the study was to identify the relative occurrence of chronotypes among college students and to explore adult psychological morbidity and childhood sleeping problems across chronotypes.

MATERIALS AND METHODS

One hundred and fifty undergraduate medical students were assigned into different chronotypes by Morningness-Eveningness Questionnaire and they were further assessed using Self-Reporting Questionnaire, Parasomnia Questionnaire (adapted from the Adult Sleep Disorders Questionnaire), and Pittsburgh Sleep Quality Index.

RESULTS

Intermediate chronotype was the most common, seen in 87 (58%) students, followed by evening type in 34 (22.7%). Evening types have more difficulties in making a decision, becoming exhausted more easily and feeling worthless than other chronotypes. Evening-oriented students showed a significantly higher frequency of initial insomnia and poorer overall sleep quality than the other groups. The current bedwetting was more in evening types; there was no difference in any other current and childhood parasomnias.

CONCLUSIONS

Evening chronotypes had greater difficulty in decision-making, and they were more vulnerable to feel worthless. No significant association was found between childhood parasomnias and chronotypes except persistent bedwetting during adulthood in evening types.

Chronotype, Social Jet Lag, and Cardiometabolic Risk Factors in Early Adolescence

IMPORTANCE

Inadequate sleep duration and quality increase the risk of obesity. Sleep timing, while less studied, is important in adolescents because increasing evening preferences (chronotypes), early school start times, and irregular sleep schedules may cause circadian misalignment.

OBJECTIVE

To investigate associations of chronotype and social jet lag with adiposity and cardiometabolic risk in young adolescents.

DESIGN, SETTING, AND PARTICIPANTS

Starting in 1999, Project Viva recruited pregnant women from eastern Massachusetts. Mother-child in-person visits occurred throughout childhood. From January 23, 2012, to October 16, 2016, 804 adolescents aged 12 to 17 years completed 5 days or more of wrist actigraphy, questionnaires, and anthropometric measurements. A cross-sectional analysis using these data was conducted from April 31, 2018, to May 1, 2019.

EXPOSURES

Chronotype, measured via a continuous scale with higher scores indicating greater evening preferences, and social jet lag, measured as the continuous difference in actigraphy sleep midpoint in hours from midnight on weekends vs weekdays, with higher values representing more delayed sleep timing on weekends.

MAIN OUTCOMES AND MEASURES

Adiposity, measured via anthropometry and dual-energy x-ray absorptiometry. For a subset of 479 adolescents with blood samples, cardiometabolic risk scores were computed as the mean of 5 sex- and cohort-specific z scores for waist circumference, systolic blood pressure, inversely scaled high-density lipoprotein cholesterol, and log-transformed triglycerides and homeostatic model of insulin resistance.

RESULTS

Among the 804 adolescents in the study, 418 were girls and 386 were boys, with a mean (SD) age of 13.2 (0.9) years. In multivariable models adjusted for age, puberty, season, and sociodemographics, associations of chronotype and social jet lag with adiposity varied by sex. For girls, greater evening preference was associated with a 0.58-cm (95% CI, 0.12-1.03 cm; P = .04 for interaction) higher waist circumference and 0.16 kg/m2 (95% CI, 0.01-0.31 kg/m2; P = .03 for interaction) higher fat mass index as measured by dual-energy x-ray absorptiometry; each hour of social jet lag was associated with a 1.19-cm (95% CI, 0.04-2.35 cm; P = .21 for interaction) higher waist circumference and 0.45 kg/m2 (95% CI, 0.09-0.82 kg/m2; P = .01 for interaction) higher fat mass index as measured by dual-energy x-ray absorptiometry. Associations of social jet lag and evening chronotypes persisted for many measures of adiposity after adjustment for sleep duration and other lifestyle behaviors. By contrast, no associations were observed in boys. There were no associations with the cardiometabolic risk score for either sex, although statistical power was low for this outcome.

CONCLUSIONS AND RELEVANCE

Evening chronotypes and social jet lag were associated with greater adiposity in adolescent girls but not adolescent boys. Interventions aimed at improving sleep schedules may be useful for obesity prevention, especially in girls.

Evening circadian preference is associated with sleep problems and daytime sleepiness in adolescents with ADHD

Adolescence is a developmental period characterized by disruptions in sleep and changes in circadian preferences. Although adolescents with attention-deficit/hyperactivity disorder (ADHD) are at even higher risk of sleep disruption than their peers, no study has examined whether circadian preference is associated with sleep problems and daytime sleepiness in adolescents with ADHD. This study provides an initial test of the hypothesis that greater evening preference would be associated with more sleep problems and daytime sleepiness in adolescents diagnosed with ADHD. Participants were 80 adolescents (69% male), aged 13-17 years, with ADHD. Adolescents completed measures assessing circadian preference, pubertal development, anxiety/depressive symptoms and weeknight sleep duration. Both adolescents and parents completed measures of sleep problems and daytime sleepiness. In regression analyses controlling for a number of other variables (i.e., age, sex, pubertal development, ADHD medication use, and ADHD, oppositional defiant disorder and internalizing symptom severity), greater evening preference was associated with both adolescent- and parent-reported sleep problems and daytime sleepiness. Greater evening preference remained significantly associated with each of these sleep problems and daytime sleepiness when also controlling for weeknight sleep duration. This is the first study to demonstrate that evening circadian preference is associated with both sleep problems and daytime sleepiness in adolescents with ADHD. The results indicate that it is important to consider circadian function as research examining sleep in adolescents with ADHD continues to advance.

