Effects of sleep timing, sleep quality and sleep duration on school achievement in adolescents

Actigraphic sleep dimensions and associations with academic functioning among adolescents

STUDY OBJECTIVES

There is mixed evidence regarding associations of sleep duration with academic functioning in adolescents and a lack of research on other sleep dimensions, particularly using objective sleep measures. We examined associations of multiple actigraphic sleep dimensions with academic functioning among adolescents.

METHODS

Data were from the sleep sub-study of the age 15 wave of the Future of Families and Child Wellbeing Study (n = 774-782; 52% female), a national, diverse sample of teens. Adolescents wore wrist-actigraphs for ~1 week and completed a survey reporting academic performance and school-related behavioral problems. Regression models assessed whether average sleep duration, timing, maintenance efficiency, and SD-variability were associated with self-reported academic functioning in cross-sectional analyses adjusted for demographic characteristics, depressive symptoms, and anxious symptoms.

RESULTS

Later sleep timing (hours) and greater sleep variability (SD-hours) were associated with poorer academic outcomes, including sleep onset variability with higher odds of receiving a D or lower (OR = 1.29), sleep onset (β = -.07), sleep offset (β = -.08), and sleep duration variability (β = -.08) with fewer A grades, sleep offset with lower GPA (β = -.07), sleep offset (OR = 1.11), sleep duration variability (OR = 1.31), and sleep onset variability (OR = 1.42) with higher odds of being suspended or expelled in the past 2 years, and sleep duration variability with greater trouble at school (β = .13). Sleep duration, sleep maintenance efficiency, and sleep regularity index were not associated with academic functioning.

CONCLUSIONS

Later sleep timing and greater sleep variability are risk factors for certain academic problems among adolescents. Promoting sufficient, regular sleep timing across the week may improve adolescent academic functioning.

The Links Among Cumulative Ecological Risk and Smartphone Addiction, Sleep Quality in Chinese University Freshmen: A Two-Wave Study

Purpose

While previous research has highlighted the influence of family, school, and peer factors on smartphone addiction and sleep quality, the cumulative effects of these risk factors and their underlying causal relationships remain poorly understood. Therefore, based on the cumulative risk model and the bioecological model of human development, this study examined the longitudinal associations between cumulative ecological risk and smartphone addiction and sleep quality.

Methods

A survey was conducted among 653 Chinese university freshmen (mean age 18.56) at two distinct time points, with a 6-month interval. The initial assessment focused on family, school, and peer risk factors, while the subsequent assessment focused on smartphone addiction and sleep quality.

Results

Approximately 63.71% of university freshmen were found to be at risk of exposure. Compared to other risk-exposure groups, the group with no-risk exposure exhibited the lowest scores for smartphone addiction and sleep quality. The relationships between cumulative ecological risk and smartphone addiction and sleep quality displayed a linear pattern and a discernible "gradient effect". Smartphone addiction was identified as a fully mediating factor in the link between cumulative ecological risk and sleep quality, with a mediating effect value of 0.08 (representing 44.44% of the total effect).

Conclusion

University freshmen face various risks associated with their families, schools, and peers. The cumulative ecological risk can, directly and indirectly, impact sleep quality by influencing smartphone addiction. Given the observed "gradient effect" of cumulative ecological risk on smartphone addiction and sleep quality, it is imperative to adopt comprehensive risk prevention strategies to mitigate the impact of each risk factor.

Circadian preference and physical and cognitive performance in adolescence: A scoping review

Adolescence is a crucial period of development which coincides with changes in circadian rhythmicity. This may augment the impact of circadian preference on performance in this group. We aimed to scope the literature available on chronotypes and their effect on physical and mental aspects of performance in adolescents. Studies were identified by systematically searching bibliographical databases and grey literature. The Morningness-Eveningness Questionnaire was the most frequently reported tool for circadian preference assessment. Academic achievement was the most prevailing outcome, with evidence suggesting that morning type adolescents tend to outperform evening types, yet the results vary depending on multiple factors. Performance in tests of intelligence and executive functions was generally better at optimal times of the day (synchrony effect). Physical performance was examined in 8 studies, with very heterogeneous outcomes. Although the associations between circadian preference and performance in adolescents are evident in some areas, there are many factors that may be involved in the relationship and require further investigation. This review highlights the assessment of physical performance in relation to chronotypes, the multidimensional assessment of circadian preference, and the need for longitudinal studies as priorities for further research.Protocol: OSF Registration - Public registration, DOI: 10.17605/OSF.IO/UCA3Z.

