Book your flight, pack your bags, and set your jet lag app: three key steps for a smart start to your journey. Entrain takes into account your habitual hours of sleep, and suggests an action plan that you can even start some time before your trip. It recommends when to go to sleep day by day, as well as when you should seek natural or artificial light. For smartwatch users who love their metrics, Entrain takes it one step further by integrating data relative to your physical activity, as long as you have an app or device that can monitor steps and heart rate. The icing on the cake is a short questionnaire on your emotional state and a brief test that records your reaction times. Developed at the University of Michigan, Entrain is available free of charge for iOS and Android.