There are many apps that help you with jetlag but Timeshifter is the first jetlag app designed and tailored specifically to the user, showing you when to avoid/seek daylight, take in caffeine, nap and sleep during travel to other time zones. Timeshifter is developed by awarding-winning scientists, including Dr. Steven Lockley of Harvard University (who has studied sleep/wake cycles for 20 years) and Dr. Smith Johnston, NASA's medical director and performance specialist.
Unlike other jetlag apps, Timeshifter is custom tailored to the user's circadian rhythm, the body's 24-hour internal clock. Users input sleep details (when you normally sleep, wake up, etc.), flight details (down to how many stops, exact airports, layover cities, etc.), and their chronotype (whether you're an early bird or night owl, since this affects sleep and alertness patterns and everyone has slightly different circadian rhythms).
Once you travel, you can get advice delivered as notifications during your transition to the new time zone and until you return home. It also offers a detailed graph of what to do and not to do from the morning you depart, and suggestions on how to get a good night's sleep (eye masks, warm bath, for example), as well as what time you should see bright light (light, such as the sun, has the most powerful influence on circadian rhythms, and see light at the right time is an important factor), all within reasonable times in your new time zone.
Timeshifter costs $9.99 per jet lag plan (both one way or round-trip), or $24.00 for an annual subscription.