Adolescents' sleep in low-stress and high-stress (exam) times: a prospective quasi-experiment.

This prospective quasi-experiment (N = 175; mean age = 15.14 years) investigates changes in adolescents' sleep from low-stress (regular school week) to high-stress times (exam week), and examines the (moderating) role of chronic sleep reduction, baseline stress, and gender. Sleep was monitored over three consecutive weeks using actigraphy. Adolescents' sleep was more fragmented during the high-stress time than during the low-stress time, meaning that individuals slept more restless during stressful times. However, sleep efficiency, total sleep time, and sleep onset latency remained stable throughout the three consecutive weeks. High chronic sleep reduction was related to later bedtimes, later sleep start times, later sleep end times, later getting up times, and more time spent in bed. Furthermore, low chronic sleep reduction and high baseline stress levels were related to more fragmented sleep during stressful times. This study shows that stressful times can have negative effects on adolescents' sleep fragmentation, especially for adolescents with low chronic sleep reduction or high baseline stress levels.

The Chronic Sleep Reduction Questionnaire (CSRQ): a cross-cultural comparison and validation in Dutch and Australian adolescents.

Although adolescents often experience insufficient and/or poor sleep, sleep variables such as total sleep time do not account for individuals' sleep need and sleep debt and may therefore be an inadequate representation of adolescents' sleep problems and its daytime consequences. This problem can be overcome by using the Chronic Sleep Reduction Questionnaire (CSRQ), an assessment tool that measures symptoms of chronic sleep reduction and therefore accounting for sleep need and sleep debt. The present study aims at developing an English version of the CSRQ and assesses the reliability and validity of the Dutch and the English CSRQ version. The CSRQ was administered in large Dutch (n = 166, age = 15.2 ± 0.57 years, 28% male) and Australian (n = 236, age = 15.5 ± 0.99 years, 65% males) samples. Subjective sleep variables were measured with surveys and sleep diaries of five school nights. Additionally, sleep of the same five nights was monitored with actigraphy. Both CSRQ versions showed good psychometric properties concerning their reliability (Dutch: α = 0.85; English: α = 0.87) and validity as the same overall structure of the two CSRQ versions and significant correlations with subjective and objective sleep variables were found. School grades were related to chronic sleep reduction, whereas the relationship between grades and other sleep variables was weak or absent. These results highlight the idea that chronic sleep reduction may be a better indicator of adolescents' insufficient and/or poor sleep than other sleep variables such as total sleep time.

A cross-cultural comparison of sleep duration between US And Australian adolescents: the effect of school start time, parent-set bedtimes, and extracurricular load.

STUDY OBJECTIVE: To test whether sleep duration on school nights differs between adolescents in Australia and the United States and, if so, whether this difference is explained by cultural differences in school start time, parental involvement in setting bedtimes, and extracurricular commitments. PARTICIPANTS: Three hundred eighty-five adolescents aged 13 to 18 years (M = 15.57, SD = 0.95; 60% male) from Australia and 302 adolescents aged 13 to 19 years (M = 16.03, SD = 1.19; 35% male) from the United States. METHODS: Adolescents completed the School Sleep Habits Survey during class time, followed by an 8-day sleep diary. RESULTS: After controlling for age and gender, Australian adolescents obtained an average of 47 minutes more sleep per school night than those in the United States. Australian adolescents were more likely to have a parent-set bedtime (17.5% vs. 6.8%), have a later school start time (8:32 a.m. vs. 7:45 a.m.), and spend less time per day on extracurricular commitments (1 h 37 min vs. 2 h 41 min) than their U.S. peers. The mediating factors of parent-set bedtimes, later school start times, and less time spent on extracurricular activities were significantly associated with more total sleep. CONCLUSIONS: In addition to biological factors, extrinsic cultural factors significantly affect adolescent sleep. The present study highlights the importance of a cross-cultural, ecological approach and the impact of early school start times, lack of parental limit setting around bedtimes, and extracurricular load in limiting adolescent sleep.

The influence of sleep quality, sleep duration and sleepiness on school performance in children and adolescents: A meta-analytic review.

Insufficient sleep, poor sleep quality and sleepiness are common problems in children and adolescents being related to learning, memory and school performance. The associations between sleep quality (k=16 studies, N=13,631), sleep duration (k=17 studies, N=15,199), sleepiness (k=17, N=19,530) and school performance were examined in three separate meta-analyses including influential factors (e.g., gender, age, parameter assessment) as moderators. All three sleep variables were significantly but modestly related to school performance. Sleepiness showed the strongest relation to school performance (r=-0.133), followed by sleep quality (r=0.096) and sleep duration (r=0.069). Effect sizes were larger for studies including younger participants which can be explained by dramatic prefrontal cortex changes during (early) adolescence. Concerning the relationship between sleep duration and school performance age effects were even larger in studies that included more boys than in studies that included more girls, demonstrating the importance of differential pubertal development of boys and girls. Longitudinal and experimental studies are recommended in order to gain more insight into the different relationships and to develop programs that can improve school performance by changing individuals' sleep patterns.