If you’ve ever been to Paris, you know how beautiful the cobblestone streets are, how decadent the food is, and also what it’s like to ride to the top of the Eiffel Tower with a pounding headache and the overwhelming desire to ignore all the magic and romance, go back to the hotel room, and just sleep.
At its worst, jet lag will ruin vacations, sabotage business meetings, and generally make life miserable until your body finally adjusts. You can chug NyQuil by the thimbleful and pull down your sleep mask, but there’s really nothing more you can do about it. A team of researchers at the University of Michigan and Yale are trying to change that—or at least make it better. Daniel Forger, a professor of mathematics and computational medicine at Michigan, along with grad student Olivia Walch and Yale Ph.D. candidate Kirill Serkh, have developed Entrain, an app that uses your body’s natural circadian rhythms to help you figure out when to wake up and when to go sleep in your new time zone so that you get back on schedule as quickly as possible.
The basic philosophy isn’t that revolutionary—you probably already knew that bright outside light will help you stay awake longer and darkness will help you sleep—but it will tell you exactly when to make the switch according to your personal travel itinerary. This is exactly what bleary-eyed travelers have been waiting for: Entrain is now among the Top 20 most popular travel apps on iTunes (AAPL), ahead of JetBlue (JBLU), Orbitz (OWW), and Skype (MSFT).
To figure out the best sleep schedules for travelers, the researchers studied the raw data of more than 1,000 participants in earlier sleep studies and realized that some ways of resetting the body’s clock were more efficient than others. “The app tells you when to turn the lights off at night and when to turn them back on,” he says. Pick the type of light you’re likely to encounter most on your trip—indoor light is less effective than outdoor—and Entrain will adjust to accommodate those limitations.
Interestingly, one of Entrain’s key concepts flies in the face of conventional jet-lag wisdom. “A lot of people think it’s harder to travel east than west, but according to our schedules it’s actually easier. It’s just that when people travel east, they do the wrong things at the wrong time,” Forger says.
For a trip from New York to Moscow, for example, Entrain would have you wake up at around noon in Moscow (4 a.m. New York time) on the first day, then move everything back and hour and 15 minutes for another three days until you’re finally waking up at 8 a.m. in Moscow, like a normal person. Of course, you’ve probably flown to Moscow overnight and don’t have the luxury of sleeping until noon—which means you’re going to have to endure an entire day of exhaustion until you get rest. Travel west to Hawaii, however, and you’ll probably land in the afternoon or evening, with only a few extra hours to suffer through before you can get to bed. Then your only problem will be trying to make sure you don’t wake up in the middle of Hawaii’s night. Unfortunately for the Hawaii tourist, it’s easier to stay awake than it is to force yourself asleep.
Forger and his colleagues are giving away the Entrain app for free, with the request that users send their anonymous travel and jet-lag data back to the University of Michigan, so he can tweak the models. “We want to know, is jet lag different for men vs. women? Does it matter what time of the year it is? These are things we’re currently trying to find out.”