Nighttime sleep duration and variability in children with obstructive sleep apnea syndrome: Sociodemographic disparities and neurobehavioral outcomes

OBJECTIVES

This study examined differences in sleep patterns by race, ethnicity, and socioeconomic status (SES) among children with Obstructive Sleep Apnea Syndrome (OSAS), and linkages between sleep patterns and neurobehavioral functioning.

METHOD

We used baseline data from the Childhood Adenotonsillectomy Study (CHAT), a multicenter, single-blind, randomized controlled trial designed to evaluate the efficacy of early adenotonsillectomy versus watchful waiting with supportive care for children with OSAS. Participants included children with OSAS (ages 5.0-9.9 years). SES indicators were obtained via questionnaire and geocoding (ArcGIS version 10.1). Caregivers and teachers reported on child inattention/impulsivity and executive functioning. Nighttime sleep duration and variability were measured using five-night sleep diaries.

RESULTS

Black children experienced shorter nighttime sleep duration than White children, by about 25 min, as well as greater sleep duration variability, while sleep duration was more variable in children of "other" racial and ethnic backgrounds versus White children. Of the socioeconomic correlates, only lower family income was associated with sleep duration variability. A short and more variable nighttime sleep duration were each associated with caregiver-rated child inattention and impulsivity. Greater sleep duration variability was linked to greater teacher-rated, but not caregiver-rated, executive functioning impairments.

CONCLUSIONS

Compared to White children with OSAS, Black children with OSAS experience a shorter and more variable nighttime sleep duration. Having a short and/or variable sleep duration may increase risk for neurobehavioral impairments in youth with OSAS, underscoring the potential benefits of sleep health promotion in the context of OSAS care.

The Social Side of Sleep: A Systematic Review of the Longitudinal Associations between Peer Relationships and Sleep Quality

In adolescence, peer relationships become crucial since youths start to rely on their peers for support. Thus, multiple facets of adolescents' well-being are affected by their peer relationships. In this vein, one of the central well-being aspects that could be affected by the peer relationships of adolescents is sleep quality. Nevertheless, it is still unclear how multiple peer relationship factors (i.e., positive, negative, emotional, and behavioral issues related to peer relationships) are intertwined with adolescents' sleep quality. For this reason, this systematic review with meta-analysis aims to summarize longitudinal studies to uncover how the interplay between peer relationship factors and adolescents' sleep quality unfolds over time. Nineteen longitudinal studies involving a total of 21,232 adolescents were included. Overall, findings from this review showed that (a) positive peer relationships and sleep quality were not associated over time; (b) negative peer relationships and sleep quality were bidirectionally associated over time; (c) few studies evaluated the bidirectional relations between emotional and behavioral issues and sleep quality, showing links with sleep schedule and duration, but not with sleep quality. Meta-analytic results were discussed, considering their implications.

A Weight and Meta-Analysis on the Academic Achievement of High School Students

Understanding the determinants of academic achievement (AA) is crucial for virtually every stakeholder interested in personal development and individual and societal wellbeing. Extensive research in several areas, such as education, economics, or psychology, has addressed this topic, identifying a vast number of determinants that impact high school students’ AA. In this work, we perform a meta-analysis, including a weight analysis of 49 quantitative studies that investigate this topic, exploring the best predictors of high school students’ academic success. We also explore moderation effects. Our results show that academic self-efficacy and socioeconomic status are the best predictors of AA, and they are statistically significant. Other statistically significant predictors, albeit less common in the analyses, are mastery avoidance, motivation, sleep habits, and work avoidance. Implications for theory and practice and directions for future research are discussed.

