Afternoon School Start Times Are Associated with a Lack of Both Social Jetlag and Sleep Deprivation in Adolescents

Morning-shift students had a 1 h 45 min shorter sleep duration than those attending afternoon shifts.

• Both morning and afternoon shift students had similar sleep onset times on school days.
• Morning-shift students experienced an earlier sleep offset compared to their afternoon peers.
• Only morning-shift students took afternoon naps, which were insufficient to alleviate sleep deprivation.
• On weekends, morning-shift students woke up later and had longer sleep durations, leading to social jetlag.
• There was no difference in the time spent on leisure activities or electronic media between shifts during school days.

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