Sleep during travel balances individual sleep needs.

Travel is expected to have a deleterious effect on sleep, but an epidemiological-scale understanding of sleep changes associated with travel has been limited by a lack of large-scale data. Our global dataset of ~20,000 individuals and 3.17 million nights (~218,000 travel nights), while focused mainly on short, non-time-zone-crossing trips, reveals that travel has a balancing effect on sleep. Underslept individuals typically sleep more during travel than when at home, while individuals who average more than 7.5 hours of sleep at home typically sleep less when travelling. The difference in travel sleep quantity depends linearly on home sleep quantity and decreases as median sleep duration increases. On average, travel wake time advances to later hours on weekdays but earlier hours on weekends. Our study emphasizes the potential for consumer-grade wearable device data to explore how environment and behaviour affect sleep.