Millions of Nights’ Worth of Anonymized Sleep Data Show People Actually Enjoy Better Sleep the Further West — or Back in Time — They Travel

GOTHENBURG, Sweden — July 31, 2019 — All jet lag is not created equal, according to new data released today from Sleep Cycle, the world’s first and most popular smart alarm clock app.

The new report from the Sleep Cycle Institute looked at more than 1.5 million nights’ worth of sleep data from people who traveled east (forward in time), west (backward in time) and without traversing any time zones (the control group) to get a quantitative look at how travel interferes with our sleep. 

The most significant finding of the new report is that traveling east (forward in time) is significantly worse for sleep than traveling west (backward in time). In fact, it seems that westbound travelers may enjoy better sleep than usual.

Time, travel and shuteye

Looking at the first five days of travel, not only do people enjoy less severe jet lag when they travel west, but their quantity of sleep, quality of sleep and wake-up mood actually improve. This is true not only compared to eastbound travelers but also to people who travel without moving through any time zones — and the effect is greater the further west they go.

On the other hand, the further east people travel, the poorer their quantity of sleep, quality of sleep and wake-up moods become:


What most travelers seem to have in common, regardless of how much or whether or not they’re traveling through time, is that they sleep fairly well the first night of their trip but see a marked decline in sleep quality on night two. On day five or six, sleep quality peaks, and their sleep returns to normal around day 10. This is seen in time changes as low as three hours but is augmented when traveling further distances.

Observations from the experts

Sleep Cycle asked some of the Sleep Cycle Institute panelists for further commentary about jet lag. Australian sleep expert, neuroscientist and health educator Dr. Chelsie Rohrscheib said jet lag from vacation travel is unlikely to have any lasting negative effects but can be a serious problem for frequent travelers like airline crew members.

Long-term jet lag is serious because it’s essentially the same as being chronically sleep-deprived,” she said. “The bodies of chronically jet-lagged individuals can’t function properly because the brain has a difficult time sending the appropriate signals when it’s not running on its normal internal clock. Long-term jet lag is associated with the same health risks as long-term sleep deprivation, including an increased risk of certain cancers, metabolic issues, heart disease, obesity, and diabetes.”

Natural sleep expert Dr. Catherine Darley added, “Based on sleep physiology, it makes sense that westward travel is easier, as it is easier to lengthen the circadian rhythm. Not only is mood worse, but people can feel an increase in anger and performance problems. It’s important to note that these effects can last for several days and to take that into account when planning. For those people who travel regularly, there are strategies that can decrease the disruption caused by jet lag.”

We want to help the world to better sleep. By using Sleep Cycle to track your sleep and find your perfect wake up window, we believe you’ll be part of that change, for the benefit of better health. Disclaimer. Would you like to contribute to better world sleep? Sharing your sleep data is easy and always anonymous. On your iOS device in your Sleep Cycle app, go to Settings – Advanced at the bottom – Profile – and activate Participate in survey. Follow the same simple steps to opt out, should you at any time change your mind.