Validation of the Chinese Version of the Children's ChronoType Questionnaire (CCTQ) in school-aged children

The Children's ChronoType Questionnaire (CCTQ) is a valid and reliable measure for assessing prepubertal children aged 4-11 years. The CCTQ is a parent-reported, 27-item questionnaire consisting of sleep-wake parameters for scheduled and free days (16 items), a morningness/eveningness scale (M/E, 10 items), and a five-point, single-item, chronotype score. The CCTQ has been translated into different languages, but a Chinese version is not available. In the present study, we aimed to produce a Chinese version of the CCTQ and test its validity and reliability on school-aged children. A total of 555 children aged 7-11 years were recruited from five primary schools. The parents were told to complete the CCTQ and record their child's sleep pattern in a 7-day sleep diary. Sixty-six children and their parents were invited to participate in determining the test-retest reliability of the CCTQ over a 2-week interval, and their sleep patterns were assessed using a sleep diary. The internal consistency of the Chinese CCTQ M/E score as measured by Cronbach's alpha was acceptable (0.74). Regarding the test-retest reliability of the instrument, moderate to strong Spearman's correlation coefficients were found for most of the CCTQ - sleep-wake items (ρ = 0.52-0.86) and for the CCTQ-M/E total score (ρ = 0.78). For the concurrent validity, Spearman's correlations between the sleep-wake parameters of the CCTQ and the sleep diary were moderate to high on both the scheduled days (ρ = 0.54 to 0.87) and free days (ρ = 0.36 to 0.60). For the correlations measured with actigraphs, significant correlations were found in the CCTQ sleep-wake parameters, including bedtime, get-up time, sleep latency, sleep period, time in bed, and mid-sleep point on both the scheduled (ρ = 0.31 to 0.76) and free days (ρ = 0.27 to 0.52), but not in sleep latency and sleep period on free days. The results of the present study suggest that the Chinese version of the CCTQ is a reliable and valid tool for assessing chronotypes in Chinese school-aged children in Hong Kong.

Childhood Trauma and Stressful Life Events Are Independently Associated with Sleep Disturbances in Adolescents

Adolescence is a critical developmental period associated with an increase in stress, the appearance of anxiety and depressive symptoms, and changes in sleep patterns. Even though the disruption of sleep patterns in stress and anxiety and depressive disorders is well known, the independent effects of childhood trauma and stressful life events on sleep patterns are less understood. We tested the independent effects of stress (childhood trauma and stressful life events) while controlling for anxiety and depression on adolescent sleep patterns. Seven hundred fifty-two adolescents (age 12-15 years) completed self-report questionnaires about childhood trauma, stressful life events, anxiety, and depression. Four sleep factors identifying movement during sleep, sleep regularity, sleep disturbances, and sleep pressure were extracted in the principal component analysis of sleep questions. Both childhood trauma and recent stressful life events were significantly associated with sleep disturbances before and after controlling for anxiety and depression.

Napping Behaviors and Extracurricular Club Activities in Japanese High School Students: Associations with Daytime Sleep Problems

Although engaging in evening naps and extracurricular activities are popular among Japanese high school students, the associations between these behaviors and daytime sleep problems were unclear. A questionnaire on daily life and sleeping habits was administered to 1314 high school students, aged between 15–17 years. The respondents were categorized by their after-school napping habits (did not nap, napped 1–2 days/week, napped ≥3 days/week), and their extracurricular activities (no activity, cultural club, athletic club). The mean nocturnal sleep duration on weekdays (± standard deviation (SD)) was 390 ± 56 min. This was significantly shorter in those students with a higher number of days/week spent napping (p < 0.001), and slightly longer for those in the athletic club (p < 0.001). Sleep problems—including subjective insufficient sleep, excessive sleepiness during class ≥3 days/week, and falling asleep during class ≥3 days/week—were reported by 64%, 55%, and 33% of respondents, respectively. A multiple logistic regression analysis showed significantly higher risks for excessive sleepiness among students taking naps ≥3 days/week, and who belonged to athletic clubs. In addition to those factors, students in cultural clubs revealed significantly higher risks for falling asleep during classes. Future studies are required to decrease daytime sleep problems associated with evening naps and extracurricular activities among high school students.

Effects of altitude on chronotype orientations in relation to cardiorespiratory and hematological quantities of college students in Ethiopia

BACKGROUND

The mechanism by which Ethiopians adapt to altitude is quite unique compared to other Highlanders with respect to increased oxygen saturation of hemoglobin. Although the effects of altitude on cardiorespiratory and hematological quantities on athletics performances are well known, but there is little information about its underlying effect on chronotype orientations.