Need for cognition moderates the impairment of decision making caused by nightshift work in nurses

The current study explores the effect of nightshift work on the decision-making competence and performance of the Iowa Gambling Task (IGT) and analyzes whether individual differences in the need for cognition (NFC) can moderate this effect. A total of 107 female nurses were recruited to complete the decision-making competence scale and IGT at two times, after a night shift and after a day shift. The results revealed that the IGT scores and decision-making competence of nurses after nightshift work significantly declined, and also that the decrease in decision-making competence was related to the nurses’ performance of the IGT. Additionally, the decreasing degree of IGT and decision-making competence scores of the high-NFC group were significantly lower than those of the low-NFC group after nightshift work. In can be concluded that the decrease in decision-making competence which was related with poor decision-making due to nightshift work. NFC moderated the effect of nightshift work on decision-making.

Adolescent sleep health and school start times: Setting the research agenda for California and beyond: A research summit summary: A research summit summary

In fall 2019, California passed and signed into law SB328, the first US statewide legislation explicitly designed to protect adolescent sleep health by requiring most California public school districts to start no earlier than 8:00 AM for middle schools and 8:30 AM for high schools. Recognizing the unique opportunity presented by the bill's 3-year implementation period, a group of experts in adolescent sleep and school start times held a virtual summit on January 22-23, 2021 to (1) summarize the research on adolescent sleep and school start time change; (2) develop recommendations for relevant, refined, and innovative research areas and research questions; (3) provide input regarding research design, methodology, and implementation; and (4) offer a forum for networking, exchanging ideas, and establishing interdisciplinary research collaborations. Participants represented a multidisciplinary range of academic backgrounds including sleep and circadian biology, neuroscience, education, medicine, public health, mental health, safety, public policy, economics, implementation science, criminology, diversity studies, and science communication. This paper summarizes summit presentations regarding current knowledge on adolescent sleep health and school start times and key research recommendations from small group workshops on topics including research design and tools, methodological issues, sleep health disparities, logistical challenges in conducting school-based research, public-health impact, and novel and expanded approaches to research.

Circadian preference and academic achievement in school-aged students: a systematic review and a longitudinal investigation of reciprocal relations

We provide a systematic review of findings on the relation between circadian preference and school achievement published after the last comprehensive review in 2015. We further test this relation in a longitudinal study. Our review of 26 studies revealed a positive relation between morningness and students' school achievement, and a negative relation between eveningness and school achievement. In most studies, these relations were not affected by students' age, sex, or intelligence, but were significantly mediated by students' conscientiousness, motivation, and sleep behavior. Furthermore, circadian preference and school achievement showed no significant relation when school started in the afternoon. All studies were cross-sectional. Therefore, the direction of the relations between circadian preference, school achievement, and potential mediating variables like conscientiousness and motivation could not be investigated. In our longitudinal study, we tested the direction of the relations between circadian preference, academic achievement, conscientiousness, self-efficacy, and attitude toward school over time in a sample of 764 German high school students who were tested in the first (T1) and third (T2) year of high school. Findings from confirmatory cross-lagged models indicated reciprocal relations between circadian preference and school achievement: T1 morningness positively predicted change in grade point average over time while T1 grade point average positively predicted change in morningness and negatively predicted change in eveningness. Furthermore, T1 conscientiousness and T1 attitude toward school both positively predicted change in morningness, whereas T1 morningness and T1 eveningness did not significantly predict change in these variables.

Daily light exposure, sleep-wake cycle and attention in adolescents from different urban contexts

OBJECTIVE

to compare daily light exposure, activity-rest rhythm, sleep-wake cycle (SWC) and attention in Brazilian students living in different levels of urbanization.

METHODS

115 adolescents (74 girls), aged 14-18 years (mean 15.5 ± 0.7 years), from the first years of high school have participated. The SWC was evaluated by actimetry and a Sleep Diary for 10 days. Besides, the "Health and Sleep" Questionnaire, the Morningness and Eveningness Scale for adolescents, the Pittsburgh Sleep Quality Index, and the Pediatric Daytime Sleepiness Scale were answered. Attention was assessed by a Continuous Performance Task.

