iOS: Research shows that light exposure is a major factor in your body's rhythms. Now, mathematicians have built an iPhone app called Entrain that cuts jet lag time and gets your body adjusted to a new time zone faster.
Developed by researchers at the University of Michigan, Entrain is a guide that gives you a schedule that promises to overcome jet lag faster. It doesn't use light sensors or any other automatic input, so it's important that the user submits data — it's not magic!
The science behind the app is that light is the primary diving input to the body's circadian rhythms, so if you feed Entrain your current light input schedule, it can figure out light stimulus that moves your body clock from one phase to another. Detailed maths is available in a paper at PLOS:
These schedules are mathematically proven to adjust you to new time zones as quickly as possible. Light is the primary driving input to the circadian clock, and by recording your lighting history, we can simulate your body's clock and make recommendations for behaviour.
So the first step in using the app is to schedule your current time zone and when you are reaching a new time zone. The next step is the important one: choose the brightest light you can be in during your trip. This is what Entrain uses to figure out a schedule for you that will get your circadian rhythm in line with your new surroundings. From then on, it's a matter of telling the app the light you are currently getting in your scheduling and following the recommendations, which update as you add input.
While it's a great app, it might not be worth the trouble of avoiding jet lag if you're taking a short trip. If you don't have an iPhone, there's an Android version on the way, but for now you will have to rely on other ways to cheat jet lag such as acting by your destination's timezone while flying.
The official website of Entrain linked below has more details about the app and the science.