METHODS

In this cross-sectional study 60 male college students with mean age 20±1.3 years from high and low altitude regions living in a tropical setting in Ethiopia were included. The participants' chronotype was determined using the self-administered Horne and Ostberg Morningness-Eveningness Questionnaires (MEQ). Measurements and estimations of hematological and cardiorespiratory parameters were performed from 7:00-9:00 AM, East African time zone, in order to minimize any variations that might occur in the course of the day. A multivariate binary logistic regression model was fitted to analyze the underlying chronotype predictors.

RESULTS

28 (93.9%) of participants from high altitude were mainly intermediate type (I-type) dominant with (MEQ = 42-58). While, 16 (55.2%) of participants from low altitudes were morning type (M-type) dominant chronotype with (MEQ = 59-69). Our main finding confirmed that altitude is an independent predictor of chronotype orientations of the participants (p<0.015). Thus, the results of the multivariate analysis seem to indicate that, participants from low and high altitudes may be uniquely oriented towards either M-type or I-type chronotype respectively (adjusted odds ratio [AOR] 4.772, 95% CI = 3.748-4618458). However, no significant difference on cardiorespiratory and hematological quantities between I-type and M-type chronotype of students from low altitude living in the same setting was reported (p > 0.05).

CONCLUSION

Our finding, reported for the first time that, the human chronotype varies according to the altitude, with no underlying effect of cardiorespiratory and hematological quantities.

Is improving sleep and circadian problems in adolescence a pathway to improved health? A mediation analysis

OBJECTIVE

The present study tested whether improvements in sleep and circadian problems mediate the effect of a novel transdiagnostic sleep and circadian intervention (TranS-C) on improvements in 5 health domains (emotional, cognitive, behavioral, social, and physical) in community-residing, evening chronotype adolescents who were at risk for problems in these 5 health domains.

METHOD

Participants were 176 adolescents (age mean [SD] = 14.77 [1.84] years; 58% female) who were randomized to receive 6 sessions of TranS-C or psychoeducation. Putative mediators tested were eveningness, weekday-weekend discrepancy in total sleep time and waketime, daytime sleepiness, Pittsburgh Sleep Quality Index score, and parent-reported sleep-wake problems. Risk in 5 health domains was measured using adolescent self-reported questionnaires, parent-reported Child Behavior Checklist, and ecological momentary assessment (EMA) of problems in the 5 health domains.

RESULTS

Reduced eveningness mediated the effects of TranS-C on reducing both self-reported and parent-reported risk in the 5 health domains. Reduction in daytime sleepiness mediated the effects of TranS-C on parent-reported risk in the 5 health domains. Reduction in parent-reported sleep-wake problems mediated the effects of TranS-C on self-reported, parent-reported, and EMA-assessed risk in the 5 health domains. Results did not support the other hypothesized mediators.

CONCLUSIONS

TranS-C exerts effects on reducing risk in multiple mental and physical health domains through reducing sleep and circadian problems in evening chronotype adolescents. Further research of TranS-C in other samples to assess its benefits for sleep and circadian problems as well as mental and physical health is warranted. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Associations of longitudinal sleep trajectories with risky sexual behavior during late adolescence

OBJECTIVE

The current study examines longitudinal sleep patterns in relation to risky sexual behaviors in a racially/ethnically diverse sample of adolescents.

METHOD

The sample comprises 1,850 youth (mean age at first wave = 16.21; 57% female). Sleep duration, sleep variability (difference between weekend and weekday sleep duration), and sleep quality were collected over four annual assessments from 2013 to 2017. Risky sexual behaviors (i.e., sex without condom use or sex after using drugs or alcohol) were examined at the fourth follow-up assessment when youth were 19 years old. Longitudinal latent class analysis characterized patterns of individual sleep dimensions over time, as well as the combination of sleep dimensions, and examined how emergent sleep classes associated with subsequent risky sexual behavior, after adjustment for sociodemographics and mental health.

RESULTS

After covariate adjustment, persistent "short" weekend sleepers were 2.2 times more likely to engage in risky sexual behaviors, compared to youth with sufficient weekend sleep duration. Contrary to expectations, adolescents with more consistent weekend/weekday sleep were 1.6-2 times more likely to engage in risky sexual behaviors, compared to those with greater variability; however, lack of variability may be an indicator of chronic insufficient sleep, both weekdays and weekends. There were no significant differences in risky sexual behavior according to classes of weekday sleep duration or quality. In the combined class model, those with persistently short and poor-quality sleep were at marginally greater risk for engaging in risky sexual behaviors.