RESULTS

In the less urbanized region, there were a greater exposure to light during the day accompanied by a higher proportion of morning-types and less occurrence of excessive daytime sleepiness. Otherwise, in the more urbanized region, adolescents showed a trend to sleep less in weekdays and presented more irregularity in sleep duration between weekdays and weekend, with 83 ± 15% of sleep efficiency, 01:04 ± 1:30 h of WASO and 7 ± 6.7 awakenings per night on the weekdays, suggestive of poor sleep quality. Despite of this, they showed better attentional performance: more correct responses (tonic and phasic alertness, and sustained attention) and less omissions (for all components). Regardless of the degree of urbanization, there was partial sleep deprivation, irregular sleep schedules and poor sleep quality in adolescents.

CONCLUSIONS

The daily light exposure and activity-rest profiles, SWC and attention in adolescents varied according to the degree of urbanization. Besides, the negative impacts of early school starting times leading to sleep deprivation, irregular sleep times and poor sleep quality were observed irrespective of the degree of urbanization, reinforcing that the early school starting time at morning is a strong temporal challenge for teenagers, having negative impacts on cognition and academic performance.

Sleep behavior is associated with over two-fold decrease of sperm count in a chronotype-specific pattern: path analysis of 667 young men in the MARHCS study

Recent studies have shown that the reduction of sperm count is associated with sleep behaviors, including restricted/excessive sleep duration, late sleep time midpoint, and shift of sleep midpoint time (social jetlag). Chronotype is suggested to regulate sleep behaviors; however, the relationship between chronotype and human sperm count is unknown. The relationship between sleep behaviors and human sperm count, when sleep behaviors as well as chronotype are controlled is also unclear. We performed a path analysis of the data obtained from 667 Chinese men recruited into the MARHCS (Male Reproductive Health in Chongqing College Students) study. Chronotype, sleep duration, sleep time midpoint, and social jetlag were estimated by the Munich Chronotype Questionnaire. Sperm count was measured by computer-aided sperm analysis. The comprehensive relationship between chronotype, all sleep behaviors, and sperm count was tested by path analysis, in which the standardized residual of sperm count was used for adjustment of age, abstinence period, body mass index, tobacco smoking, alcohol drinking, and intake of tea, cola, and coffee. Our major findings are: (1) Chronotype negatively correlated with sleep duration (correlation coefficient (R) = -0.32, P < .001) and positively correlated with sleep midpoint (R = 0.65, P < .001) and social jetlag (R = 0.37, P < .001). (2) Sleep duration (U-shape transformed; R = -0.11, P = .005), sleep midpoint (R = -0.09, P = .021), and social jetlag (R = -0.12, P = .001), respectively, correlated with sperm count in univariate analysis. The relationship between sleep midpoint and sperm count disappeared when social jetlag was controlled. (3) Path analysis showed that chronotype is connected with sperm count through two pathways: via sleep duration (standardized path coefficient = -0.09, 95% CI: -0.17 to -0.01, P = .030) and via social jetlag (standardized path coefficient = -0.09, 95% CI: -0.17 to -0.01, P = .031). For men of earlier, intermediate, and later tertile of chronotype, the sleep-duration-related decrease of sperm count was separately estimated to be 16.3%, 12.8%, and 11.6%, while the social-jetlag-related decrease of sperm count was estimated to be 9.3%, 12.8%, and 19.2%. The total effect of sleep behaviors on sperm count was estimated to be 25.7%, 25.6%, and 30.7%, with an average of 27.4% for men of different chronotypes. The present study showed that men of earlier chronotype were prone to restricted/excessive sleep duration, while men of later chronotype were prone to social jetlag, both of which correlated with reduced sperm count, suggesting that chronotype may modulate the sleep behaviors and exert dual effects on sperm count via different sleep behaviors, leading to a ubiquitous sperm decline. Men of different chronotypes should take care to avoid different types of improper sleep behaviors, so as to prevent such deleterious effect on sperm count.

Insufficient sleep duration in association with self-reported pain and corresponding medicine use among adolescents: a cross-sectional population-based study in Latvia

OBJECTIVES

Pain among adolescents is prevalent that may negatively affect adolescents' general well-being of which sleep is an important domain. This study aims to explore the associations between weekly pain and medicine use for relevant pain and insufficient sleep duration among 11-, 13- and 15-year-old adolescents in Latvia by assessing the moderation effect of gender and age.

