Karen is a freelance health and science reporter in the Baltimore area. Her work has appeared in the Baltimore Sun, on AARP.org, and in numerous magazines for physicians and allied health professionals.
With travel-industry experts predicting a busy U.S. travel season, we’re again considering how vacations may uproot our routines. Although travel is associated with having trouble sleeping because of the effects of jet lag, sleeping in a hotel, a new study suggests that may not always be true.
Researchers say that traveling may have a balancing effect on sleep for people who are short on sleep at home and those who oversleep.
Sleep changes when we travel may depend on how much sleep we typically get at home, researchers found. Individuals who usually sleep five or fewer hours at home are more likely to sleep longer when away. Those who usually sleep nine or more hours at home tend to sleep less when they are away.
Most adults need between seven and nine hours of sleep each night for health and well-being.
To understand travel’s impact on sleep, researchers at the Technical University of Denmark collected sleep data from wearable health monitors of almost 20,000 people from 121 countries. Spanning 2015 to 2019, this data provided insight on 3.17 million nights of sleep, including 218,000 evenings people spent away from home.
Researchers discovered that people who typically sleep less than 6.2 hours on weekdays at home went to bed earlier on weeknights when traveling. In comparison, those who sleep 7.5 hours or less at home went to bed earlier on weekend travel nights. Participants tended to wake up later on weekdays but earlier on weekends.
The researchers also looked at how long people slept when they traveled on weekdays compared to weekends. Although sleep duration changed for both timeframes, travelers generally gained more sleep on weekdays than weekends.
Travel’s effect on sleep was greater among individuals whose weekday sleep differed considerably from their weekend sleep, a situation called “social jet lag.”
People with high social jet lag usually get only four to five hours of sleep on weeknights but sleep nine to 10 hours on weekends, according to the study. These individuals gained 45 minutes of sleep on average when spending weeknights away from home but lost 32 minutes of sleep on average on weekends.
Why does this social jet lag occur? People may sleep less on weeknights because they need to wake up early for work or school. But they may not go to sleep early enough to get the full amount of sleep they need, the study authors say. When traveling for vacation, early wake-up times may be less common, “therefore, there is more opportunity to gain sleep,” researchers say. They also acknowledge that the “opposite effect is expected for weekends, when there is more opportunity to lose sleep.”
Individuals in the study were more likely to lose sleep if their travel took them across one or more time zones. People were more likely to lose sleep when traveling east than west. This had a bigger impact on weekdays than weekends.
Most of the trips recorded in the study were relatively short-distance. About 81% were less than 620 miles, and 85% of the trips did not cross any time zones. Researchers also say they didn’t know if participants were traveling to new or familiar destinations or if their trips were for business or leisure.
With COVID-19 pandemic travel restrictions loosening or ending in many areas, more people may be planning trips in the coming months. It may be a good idea to consider travel tips for sleep as part of trip-planning.
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