CONCLUSION

Insufficient sleep in adolescents may increase risk for sexual risk-taking and may set the stage for accelerated health risk trajectories into adulthood. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Effect of exposure duration and light spectra on nighttime melatonin suppression in adolescents and adults

This study investigated how light exposure duration affects melatonin suppression, a well-established marker of circadian phase, and whether adolescents (13-18 years) are more sensitive to short-wavelength (blue) light than adults (32-51 years). Twenty-four participants (12 adolescents, 12 adults) were exposed to three lighting conditions during successive 4-h study nights that were separated by at least one week. In addition to a dim light (<5 lux) control, participants were exposed to two light spectra (warm (2700 K) and cool (5600 K)) delivering a circadian stimulus of 0.25 at eye level. Repeated measures analysis of variance revealed a significant main effect of exposure duration, indicating that a longer duration exposure suppressed melatonin to a greater degree. The analysis further revealed a significant main effect of spectrum and a significant interaction between spectrum and participant age. For the adolescents, but not the adults, melatonin suppression was significantly greater after exposure to the 5600 K intervention (43%) compared to the 2700 K intervention (29%), suggesting an increased sensitivity to short-wavelength radiation. These results will be used to extend the model of human circadian phototransduction to incorporate factors such as exposure duration and participant age to better predict effective circadian stimulus.

Chronotype mediates gender differences in risk propensity and risk-taking

Risk-taking is a complex form of decision-making that involves calculated assessments of potential costs and rewards that may be immediate or delayed. Thus, making predictions about inter-individual variation in risk-taking due to personality traits, decision styles or other attributes can be difficult. The association of risk-taking with gender is well-supported; males report higher propensity for risk-taking and show higher risk-taking on tasks measuring actual risk-taking behavior. Risk-taking also appears to be associated with circadian phenotypes (chronotypes), with evening-types reporting higher levels of risk-taking—but this association may be confounded by the fact that, in certain age groups, males are more likely to be evening-types. Here, we test for gender by chronotype effects on risk-taking in young adults (n = 610) using a self-reported risk propensity questionnaire, the health domain of the DOSPERT, and a behavioral task measuring risk-taking, the Balloon Analog Risk Task (BART). Our results show that males report and take significantly more risks than females in this population. In addition, evening-type individuals have significantly higher self-reported risk propensity and tend to take more risks on the BART. Interestingly, there is no significant difference in risk propensity or risk-taking behavior across male circadian phenotypes, but evening-type females significantly report and take more risk than female intermediate and morning types. In regression analyses, we found both gender and chronotype predict risk propensity and risk-taking. Path analysis confirms that chronotype has an indirect effect on gender differences in both risk propensity and risk-taking. Furthermore, we found that trait anxiety (STAI) and sleep disturbance (PROMIS), significantly correlate with chronotype and gender in the complete dataset, but do not independently predict differences in female risk-taking. These results suggest that chronotype mediates gender effects on risk-taking and that these effects are driven primarily by morning-type females, but are not related to gender-specific differences in trait anxiety or sleep quality.

Individual Differences in the Neural Basis of Response Inhibition After Sleep Deprivation Are Mediated by Chronotype

Sleep deprivation (SD) has been reported to severely affect executive function, and interindividual differences in these effects may contribute to the SD-associated cognition impairment. However, it is unclear how individual differences in chronotypes (morning-type, MT; evening-type, ET) influence neurobehavioral functions after SD. To address this question, we used functional magnetic resonance imaging (fMRI) to evaluate whether 24 h of SD differentially affect response inhibition, a core component of executive function, in MT and ET individuals. Accordingly, MT and ET participants were instructed to follow their preferred 7–9-h sleep schedule for 2 weeks at home both prior to and throughout the course of the study, and then performed a go/no-go task during fMRI scanning at 08:00 a.m. both at rested wakefulness (RW) and following SD. We also examined whether the neurobehavioral inhibition differences in the chronotypes in each session can be predicted by subjective ratings (sleepiness, mood, and task) or objective attention. Behaviorally, SD led to an increased response time of go trials (hit RT), more attentional lapses, higher subjective sleepiness, and worse mood indices, but it did not impair the accuracy of go trials (hit rate) and no-go trials (stop rate). Regardless of the presence of SD, ET individuals exhibited a lower stop rate, higher subjective ratings of sleepiness, exhausted mood, and task difficulty in comparison with MT individuals. On the neural level, SD resulted in decreased inhibition-related activation of the right lateral inferior frontal gyrus (rIFG) in MT individuals and increased rIFG activation in ET individuals. Moreover, the rIFG activation in ET individuals after SD was positively correlated to the subjective ratings of sleepiness and effort put into the task, which was considered as a compensatory response to the adverse effects of SD. These findings suggest that individual differences in inhibition-related cerebral activation after SD are influenced by chronotypes. In addition, ET individuals may be vulnerable to response inhibition. Thus, it is essential to take into consideration the chronotype in SD research and sleep medicine.

Resetting the late timing of 'night owls' has a positive impact on mental health and performance

BACKGROUND

There is conflict between living according to our endogenous biological rhythms and our external environment, with disruptions resulting in negative consequences to health and performance. This is often documented in shift work and jet lag, but 'societal norms' (eg, typical working hours) can create profound issues for 'night owls', people whose internal biological timing predisposes them to follow an unusually late sleep-wake cycle. Night owls have also been associated with health issues, mood disturbances, poorer performance and increased mortality rates.