METHODS

Data from the Health Behaviour in School-aged Children Study on 2017/2018 of Latvia (n = 4412; 49.6% boys) were used. Logistic regression was applied to analyse the odds of insufficient sleep (< 7 h) on schooldays and weekends in association with weekly headache, stomach ache or backache and corresponding medicine use when testing the interaction effect of adolescents' gender and age.

RESULTS

The experience of weekly pain with or without medicine use significantly increased the odds of insufficient sleep compared to adolescents with pain less than weekly, while controlling for gender and age. The interaction effect of gender and age on the studied associations was not significant.

CONCLUSIONS

Weekly pain among adolescents is a significant risk factor for insufficient sleep duration, regardless of adolescents' gender and age.

Changes in sleep and activity from age 15 to 17 in students with traditional and college-style school schedules

OBJECTIVES

Sleep duration and physical activity decline with age during adolescence. Earlier school schedules may contribute to these declines. The aim of this longitudinal study was to track changes in sleep and activity of Icelandic youth from primary to secondary school and compare students who enrolled in secondary schools with traditional and college-style schedules.

METHODS

We measured free-living sleep and activity with wrist actigraphy and body composition by dual-energy x-ray absorptiometry in 145 students at age 15 and age 17, when 58% attended schools with college-style scheduling. Differences from 15 to 17 and between students of different school structures were assessed with mixed-effect models.

RESULTS

Actigraphs were worn for 7.1 ± 0.4 nights at 15 and 6.9 ± 0.4 nights at 17. Overall, sleep duration decreased from 6.6 ± 0.7 h/night to 6.2 ± 0.7 h/night from age 15 to 17 (P < .001). Students with traditional schedules reduced school-night sleep duration 26 min/night at follow-up (P< .001), while sleep duration did not change for college-style students. All students went to bed later on school nights at follow-up, but only college-style students rose later. Sleep efficiency and awakenings did not differ by schedule-type. Neither sex changed body fat percentage, but average school-day activity decreased by 19% (P< .001) on follow-up and did not differ by schedule-type.

CONCLUSIONS

Over the 2-year period, adolescents decreased weekly sleep duration and activity, but only those continuing traditional schedules reduced school-night sleep. This suggests greater individual control of school schedule may preserve sleep duration in this age group, which may be beneficial during the transition into adulthood.

Association between sleep-wake habits and use of health care services of middle-aged and elderly adults in China

OBJECTIVE

To examine the relationship between sleep-wake habits and the use of health care services.

RESULTS

The proportions of the participants who were "early to bed" and "late to bed" were 48.7% and 51.3%, respectively. In the full sample, compared with those who were early to bed and early to rise, participants who went to bed late were more likely to report physician visits (late to bed and early to rise: OR = 1.13, 95% CI: 1.08-1.19, late to bed and late to rise: OR = 1.27, 95% CI: 1.18-1.38, respectively). We found no significant association between sleep-wake habits and the number of hospitalization.

CONCLUSIONS

Those middle-aged and elderly people who stayed up late and got up late are more likely to visit the doctors than those who went to bed early and got up early.

METHODS

We obtained data from a cohort study of retired employees in China, and 36,601 (95.59%) involved in the present study. The participants were allocated into 4 sleep-wake habits groups: Early-bed/Early-rise, Early-bed/Late-rise, Late-bed/Early-rise, and Late-bed/Late-rise. We explored the association between sleep-wake habits with the number of physician visits and hospitalizations.

Development of Late Circadian Preference: Sleep Timing From Childhood to Late Adolescence

OBJECTIVES

To assess differences relating to circadian preference in objectively measured sleep patterns from childhood to adolescence over a 9-year period. We hypothesized there is developmental continuity in sleep timing and duration according to circadian preference.

STUDY DESIGN

Young participants (N = 111, 65% girls) from a community-based birth cohort underwent sleep actigraphy at mean ages 8.1 (SD = 0.3), 12.3 (SD = 0.5), and 16.9 (SD = 0.1) years. A short version of Morningness-Eveningness Questionnaire was administered in late adolescence. At each follow-up, sleep midpoint, duration, wake after sleep onset, sleep efficiency, and weekend catch-up sleep were compared between those reporting morning, intermediate, and evening preferences in late adolescence.

