Preliminary evidence that misalignment between sleep and circadian timing alters risk-taking preferences.

Decision-making has been shown to suffer when circadian preference is misaligned with time of assessment; however, little is known about how misalignment between sleep timing and the central circadian clock impacts decision-making. This study captured naturally occurring variation in circadian alignment (i.e., alignment of sleep-wake timing with the central circadian clock) to examine if greater misalignment predicts worse decision-making. Over the course of 2 weeks, 32 late adolescent drinkers (aged 18-22 years; 61% female; 69% White) continuously wore actigraphs and completed two overnight in-laboratory visits (Thursday and Sunday) in which both dim-light melatonin onset (DLMO) and behavioural decision-making (risk taking, framing, and strategic reasoning tasks) were assessed. Sleep-wake timing was assessed by actigraphic midsleep from the 2 nights prior to each in-laboratory visit. Alignment was operationalised as the phase angle (interval) between average DLMO and average midsleep. Multilevel modelling was used to predict performance on decision-making tasks from circadian alignment during each in-laboratory visit; non-linear associations were also examined. Shorter DLMO-midsleep phase angle predicted greater risk-taking under conditions of potential loss (B = -0.11, p = 0.06), but less risk-taking under conditions of potential reward (B = 0.14, p = 0.03) in a curvilinear fashion. Misalignment did not predict outcomes in the framing and strategic reasoning tasks. Findings suggest that shorter alignment in timing of sleep with the central circadian clock (e.g., phase-delayed misalignment) may impact risky decision-making, further extending accumulating evidence that sleep/circadian factors are tied to risk-taking. Future studies will need to replicate findings and experimentally probe whether manipulating alignment influences decision-making.

The 24-hour rhythm in alcohol craving and individual differences in sleep characteristics and alcohol use frequency.

BACKGROUND: Evidence implicates sleep/circadian factors in alcohol use, suggesting the existence of a 24-h rhythm in alcohol craving, which may vary by individual differences in sleep factors and alcohol use frequency. This study sought to (1) replicate prior findings of a 24-h rhythm in alcohol craving, and (2) examine whether individual differences in sleep timing, sleep duration, or alcohol use frequency are related to differences in the timing of the peak of the craving rhythm (i.e., the acrophase) or magnitude of fluctuation of the rhythm (i.e., amplitude). Finally, whether such associations varied by sex or racial identity was explored. METHODS: Two-hundred fifteen adult drinkers (21 to 35 years of age, 72% male, 66% self-identified as White) completed a baseline assessment of alcohol use frequency and then smartphone reports of alcohol craving intensity six times a day across 10 days. Sleep timing was also recorded each morning of the 10-day period. Multilevel cosinor analysis was used to test the presence of a 24-h rhythm and to estimate acrophase and amplitude. RESULTS: Multilevel cosinor analysis revealed a 24-h rhythm in alcohol craving. Individual differences in sleep timing or sleep duration did not predict rhythm acrophase or amplitude. However, alcohol use frequency moderated this rhythm wherein individuals who used alcohol more frequently in the 30 days prior to beginning the study had higher mean levels of craving and greater rhythm amplitudes (i.e., greater rhythmic fluctuations). Associations did not vary by sex or racial identity. CONCLUSIONS: Results show that alcohol craving exhibits a systematic rhythm over the course of the 24 h and that the frequency of alcohol use may be relevant to the shape of this rhythm. Consideration of daily rhythms in alcohol craving may further our understanding of the mechanisms that drive alcohol use.

Associations Between Adolescent Depression and Self-Harm Behaviors and Screen Media Use in a Nationally Representative Time-Diary Study.

