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What is social jet lag?

Last updated: October 15, 2026

Social jet lag is the gap between when your body clock wants you to sleep and the schedule work or school imposes, measured as the shift in your sleep timing between workdays and days off. Researchers coined the term because it resembles flying across time zones every weekend.

How it is measured

Researchers calculate the difference in midpoint of sleep between work nights and free nights. A 2-hour difference = 2 hours of social jet lag.

Health impact

In a large study, social jet lag was linked to a higher body mass index, beyond the effect of sleep duration (Roenneberg et al., 2012). Other research links it to poorer wellbeing and more smoking and alcohol use (Wittmann et al., 2006). These are associations, not proof of cause.

Solution

Stable wake time 7 days a week. If you cannot match it to your chronotype perfectly, get morning bright light to help your body adapt.

Sources

1. Wittmann et al., Chronobiology International, 2006. Social jetlag: misalignment of biological and social time
2. Roenneberg et al., Current Biology, 2012. Social jetlag and obesity