Entrain works by providing you with an altered “lighting” schedule, based on where you’re travelling to and when. For each hour, it’ll tell you what sort of lighting you should be in when you sleep. If you make a mistake, you can mark on the schedule the lighting conditions you were in and whether or not your were awake.
At first glace, it’s not immediately obvious how Entrain works. Thankfully, the app’s website features a comprehensive FAQ, which does a good job of explaining the underlying concepts.
An Android version is apparently on the way, with the iOS build serving as a testing ground. If you can’t wait, the research paper the app is based on is freely available.