Screen media use is associated with mental health problems among adolescents. However, few studies have examined screen media use using contemporaneous time diaries (rather than retrospective reports), compared associations across specific screen media activities or by gender, or examined associations with self-harm behaviors. Participants were 13- to 15-year-old adolescents completing time diaries (n = 4,252) for one weekday and one weekend day in the 2015 administration of the Millennium Cohort Study, a nationally representative birth cohort study of UK adolescents. Participants also completed a measure of depressive symptoms and reported whether they had engaged in self-harm in the last year. Girls who spent 2 + hrs/day, compared to < 2 h/day, on digital media were more likely to self-harm (for social media use, adjusted relative risk [ARR] for self-harm = 1.46, 95% CI = 1.17, 1.82; for internet use, ARR = 1.80 [1.20, 2.70]). Girls spending more time on digital media were also more likely to be depressed (for social media, ARR = 1.29 [1.03, 1.63]; for internet use, ARR = 1.75 [1.19, 2.59]). Associations with gaming, texting/e-mailing, and TV/video watching among girls were mostly not significant. Associations for boys were mostly not significant. Girls who use digital media (especially social media and the internet) more hrs/day are more likely to have clinically significant levels of depressive symptoms and prior history of self-harm, though gaming, texting/e-mailing, and TV/video watching showed few associations. Screen media use was mostly not significantly associated with self-harm or depression among boys.

Sleep characteristics of U.S. adults before and during the COVID-19 pandemic.

RATIONALE: Understanding how health has changed in response to the COVID-19 pandemic is critical to recovering from the pandemic. OBJECTIVE: This study focused on how sleep characteristics in the United States may be different from before to during the COVID-19 pandemic. METHODS: To this end, the sleep characteristics of a nationally representative sample of U.S. adults collected before the COVID-19 outbreak (i.e., 2018 National Health Interview Survey, n = 19,433) were compared to the sleep characteristics of a nationally representative sample of U.S. adults recruited via Luc.id, an online survey sampling company, during the COVID-19 outbreak (i.e., 2020 Luc.id, n = 2059). RESULTS: While average sleep duration did not change between 2018 and 2020, the prevalence of both shorter and longer than recommended sleep duration were greater in 2020. Moreover, the number of days with difficulty falling asleep, difficulty staying asleep, and not feeling rested was greater in 2020 than 2018. Adults younger than 60 had larger differences than those 60 or older. CONCLUSIONS: Sleep health in U.S. adults was worse in 2020 than in 2018, particularly in adults younger than 60. Findings highlight sleep as target in future research and interventions seeking to understand and reduce the effects of the COVID-19 pandemic.

Is there a 24-hour rhythm in alcohol craving and does it vary by sleep/circadian timing?

Increasing evidence implicates sleep/circadian factors in alcohol use; however, the role of such factors in alcohol craving has received scant attention. Prior research suggests a 24-hour rhythm in related processes (e.g., reward motivation), but more research directly investigating a rhythm in craving is needed. Moreover, prior evidence is ambiguous whether such a rhythm in alcohol craving may vary by sleep/circadian timing. To examine these possibilities, 36 late adolescents (18-22 years of age; 61% female) with regular alcohol use but without a current alcohol use disorder were recruited to complete smartphone reports of alcohol craving intensity six times a day for two weeks. During these two weeks, participants wore wrist actigraphs and completed two in-lab assessments (on Thursday and Sunday) of dim light melatonin onset (DLMO). Average actigraphically derived midpoint of sleep on weekends and average DLMO were used as indicators of sleep and circadian timing, respectively. Multilevel cosinor analysis revealed a 24-hour rhythm in alcohol craving. Findings across the sleep and circadian timing variables converged to suggest that sleep/circadian timing moderated the 24-hour rhythm in alcohol craving. Specifically, people with later sleep/circadian timing had later timing of peak alcohol craving. These findings add to the growing evidence of potential circadian influences on reward-related phenomena and suggest that greater consideration of sleep and circadian influences on alcohol craving may be useful for understanding alcohol use patterns and advancing related interventions.

Screen media use and sleep disturbance symptom severity in children.

