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Later high school start times associated with longer actigraphic sleep duration

Page history last edited by Dolores Skowronek 3 years, 7 months ago

Nahmod, N. G., Lee, S., Master, L., Chang, A. M., Hale, L., & Buxton, O. M. (2018). Later high school start times associated with longer actigraphic sleep duration in adolescents. Sleep. Advance online publication.  https://doi.org/10.1093/sleep/zsy212

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Study Objectives

High school start times (SSTs) directly impact adolescents' sleep timing and duration. This study investigated the associations between SSTs and actigraphically-measured 24-hour sleep duration, sleep onset, sleep offset and sleep quality.



This study included 383 adolescents (Mage=15.5, SDage=0.6 years) participating in the age 15 wave of the Fragile Families & Child Wellbeing Study, a national birth cohort study sampling from 20 large U.S. cities. Multilevel models used daily observations (N=1,116 school days, Mdays =2.9, SDdays=1.4 per adolescent) of sleep and SSTs from concordant daily diary and actigraphy.



A diverse range of SSTs were included in our analyses (MSST=8:08, SDSST=39 minutes, RangeSST=6:00-11:05), and are presented in the following categories for ease of interpretation: before 7:30, 7:30-7:59, 8:00-8:29, and 8:30 or later. Adolescents starting school at 8:30 or later exhibited significantly longer actigraphically-assessed 24-hour sleep duration (by 21-34 minutes, p<.05) and later sleep offset (by 32-64 minutes, p<.001) when compared with the adolescents grouped by earlier SSTs. SSTs were also analyzed continuously for comparison with existing literature, and results indicated that every one-hour delay in SST was significantly associated with 21 minutes longer 24-hour sleep duration (p<.001), 16 minutes later sleep onset (p<.01), and 39 minutes later sleep offset (p<.001). All models controlled for covariates including socioeconomic status.



These findings support pediatric and public health expert recommendations for SSTs after 8:30 a.m. In our diverse national urban sample, adolescents with SSTs at 8:30 or later, compared with adolescents with earlier SSTs, had significantly longer actigraphy-measured sleep.



School start times, actigraphy, adolescence, sleep duration, sleep timing, education policy, pediatric sleep, sleep quality


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