RESULTS

Mixed model analyses indicated that sleep timing was significantly earlier among morning types compared with evening types at all ages (P values < .04). The mean differences in sleep midpoint between morning and evening types increased from a mean of 19 minutes (age 8), 36 minutes (age 12), to 89 minutes (age 17). The largest change occurred from age 12 to 17 years. Sleep duration, wake after sleep onset, sleep efficiency, and catch-up sleep did not differ according to circadian preference.

CONCLUSIONS

This study found significant continuity in sleep timing from childhood to adolescence over 9 years, indicating that late circadian preference reported in late adolescence begins to manifest in middle childhood. Further studies are needed to establish whether sleep timing has its origins at an even earlier age.

Racial/ethnic sleep disparities in US school-aged children and adolescents: a review of the literature

Sleep is essential for optimal health, well-being, and cognitive functioning, and yet nationwide, youth are not obtaining consistent, adequate, or high-quality sleep. In fact, more than two-thirds of US adolescents are sleeping less than 8 hours nightly on school nights. Racial and ethnic minority children and adolescents are at an increased risk of having shorter sleep duration and poorer sleep quality than their white peers. In this review, we critically examined and compared results from 23 studies that have investigated racial/ethnic sleep disparities in American school-aged children and adolescents ages 6-19 years. We found that White youth generally had more sufficient sleep than minority youth, Hispanics had more than Blacks, and there was inconclusive evidence for Asians and other minorities. Recommendations for researchers include the following: (1) explore underlying causes of the disparities of these subpopulations, with a particular interest in identifying modifiable causes; (2) examine factors that may be impacted by racial/ethnic sleep disparities; (3) use a multidimensional approach to measuring sleep disparities; and (4) examine how beliefs about sleep are patterned by race/ethnicity. Understanding sleep disparities can inform interventions, policies, and educational programs to minimize sleep disparities and their impact on health, psychological, and educational outcomes.

Impact of Multi-Night Experimentally Induced Short Sleep on Adolescent Performance in a Simulated Classroom

Study Objectives

Investigate whether a realistic "dose" of shortened sleep, relative to a well-rested state, causes a decline in adolescents' learning and an increase in inattentive and sleepy behaviors in a simulated classroom setting.

Methods

Eighty-seven healthy 14.0- to 16.9-year olds underwent a 3-week sleep manipulation protocol, including two 5-night sleep manipulation conditions presented in a randomly counterbalanced within-subjects cross-over design. Wake time was held constant. Bedtimes were set to induce Short Sleep (SS; 6.5 hours in bed) versus Healthy Sleep (HS; 10 hours in bed). During the morning at the end of each condition, participants underwent a simulated classroom procedure in which they viewed lecture-based educational videotapes and completed relevant quizzes. Their behaviors in the simulated classroom were later coded by condition-blind raters for evidence of inattention and sleepiness.

Results

Adolescents had a longer average sleep period during HS (9.1 hours) than SS (6.5 hours). Compared to scores during HS, adolescents scored significantly lower on the quiz, showed more behaviors suggestive of inattention and sleepiness in the simulated classroom, and were reported by adolescents themselves and by their parents to be more inattentive and sleepy during SS. However, the impact of the manipulation on quiz scores was not mediated by changes in attention or sleepiness.

Conclusions

Although effect sizes were modest, these findings suggest that previously-reported correlations between sleep duration and academic performance reflect true cause-effect relationships. Findings add to the growing evidence that the chronically shortened sleep experienced by many adolescents on school nights adversely impacts their functioning and health.

Self-Regulation and Sleep Duration, Sleepiness, and Chronotype in Adolescents

OBJECTIVE

To determine whether shorter school-night sleep duration, greater daytime sleepiness, and greater eveningness chronotype were associated with lower self-regulation among adolescents.

METHODS

An online survey of 7th- to 12th-grade students in 19 schools in Fairfax County, Virginia Public Schools was conducted in 2015. Self-regulation was measured with the Behavior Rating Inventory of Executive Function, 2nd edition, Screening Self-Report Form. Sleep measures included school night-sleep duration (hours between usual bedtime and wake time), daytime sleepiness (Sleepiness Scale in the Sleep Habits Survey, tertiles), and chronotype (Morningness-Eveningness Scale for Children, continuous score and tertiles). Sociodemographic factors and mental health conditions were analyzed as potential confounders.