METHODS

This study used a randomized control trial design aimed to shift the late timing of night owls to an earlier time (phase advance), using non-pharmacological, practical interventions in a real-world setting. These interventions targeted light exposure (through earlier wake up/sleep times), fixed meals times, caffeine intake and exercise.

RESULTS

Overall, participants demonstrated a significant advance of ∼2 h in sleep/wake timings as measured by actigraphy and circadian phase markers (dim light melatonin onset and peak time of the cortisol awakening response), whilst having no adverse effect on sleep duration. Notably, the phase advance was accompanied by significant improvements to self-reported depression and stress, as well as improved cognitive (reaction time) and physical (grip strength) performance measures during the typical 'suboptimal' morning hours.

CONCLUSIONS

Our findings propose a novel strategy for shifting clock timing towards a pattern that is more aligned to societal demands that could significantly improve elements of performance, mental health and sleep timing in the real world.

A composite measure of sleep health predicts concurrent mental and physical health outcomes in adolescents prone to eveningness

BACKGROUND

Sleep health can be characterized using multiple dimensions, including regularity, satisfaction, alertness, timing, efficiency, and duration. This study provides a preliminary derivation of a Sleep Health Composite score in adolescents with eveningness chronotype and examined its associations with mental and physical health outcomes.

METHODS

Participants were 176 adolescents (mean age 14.77 years, 58% female) who participated in a randomized controlled trial examining the Transdiagnostic Sleep and Circadian intervention. At study entry, the sample was characterized by evening circadian preference, later bedtime, and increased risk in 1 of 5 health domains (emotional, cognitive, behavioral, social, and physical). The Sleep Health Composite was derived using 7-day sleep diary and self-report rating scales. Each dimension was categorized as "good" or "poor" using cut-offs informed by prior studies and expert consensus. Mental and physical health outcomes were assessed using self-report rating scales, semistructured clinical interviews, parent report, or biometric measurement.

RESULTS

Sleep duration and satisfaction dimensions were most commonly rated as poor. Greater sleep health, as indexed by greater Sleep Health Composite score, was concurrently associated with lower risk in emotional, cognitive, and social domains, as well as fewer physical symptoms and reduced odds for obesity and current mood or anxiety disorders.

CONCLUSIONS

Sleep health is an important correlate of mental and physical health outcomes in adolescents. The Sleep Health Composite has potential application as an outcome measure in treatment studies of sleep and circadian problems.

Effect of White Light Devoid of "Cyan" Spectrum Radiation on Nighttime Melatonin Suppression Over a 1-h Exposure Duration

The intrinsically photosensitive retinal ganglion cells are the main conduit of the light signal emanating from the retina to the biological clock located in the suprachiasmatic nuclei of the hypothalamus. Lighting manufacturers are developing white light sources that are devoid of wavelengths around 480 nm ("cyan gap") to reduce their impact on the circadian system. The present study was designed to investigate whether exposure to a "cyan-gap," 3000 K white light source, spectrally tuned to reduce radiant power between 475 and 495 nm (reducing stimulation of the melanopsin-containing photoreceptor), would suppress melatonin less than a conventional 3000 K light source. The study's 2 phases employed a within-subjects experimental design involving the same 16 adult participants. In Phase 1, participants were exposed for 1 h to 3 experimental conditions over the course of 3 consecutive weeks: 1) dim light control (<5 lux at the eyes); 2) 800 lux at the eyes of a 3000 K light source; and 3) 800 lux at the eyes of a 3000 K, "cyan-gap" modified (3000 K mod) light source. The same protocol was repeated in Phase 2, but light levels were reduced to 400 lux at the eyes. As hypothesized, there were significant main effects of light level ( F_1,12 = 9.1, p < 0.05, η_p² = 0.43) and exposure duration ( F_1,12 = 47.7, p < 0.05, η_p² = 0.80) but there was no significant main effect of spectrum ( F_1,12 = 0.16, p > 0.05, η_p² = 0.01). There were no significant interactions with spectrum. Contrary to our model predictions, our results showed that short-term exposures (≤ 1 h) to "cyan-gap" light sources suppressed melatonin similarly to conventional light sources of the same CCT and photopic illuminance at the eyes.

