Sleep improvements on days with later school starts persist after 1 year in a flexible start\xa0system

Anna M. Biller,Carmen Molenda,Till Roenneberg,Eva C. Winnebeck,Giulia Zerbini

doi:10.1038/s41598-022-06209-4

Abstract

Early school times fundamentally clash with the late sleep of teenagers. This mismatch results in chronic sleep deprivation posing acute and long-term health risks and impairing students' learning. Despite immediate short-term benefits for sleep, the long-term effects of later starts remain unresolved. In a pre-post design over 1 year, we studied a unique flexible school start system, in which 10–12th grade students chose daily between an 8:00 or 8:50AM-start. Missed study time (8:00–8:50) was compensated for during gap periods or after classes. Based on 2 waves (6–9 weeks of sleep diary each), we found that students maintained their ~ 1-h-sleep gain on later days, longitudinally (n = 28) and cross-sectionally (n = 79). This gain was independent of chronotype and frequency of later starts but attenuated for boys after 1 year. Students showed persistently better sleep quality and reduced alarm-driven waking and reported psychological benefits (n = 93) like improved motivation, concentration, and study quality on later days. Nonetheless, students chose later starts only infrequently (median 2 days/week), precluding detectable sleep extensions in the flexible system overall. Reasons for not choosing late starts were the need to make up lost study time, preference for extra study time and transport issues. Whether flexible systems constitute an appealing alternative to fixed delays given possible circadian and psychological advantages warrants further investigation.

Highlights

School times fundamentally clash with the late sleep of teenagers
Teenagers around the world are chronically sleep deprived because their late sleep timing often clashes with early school starts forcing them to get up long before their sleep has come to a natural end
School starts are a major determinant of this pattern, thereby impacting students’ daily lives and their future trajectories

Summary

Introduction

School times fundamentally clash with the late sleep of teenagers This mismatch results in chronic sleep deprivation posing acute and long-term health risks and impairing students’ learning. Based on 2 waves (6–9 weeks of sleep diary each), we found that students maintained their ~ 1-h-sleep gain on later days, longitudinally (n = 28) and cross-sectionally (n = 79). This gain was independent of chronotype and frequency of later starts but attenuated for boys after 1 year. Teenagers around the world are chronically sleep deprived because their late sleep timing often clashes with early school starts forcing them to get up long before their sleep has come to a natural end. One notable exception is a recent study by Widome and colleagues who followed students over 2 years and found persisting extended sleep durations (measured with 1 week of actimetry) in students from schools who delayed bell times compared to students in schools which did not c hange[42]

Methods

Results

Conclusion