1. Increased time in bed through advancing bedtime in adolescents was associated with increased sleep duration.
2. Total sleep time increased by 41.5 minutes for every additional hour spent in bed.
Evidence Rating Level: 2 (Good)
Study Rundown: Decreases in sleep duration throughout adolescence are linked to negative academic and mental health outcomes. This prospective cohort study sought to identify the impact of an intervention consisting of advancing adolescent bedtimes to increase time in bed (TIB), on total sleep time and quality of sleep. One cohort of 77 participants between 9.9 years and 14.0 years of age was enrolled and followed annually for 3 years, and another cohort of 73 participants between the ages of 15.0 and 20.6 years was followed for 1 year. Several sleep measurements were recorded for 3 weeks per year, with each week consisting of either 7, 8.5, or 10 hours in bed. TIB was increased by advancing bedtime. Electroencephalogram (EEG) and sleep duration monitors were used, and sleep staging, TST, sleep onset latency (SL), and wake after sleep onset (WASO) measurements were recorded. Sleep duration increased linearly with TIB, with a 41.5-minute increase in TST per additional hour in bed. The results of this study provide evidence for the advancement of bedtime as a method to increase total sleep time in adolescents. One limitation is that it was conducted in a highly controlled manner, which is not representative of the day-to-day life of an adolescent. Nevertheless, the study provides compelling evidence that increasing TIB through bedtime advancement in adolescents results in increased sleep duration, and further studies should investigate this strategy in a real-world setting.
Click to read the study in Pediatrics
Relevant Reading: Differential and interacting effects of age and sleep restriction on daytime sleepiness and vigilance in adolescence: a longitudinal study
In-Depth [prospective cohort]: Two cohorts, one comprised of 77 participants between ages 9.9 years and 14.0 years, and another cohort comprised of 73 participants between ages 15.0-20.6 years were included in the study. EEG and sleep monitoring measurements were conducted across 4 days within 3 separate weeks per year, with each week comprising either 7, 8.5 or 10 hours of TIB per day. TIB was modified by advancing bedtime. In the condition of a 7-hour TIB, the mean TST was 402.8 minutes with a standard error (SE) of 1.6 minutes. In the 8.5 hour TIB condition, the mean TST was 470.6 (2.1) minutes, and 527.5 (3.0) in the 10-hour TIB condition. These results show a 41.5 (0.7) minute increase in TST per additional hour in bed. No sex differences were observed. As age increased, TST decreased by about 1.5 minutes per year, with REM duration increasing by 3 minutes per year and NREM duration decreasing by about 4.3 minutes per year. In the oldest age quartile, more than 36% of participants took over 30 minutes to fall asleep during the 10-hour TIB condition, while in the youngest age quartile, less than 20% of participants took over 30 minutes to fall asleep.
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