Later Chronotype Is Associated with Higher Alcohol Consumption and More Adverse Childhood Experiences in Young Healthy Women

This study aimed at examining potential associations of mid sleep timing (chronotype) and social jetlag with intake of alcohol and caffeine, depressive symptoms, and body mass index (BMI) in a sample of healthy young women. Furthermore, it was explored whether these behavioral sleep–wake parameters are associated with adverse childhood experiences (ACEs). In total, 146 women (21.7 ± 1.7 years) took part in a two-week assessment on daily consumption of alcohol and caffeine. They completed questionnaires on ACEs, chronotype, sleep quality and depressive symptoms. Partial correlations and Chi-Square tests were calculated to assess the relationships between the assessed variables. Results show an association on a trend level for chronotype (r = 0.162, p = 0.053) and a significant association for social jetlag (r = 0.169, p = 0.044) with average alcohol intake. Furthermore, participants with above-median ACEs were more likely to be late chronotypes compared to the below-median group (X2(2) = 6.595, p = 0.037). We could replicate the association among late chronotype, social jetlag and higher alcohol consumption in a sample of healthy, young women. Furthermore, our results suggest a relationship between ACEs and chronotype. Although it can be hypothesized that it is rather ACEs that have an impact on chronotype, further research is needed to explore this relationship more and to shed more light on the direction of the association between chronotype and ACEs as well as on underlying mechanisms and possible mediators.

Internalizing symptoms and chronotype in youth: A longitudinal assessment of anxiety, depression and tripartite model

Biological rhythm theories highlight the reciprocal relations between dysregulated circadian patterns and internalizing psychopathology. Chronotype characterizes individuals' diurnal preference, as some exhibit more morningness or eveningness. Previous research suggests that eveningness prospectively predicts depression in adolescence. Anxiety often co-occurs with depression, but little is known about longitudinal, reciprocal associations between chronotype and anxiety, and whether this relationship remains after controlling for depression. We assessed different forms of anxiety (social, panic, separation), positive/negative affect, anxious arousal (from tripartite theory), and depression, in relation to chronotype to better understand the specificity and directionality of associations between chronotype and internalizing problems in adolescence. Community youth participated in three assessment time points: T1, T2 (18-months post-T1), and T3 (30-months post-T1) as part of a larger longitudinal study. Youth completed self-report measures of anxiety, depression, positive and negative affect, and chronotype. Regression analyses showed that eveningness: (1) concurrently associated with decreased separation anxiety, elevated symptoms of depression and low levels of positive affect, (2) was prospectively predicted by elevated depression, (3) did not predict later symptoms of anxiety. The reciprocal, prospective relationship between chronotype and internalizing psychopathology is specific to depression during adolescence.

Sex differences in sleep patterns and changes in 7th to 12th graders: a longitudinal follow-up study in Taiwan

Study Objectives

To assess the relationship between sex and the development of sleep patterns in adolescents from grade 7 to 12.

Methods

We analyzed longitudinal data from annual school-based assessments of sleep habits among secondary school students in northern Taiwan. Measures of sleep patterns included sleep length on weekdays and weekends as well as weekend-weekday difference (WndD), defined as the discrepancy in the time in bed (TIB) between weekdays and weekends. Growth curve models were used to assess sex differences in sleep patterns. Associations between other covariates and sleep patterns were also explored.

Results

We found shorter weekday TIB in girls compared with boys at all time points. In contrast, girls had longer weekend TIB than boys over time except in the 12th grade. WndD was also longer in girls than boys. All interaction terms between sex and time were insignificant, indicating that developmental change across time was not statistically different for boys and girls. Several other factors, namely, parental education, pubertal development, self-perceived health, weight status, depressive symptoms, academic stress, infrequent exercise, and substance use, were also found to be associated with sleep patterns.

Conclusions

Our findings show a sex difference in TIB both on weekdays and weekends. No sex difference was found in the development of sleep patterns over time.

Chronotype: Implications for Epidemiologic Studies on Chrono-Nutrition and Cardiometabolic Health

Chrono-nutrition is an emerging research field in nutritional epidemiology that encompasses 3 dimensions of eating behavior: timing, frequency, and regularity. To date, few studies have investigated how an individual's circadian typology, i.e., one's chronotype, affects the association between chrono-nutrition and cardiometabolic health. This review sets the directions for future research by providing a narrative overview of recent epidemiologic research on chronotype, its determinants, and its association with dietary intake and cardiometabolic health. Limited research was found on the association between chronotype and dietary intake in infants, children, and older adults. Moreover, most of the evidence in adolescents and adults was restricted to cross-sectional surveys with few longitudinal cohorts simultaneously collecting data on chronotype and dietary intake. There was a gap in the research concerning the association between chronotype and the 3 dimensions of chrono-nutrition. Whether chronotype modifies the association between diet and cardiometabolic health outcomes remains to be elucidated. In conclusion, further research is required to understand the interplay between chronotype, chrono-nutrition, and cardiometabolic health outcomes.

Preliminary support for the role of reward relevant effort and chronotype in the depression/insomnia comorbidity

BACKGROUND

The presence of insomnia in the context of depression is linked to a number of poor outcomes including reduced treatment response, increased likelihood of relapse, and greater functional impairment. Given the frequent co-occurrence of depression and insomnia, research into systems and processes relevant to both disorders, specifically reward processing and circadian rhythm disruption, may help parse this complex comorbidity.

METHODS

A pilot study was conducted on a sample of 10 veterans with clinically significant depression and insomnia symptoms. Participants completed objective (actigraphy) and subjective (sleep diary) assessments of sleep, self-reports of chronotype, and behavioral tasks assessing reward relevant effort before and after 6 sessions of Cognitive Behavioral Therapy for Insomnia.