RESULTS

Among 2017 students surveyed, the mean age was 15.0 years (range, 12.1-18.9 years), and 21.7% slept <7 hours on school nights. In regression models adjusted for confounders, there was a significant independent association between self-regulation and both chronotype (P < .001) and daytime sleepiness (P < .001) but not sleep duration (P = .80). Compared with those in the lowest tertile of daytime sleepiness, those in the highest tertile had lower (0.59 SD units; 95% confidence interval, 0.48-0.71) self-regulation, as did those in the eveningness tertile of chronotype compared with those in the morningness tertile (0.35 SD units lower; 95% confidence interval, 0.24-0.46).

CONCLUSIONS

Among adolescents, greater daytime sleepiness and greater eveningness chronotype were independently associated with lower self-regulation, but shorter sleep duration was not. Aspects of sleep other than school-night sleep duration appear to be more strongly associated with self-regulation.

Associations between Neighborhood Context, Physical Activity, and Sleep in Adolescents

OBJECTIVE

This study examined how neighborhood access to recreation facilities and physical activity are linked to multiple indices of adolescent sleep. Physical activity was also assessed as a mediator of the association between access to recreation facilities and sleep.

DESIGN

The study used a cross-sectional design and path modeling analysis techniques.

SETTING

Participants were recruited from small towns and semi-rural communities in Alabama.

PARTICIPANTS

Participants were 231 adolescents (55% female) with an average age of 16.75 years (SD = .81). Sixty-seven percent of the youth were European American and 33% were African American. The sample was socioeconomically diverse with more than a third of participants living at or below the poverty line and less than half from middle class families.

MEASUREMENTS

Adolescent neighborhood access to recreation facilities and physical activity were assessed via self-report. Sleep minutes, efficiency, and schedule were measured using actigraphy.

RESULTS

Access to recreation facilities was associated with more sleep minutes and later morning wake time, as well as a trend towards increased sleep efficiency. Access to recreation facilities was also linked to more physical activity, and physical activity was related to more sleep minutes, later wake time, and less wake time variability. Physical activity was a mediating and intervening link between access to recreation facilities and these sleep parameters.

CONCLUSIONS

Findings implicate physical activity as one mechanism linking neighborhood context to adolescent sleep. The results suggest that establishing more neighborhood opportunities for physical activity may have cascading effects on multiple aspects of adolescent physical health.

Tailored Lighting Intervention for Persons with Dementia and Caregivers Living at Home

OBJECTIVES

Light therapy has shown promise as a nonpharmacological treatment to help regulate abnormal sleep-wake patterns and associated behavioral issues prevalent among individuals diagnosed with Alzheimer's disease and related dementia (ADRD). The present study investigated the effectiveness of a lighting intervention designed to increase circadian stimulation during the day using light sources that have high short-wavelength content and high light output.

METHODS

Thirty-five persons with ADRD and 34 caregivers completed the 11-week study. During week 1, subjective questionnaires were administered to the study participants. During week 2, baseline data were collected using Daysimeters and actigraphs. Researchers installed the lighting during week 3, followed by 4 weeks of the tailored lighting intervention. During the last week of the lighting intervention, Daysimeter, actigraph and questionnaire data were again collected. Three weeks after the lighting intervention was removed, a third data collection (post-intervention assessment) was performed.

RESULTS

The lighting intervention significantly increased circadian entrainment, as measured by phasor magnitude and sleep efficiency, as measured by actigraphy data, and significantly reduced symptoms of depression in the participants with ADRD. The caregivers also exhibited an increase in circadian entrainment during the lighting intervention; a seasonal effect of greater sleep efficiency and longer sleep duration was also found for caregivers.

CONCLUSIONS

An ambient lighting intervention designed to increase daytime circadian stimulation can be used to increase sleep efficiency in persons with ADRD and their caregivers, and may also be effective for other populations such as healthy older adults with sleep problems, adolescents, and veterans with traumatic brain injury.