The effects of sleep extension and sleep hygiene advice on sleep and depressive symptoms in adolescents: a randomized controlled trial

OBJECTIVE: Sleep problems are common and persistent during adolescence and can have negative effects on adolescents' mood. To date, studies that investigate the effects of sleep extension on adolescents' sleep and depressive symptoms are still lacking. This study aims to investigate the effects of gradual sleep extension combined with sleep hygiene advice in adolescents with chronic sleep reduction on objectively measured sleep, self-reported sleep problems and depressive symptoms. METHODS: Fifty-five adolescents with chronic sleep reduction (mean age: 15.44 years; 85.5% females) were included in the study. Participants were randomly assigned to either a sleep extension group (gradual sleep extension by advancing bedtimes in the evening and receiving sleep hygiene advice) or to a control group (no instruction). Sleep was measured with actigraphy during three weeks, the first week was the baseline week, and the last two weeks were the experimental weeks during which sleep was extended. Other outcome variables were self-reported sleep problems (daytime sleepiness, symptoms of insomnia and circadian rhythm sleep disorder) and depressive symptoms, which were assessed before and after the experimental manipulation. RESULTS: During the third week of the experiment, adolescents in the sleep extension group had earlier bedtimes, earlier sleep onsets, spent more time in bed and slept longer than adolescents in the control group. Their chronic sleep reduction, insomnia symptoms and depressive symptoms diminished significantly. In addition, there was a trend of improved circadian rhythm sleep disorder symptoms and sleep quality. CONCLUSION: Gradual sleep extension combined with sleep hygiene advice seems to have beneficial effects on sleep, self-reported sleep problems and depressive symptoms of adolescents with chronic sleep reduction. Although we cannot distinguish between the effects of sleep extension and sleep hygiene advice, the results suggest that advancing bedtimes can extend sleep and improve depressive symptoms.