RESULTS

Insomnia and depression significantly improved following CBT-I. Subjective sleep parameters significantly improved with large effect sizes. Actigraphy results were nonsignificant, but effect sizes for sleep efficiency and onset latency were in the medium range. Chronotype shifted significantly toward morningness following CBT-I, and an earlier chronotype at baseline was associated with increased reward effort following treatment. Changes in chronotype, depression and insomnia were not associated with changes in effort.

LIMITATIONS

Findings are limited by small sample size and lack of randomized control group.

CONCLUSIONS

Findings should be interpreted as hypothesis generating in the service of furthering research aimed at uncovering potential mechanisms underlying the depression/insomnia comorbidity. Analyses of sleep data in extant datasets of reward processing impairments in depression as well as original projects aimed at exploring potential sleep, circadian rhythm, and reward interactions in depression are encouraged.

The relationship between the development of social competence and sleep in infants: a longitudinal study

BACKGROUND

Many reports argue that sleep is important for children's health, learning, and academic performance. The purpose of this longitudinal study was to examine the association between sleep and the development of social competence in infants.

METHODS

This study was conducted as part of a Japan Science and Technology Agency (JST) project. Caregivers responded to the Japan Children's Study Sleep Questionnaire when children were 18 months old. The interactions of caregivers and children were observed when children were 18, 30, and 42 months old, and rated with the Interaction Rating Scale, which is a measure of social competence.

RESULTS

Nocturnal sleep duration of more than 10 h and an earlier bed time than 22:00 were significantly correlated with two trajectory groups (low point and high point transition groups) of children's social competence at 18, 30, and 42 months. Further, total sleep duration of more than 12.25 h and an earlier bed time than 22:00 were significantly correlated with the trajectory of children's social competence at 18, 30, and 42 months.

CONCLUSIONS

Sleep duration and sleep onset time are important factors in children's development of social competence.Trial registration The ethics committee of the JST approved this study on March 19, 2001. The registration number is 356-1.

Sleep Quantity and Problems as Mediators of the Eveningness-Adjustment Link during Childhood and Adolescence

Chronotype, or morningness/eveningness, has been associated with adjustment in both children and adolescents. Specifically, eveningness has been linked to adjustment difficulties; however, the mechanism underlying this association is poorly understood. The purpose of this study was to test whether the associations between eveningness and adjustment difficulties could be explained by an unfavorable impact of eveningness on sleep. Links from chronotype to internalizing problems and problem behaviors via sleep quantity and sleep problems were tested in a sample from the European Longitudinal Study of Pregnancy and Childhood (N = 3485; 48.8% female), both when the participants were children (7 years at T1, 11 at T2) and when they were adolescents (15 years at T1, 18 at T2). The findings provided evidence that eveningness predicted greater sleep problems and lower sleep quantity; however, only sleep problems predicted internalizing problems and problem behaviors. Sleep quantity did not mediate the eveningness-adjustment link, and sleep problems did so only in children. The findings show that sleep problems appear to be more important in explaining the eveningness-adjustment link rather than altered sleep quantity, commonly associated with eveningness.

Biological rhythm and emotional and behavioral problems among schoolchildren in Southern Brazil

Emotional and behavioral problems have been considered an indicative of mental disorder in children. Mental health problems affect 10-20% of children and adolescents living in low-income and middle-income countries. Evidence suggests that disruptions in the biological rhythm may be a primary cause of emotional and behavioral changes, which affects several psychological functions and moods. Thus, this study aimed at verifying the association between biological rhythm and emotional and behavioral problems in schoolchildren living in Southern Brazil. This is a cross-sectional study with a school-based sample conducted between August 2015 and November 2016. The presence of emotional and behavioral problems in children was verified by the Strengths and Difficulties Questionnaire (SDQ), parents' version. This is a 25-item assessment questionnaire used to screen mental health problems in children and adolescents (from 4 to 17 years of age) in the last 6 months. The Biological Rhythm Interview of Assessment in Neuropsychiatry-Kids (BRIAN-K) was used to measure the degree of biological rhythm disruption. The BRIAN-K consists of 20 items; from among these, 17 items are added to generate a quantitative measure, with greater scores indicating more biological rhythm disruption. The final score can also be divided into four subscales: sleep, social rhythm, eating pattern and overall activities. A total of 609 children responded to the assessment instruments. With regard to parents or primary caregiver, 596 completed the assessment and 13 (2%) were not located or refused to participate in the study. Thus, 596 dyads were included in the analysis. Children with emotional and behavioral problems presented higher scores in all domains of BRIAN-K: sleep, social, activity, eating pattern and total score (p < 0.001). The following variables remained associated with emotional and behavioral problems after adjusted analysis: BRIAN-K total score (p < 0.001) and all subscales sleep (p < 0.001), social (p < 0.001), activity (p < 0.001) and eating pattern (p < 0.001). Children with emotional and behavioral problems presented higher biological rhythm disruption when compared with children without emotional and behavioral problems. Our study emphasizes the importance of biological rhythm and its influence on emotional and behavioral problems in schoolchildren. Early detection of any biological rhythm disruption may enhance further assessment of any eventual emotional and behavioral problem and even a psychopathology.