OBJECTIVES: Few studies have sought to evaluate how screen media use relates to symptoms of sleep-wake disturbances. To extend these prior studies in a large sample of children, this study examined associations of different types of screen media with symptom severity of different classes of sleep-wake disturbances. This study was preregistered here. DESIGN: This study utilized the baseline cross-sectional survey administered within the Adolescent Brain Cognitive Development Study (ABCD; Release 2.0). PARTICIPANTS: ABCD recruited over 11,000 U.S. children age 9-10 across 21 study sites using an epidemiologically-informed school-based recruitment strategy. MEASUREMENTS: Children reported typical weekend and weekday use of TV, video, video game, social media, texting, and video chat, and parents completed reports of the child's symptom severity of sleep-wake disturbances via the Sleep Disturbance Scale for Children. RESULTS: Greater screen media use, TV, video, and video game use, was associated with decreased sleep duration, increased sleep onset latency as well as greater excessive sleepiness, insomnia, and overall sleep disturbance symptom severity. Use of these screen medias were also associated with clinically relevant sleep problems. Ethnoracial differences emerged in screen use and sleep, but did not moderate the association between screen use and sleep. CONCLUSIONS: Greater use of screen medias was not just associated with longer sleep onset latency and shorter sleep duration, but also increased severity of multiple types of sleep-wake disturbances. Future research should use longitudinal designs to determine the direction of these associations in adolescent populations.

Changes in sleep difficulties among the U.S. population from 2013 to 2017: results from the National Health Interview Survey.

OBJECTIVES: This study sought to evaluate how sleep difficulties have changed over time and to evaluate if these changes relate to changes in sleep duration. DESIGN: National Health Interview Survey administered annually from 2013 to 2017 by the National Center for Health Statistics. SETTING: U.S. national adult population. PARTICIPANTS: 164,696 U.S. adults sampled across the nation using multistage area probability design. MEASUREMENTS: Self-reports of difficulties falling asleep, trouble staying asleep, use of sleep medication, feelings of restorative sleep, and sleep duration collected each year. RESULTS: From 2013 to 2017, the prevalence of reporting any days with difficulty falling asleep (B = .01, p <.01), trouble staying asleep (B = .02, p < .001), increased, yet waking feeling rested also increased (B = .01, p = .004), while average sleep duration decreased (B = -.02, p < .001). Moreover, changes in these sleep difficulties were independent of sleep duration and primarily occurred in healthy sleepers. CONCLUSIONS: Multiple aspects of sleep difficulties show an undesirable trajectory in the U.S. adult population. Moreover, these trends appear to be independent of sleep duration and are primarily occurring in healthy sleepers. Future research should simultaneously consider how multiple aspects of sleep are changing and further examine the sources of these changes.

Associations between screen time and sleep duration are primarily driven by portable electronic devices: evidence from a population-based study of U.S. children ages 0-17.

STUDY OBJECTIVES: Excessive screen time in child and adolescent populations is associated with short sleep duration, but the unique effects of portable vs. non-portable electronic devices has received little attention. Moreover, it is unknown whether the effects of these devices change across childhood. To address these gaps, the current study compared the association of portable vs. non-portable electronic devices with sleep duration throughout childhood. METHODS: Data were from a 2016 national survey of the caregivers of 43,755 children and adolescents ages 0-17 administered by the U.S. Census Bureau. RESULTS: Children and adolescents who spent more time on screens slept fewer hours and were more likely to get insufficient sleep. In multivariate regressions including time spent on TV and video game consoles and portable electronic devices, associations with sleep duration were primarily due to portable electronic devices. These results remained when demographic variables, diagnoses of anxiety or depression, physical activity, and BMI were included in the model. Moreover, time spent using both portable and non-portable devices was important for sleep duration in children under age 10, but the importance of non-portable devices diminished in children over 10. CONCLUSIONS: Spending multiple hours a day on electronic devices is associated with shorter sleep duration across all ages. However, portable electronic devices have a stronger association with sleep duration than non-portable electronic screens, with non-portable devices less relevant for sleep duration in children over age 10. The findings suggest that future interventions should uniquely target portable electronic devices while also accounting for the age group of children targeted.

