Feasibility and impact on daytime sleepiness of an experimental protocol inducing variable sleep duration in adolescents.

Although most research on sleep and adolescent health has focused on how long each youth sleeps on average, variability in sleep duration may be just as problematic. Existing findings have been inconsistent and unable to address cause-effect relationships. This study piloted an experimental protocol to induce sleep variability and explore its impact on daytime sleepiness in adolescents. Healthy adolescents aged 14-17 participated in a 3-week, at-home protocol. Sleep was monitored by sleep diaries and actigraphy. Following a run-in period to stabilize wake times (set at 6:30am throughout the protocol), participants were randomly counterbalanced across two 5-night experimental conditions. Bedtimes were consistent at 11:00pm during the stable sleep condition (7.5-hour sleep period each night) but changed on alternating nights during the variable sleep condition (ranging from 9:30pm to 12:30am) so that sleep duration averaged 7.5 hours across the condition with a standard deviation of 1.37 hours. Difficulty waking was assessed each morning and daytime sleepiness was assessed by end-of-condition parent- and adolescent-reports. Of the 20 participants who completed the study, 16 met the predetermined adherence definition. For those who were adherent, there were no differences in overall sleep duration between the stable and variable sleep conditions (p>.05) but adolescents had 58.6 minutes greater night-to-night variation in sleep duration in the variable condition (p < .001). Across all nights, youth reported greater difficulty waking following nights of shorter assigned sleep (p = .004) and greater overall sleepiness during the variable condition (p = .03). It is feasible to experimentally vary how long adolescents sleep on a nightly basis while holding average sleep duration constant. Such a protocol will promote tests of the acute effects of day-to-day changes in sleep duration on health.

Inducing more sleep on school nights reduces sedentary behavior without affecting physical activity in short-sleeping adolescents.

OBJECTIVES/BACKGROUND: Short sleep duration during adolescence is associated with increased dietary intake and greater risk for overweight/obesity. However, findings are mixed on the relationship between sleep and physical activity (PA) during the school year, when short sleep duration is most common. Furthermore, there is concern that increasing sleep duration may interfere with opportunities for PA, yet this has not been directly tested. This study examined the impact of an at-home experimental sleep extension protocol on PA during the school year among short-sleeping adolescents. PARTICIPANTS/METHODS: Participants included 18 adolescents (67% female, 78% white) who reported regularly sleeping between 5-7 h on school nights. Adolescents completed a five-week, at-home sleep manipulation protocol with an initial baseline week followed in a randomized, counterbalanced order by two experimental conditions, each lasting two weeks. During prescribed habitual sleep (HAB), bedtimes and rise times were set to match the baseline sleep pattern, and during sleep extension (EXT), adolescents were instructed to increase time in bed on school nights by 1.5 h per night relative to baseline. Wrist-mounted actigraphy was employed to monitor sleep and waist-mounted accelerometers were used to measure daytime PA. RESULTS: Adolescents slept for an average duration of 71 min longer on school nights during EXT than during HAB (p < 0.001). During HAB, adolescents spent more time in sedentary behavior (p = 0.002) than during EXT, but there were no cross-condition differences in light activity (p = 0.184) or moderate-to-vigorous PA (p = 0.102). CONCLUSIONS: Extending sleep duration on school nights in short-sleeping adolescents reduces time spent in sedentary behavior, without having a negative impact on health-promoting moderate-to-vigorous PA.

Feasibility and Emotional Impact of Experimentally Extending Sleep in Short-Sleeping Adolescents.

Study Objectives: Published experimental sleep manipulation protocols for adolescents have been limited to the summer, limiting causal conclusions about how short sleep affects them on school nights, when they are most likely to restrict their sleep. This study assesses the feasibility and emotional impact of a school-night sleep manipulation protocol to test the effects of lengthening sleep in habitually short-sleeping adolescents. Methods: High school students aged 14-18 years who habitually slept 5-7 hours on school nights participated in a 5-week experimental sleep manipulation protocol. Participants completed a baseline week followed in randomized counterbalanced order by two experimental conditions lasting 2 weeks each: prescribed habitual sleep (HAB; sleep time set to match baseline) and sleep extension (EXT; 1.5-hour increase in time in bed from HAB). All sleep was obtained at home, monitored with actigraphy. Data on adherence, protocol acceptability, mood and behavior were collected at the end of each condition. Results: Seventy-six adolescents enrolled in the study, with 54 retained through all 5 weeks. Compared to HAB, during EXT, participants averaged an additional 72.6 minutes/night of sleep (p < .001) and had reduced symptoms of sleepiness, anger, vigor, fatigue, and confusion (p < .05). The large majority of parents (98%) and adolescents (100%) said they would "maybe" or "definitely" recommend the study to another family. Conclusions: An experimental, school-night sleep manipulation protocol can be feasibly implemented which directly tests the potential protective effects of lengthening sleep. Many short-sleeping adolescents would benefit emotionally from sleeping longer, supporting public health efforts to promote adolescent sleep on school nights.