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.

Eveningness diurnal preference associated with poorer socioemotional cognition and social functioning among healthy adolescents and young adults

Recently there has been growing interest in associations between sleep, emotion, and social functioning. Less is known about relationships between chronotype preference and socioemotional cognition and functioning, particularly among adolescents, who experience dramatic normative shifts in diurnal preference, affective functioning, and social competence. Fifty-five healthy adolescents and young adults completed a self-report chronotype preference measure, a computerized measure of socioemotional cognition, and a semi-structured clinical interview assessing interpersonal functioning. Greater eveningness preference was associated with poorer socioemotional cognition and social functioning in this age group. Future studies should assess these relationships across development and using objective measures of circadian timing.

Making Memories: Why Time Matters

In the last decade advances in human neuroscience have identified the critical importance of time in creating long-term memories. Circadian neuroscience has established biological time functions via cellular clocks regulated by photosensitive retinal ganglion cells and the suprachiasmatic nuclei. Individuals have different circadian clocks depending on their chronotypes that vary with genetic, age, and sex. In contrast, social time is determined by time zones, daylight savings time, and education and employment hours. Social time and circadian time differences can lead to circadian desynchronization, sleep deprivation, health problems, and poor cognitive performance. Synchronizing social time to circadian biology leads to better health and learning, as demonstrated in adolescent education. In-day making memories of complex bodies of structured information in education is organized in social time and uses many different learning techniques. Research in the neuroscience of long-term memory (LTM) has demonstrated in-day time spaced learning patterns of three repetitions of information separated by two rest periods are effective in making memories in mammals and humans. This time pattern is based on the intracellular processes required in synaptic plasticity. Circadian desynchronization, sleep deprivation, and memory consolidation in sleep are less well-understood, though there has been considerable progress in neuroscience research in the last decade. The interplay of circadian, in-day and sleep neuroscience research are creating an understanding of making memories in the first 24-h that has already led to interventions that can improve health and learning.

Effects of school time on sleep duration and sleepiness in adolescents

Delaying the time of start of school allows for longer sleep duration, better mood, and better school performance. In South Korea, a campaign was launched in 2014 to delay the school start time to 9 a.m. We analyzed the campaign’s effects on adolescents’ total sleep duration, sleepiness (presented as weekend catch-up sleep), emotions, and school performance. Based on data from 2013, changes of sleep patterns, emotions, and academic achievement in adolescents were evaluated using the 2012–2016 Korea Youth Risk Behavior Web-based survey from two educational districts: Gyeonggi (fully participated in the delayed school start time campaign; intervention group) and Daegu/Gyeongbuk/Ulsan (DGU, never participated; control group). The primary outcomes were sleep duration, time of sleep onset, and difference in sleep duration between weekdays and the weekend. Secondary outcomes were the proportional changes of mood, stress, and school performance. The sleep duration of students in the intervention group temporarily increased in 2015. However, because there was a simultaneous delay in time of sleep onset, sleep duration returned to pre-campaign levels in 2016. Although sleep duration did not increase, weekend catch-up sleep decreased by approximately 19 minutes for students in the intervention group. Meanwhile, in the control group sleep duration tended to decrease over the same period. The impact of the campaign on students' emotions and school performance could not be confirmed. This study demonstrated that delaying the school start time to 9 a.m. reduced duration of weekend catch-up sleep with a transient increase in sleep duration in adolescents.

Caffeinated Drinks Intake, Late Chronotype, and Increased Body Mass Index among Medical Students in Chongqing, China: A Multiple Mediation Model

Background: This paper investigates the problems regarding caffeinated drinks intake, late chronotype, and increased body mass index (BMI) among medical students at a Chinese university. Methods: This cross-sectional study was conducted in 2018 with 616 medical students from Chongqing Medical University in Chongqing, China, whose information were collected by a self-reported questionnaire that included four sections: Demographic characteristics; Caffeinated drinks intake and physical state; Morningness-Eveningness Questionnaire; Depression Anxiety Stress Scale 21. Multiple mediation analyses were conducted to test the impact of late chronotype on increased BMI through caffeinated drinks consumption through two models. Results: The significantly mediated effect of caffeinated drinks consumption was revealed (estimate: -0.01, SE = 0.01, 95% CI [-0.02, -0.01]), and which played a positive role in linking late chronotype (B = -0.01, SE = 0.01, p < 0.001) and increased BMI (B = 1.37, SE = 0.21, p < 0.01), but their significant association did not be found in reversed model. In addition, physical activity and inactivity times demonstrated significant indirect effects in the two models. Conclusions: Interventions should focus on reducing caffeinated drinks intake and sedentary behavior time, enhancing physical activity among medical students.