Weekly alternation of morning and afternoon school start times: implications for sleep and daytime functioning of adolescents

Adolescents experienced an average bedtime delay of 36 minutes and wake-up time delay of 121 minutes on an afternoon school schedule.

• All age groups reported delayed sleep patterns when attending school on an afternoon schedule compared to a morning schedule.
• Average sleep durations varied from 9.80 hours for 11-year-olds to 8.39 hours for 18-year-olds.
• Delays in wake-up times on the afternoon schedule were linked to increased substance use and lower academic performance.
• Later bedtimes were associated with poorer grades and less frequent depressive moods.
• Longer sleep durations on the afternoon schedule correlated with reduced daytime sleepiness, lower depressive moods, and decreased substance use.

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