Does Stress Explain the Effect of Sleep on Self-Control Difficulties? A Month-Long Daily Diary Study.

Insufficient sleep is linked to increased stress and suboptimal self-control; however, no studies have examined stress as a reason for why sleep affects self-control. Moreover, it is unknown if there are individual differences that make people vulnerable to this dynamic. Daily diary entries from 212 university students across 30 days were used in a multilevel path model examining if stress explained how prior night sleep affected next-day self-control difficulties and exploring if individual differences in sleep duration, stress, or self-control qualified this effect. Increased stress partially mediated of the effect of reduced sleep duration on increased next-day self-control difficulty. Moreover, short sleep increased next-day stress more for individuals with higher typical stress. Daytime stress especially amplified self-control difficulty for individuals with shorter typical sleep duration. Findings implicate stress as a substantial factor in how sleep loss undermines self-control and identify individuals particularly susceptible to this effect.

Does sleep partially mediate the effect of everyday discrimination on future mental and physical health?

OBJECTIVE: The current study examined whether sleep mediates the effect of discrimination experiences on mental and physical health over time. Prior research suggests a partially mediated relation; however, these studies used cross-sectional designs which provide insufficient causal evidence. METHOD: The study used longitudinal data available from the Midlife in the United States Study (MIDUS II, Biomarker project, and MIDUS III) applying structural equation modeling to evaluate whether self-reported sleep (N = 866) mediated the impact of discrimination on mental and physical health outcomes. RESULTS: Self-reported sleep quality partially mediated the effect of discrimination on mental and physical health. Analyses also indicated self-reported daytime dysfunction (i.e., difficulties maintaining alertness and motivation during the day) as a key component of sleep that mediates the discrimination and mental and physical health relations. Interestingly, having multiple marginalized identities did not amplify the impact of discrimination on sleep and health. CONCLUSIONS: These findings build upon previous cross-sectional research by better supporting the causal assertion that experiences of discrimination undermine sleep, which in turn worsens both mental and physical health. Altogether, results underscore the harmful impact of discrimination on health indirectly through sleep and offer insight into directions for future research.

Individual Differences in Diurnal Preference and Time-of-Exercise Interact to Predict Exercise Frequency.

BACKGROUND: Diurnal preference (and chronotype more generally) has been implicated in exercise behavior, but this relation has not been examined using objective exercise measurements nor have potential psychosocial mediators been examined. Furthermore, time-of-day often moderates diurnal preference's influence on outcomes, and it is unknown whether time-of-exercise may influence the relation between chronotype and exercise frequency. PURPOSE: The current study examined whether individual differences in diurnal preference ("morningness-eveningness") predict unique variance in exercise frequency and if commonly studied psychosocial variables mediate this relation (i.e., behavioral intentions, internal exercise control, external exercise control, and conscientiousness). Moreover, the study sought to test whether individuals' typical time-of-exercise moderated the impact of diurnal preference on exercise frequency. METHODS: One hundred twelve healthy adults (mean age = 25.4; SD = 11.6 years) completed baseline demographics and then wore Fitbit Zips® for 4 weeks to objectively measure exercise frequency and typical time-of-exercise. At the end of the study, participants also self-reported recent exercise. RESULTS: Diurnal preference predicted both self-reported exercise and Fitbit-recorded exercise frequency. When evaluating mediators, only conscientiousness emerged as a partial mediator of the relation between diurnal preference and self-reported exercise. In addition, time-of-exercise moderated diurnal preference's relation to both self-reported exercise and Fitbit-recorded exercise frequency such that diurnal preference predicted higher exercise frequency when exercise occurred at a time that was congruent with one's diurnal preference. CONCLUSION: Based on these findings, diurnal preference is valuable, above and beyond other psychological constructs, in predicting exercise frequency and represents an important variable to incorporate into interventions seeking to increase exercise.