United Airlines has joined other ultra-long-haul operators in the battle against jetlag by partnering with an app designed by top sleep scientists. The US airline has teamed up with an app called Timeshifter that tells users the best time to see and avoid light, sleep and enjoy caffeine to adjust quickly to a new time zone. The app is targeted at passengers flying across three or more time zones and was developed, United says, by top researchers in sleep and circadian neuroscience. These include Dr. Steven Lockley, an associate professor of medicine at Harvard Medical School’s division of sleep medicine. READ: Wine for breakfast on second Qantas Sunrise trial The airline is making a jetlag plan available to all MileagePlus members and giving its top tier Premier 1K members a complimentary annual subscription with unlimited plans. The plan available to MileagePlus members is in addition to a complimentary trial plan from the company, giving the airline's frequent flyers a total of two free flight plans. Users enter their travel schedule information, their normal sleep pattern and individual preferences into the app. It gives them a personalized jet lag alleviation plan that includes when they should prioritize exposure to bright light and when to avoid it as well as a personal sleep and napping schedule. There is also a plan to optimize caffeine intake for alertness and sleep as well as a schedule for taking melatonin where travelers choose to do so. "We want to do everything we can to help improve the experience of traveling across time zones, whether it's a business trip to Tel Aviv or a vacation to Tahiti, our customers should arrive feeling fresh and ready to hit the ground running," said MileagePlus president Luc Bondar. "Timeshifter takes all the guesswork out of avoiding jet lag and instead uses science and algorithms to design a customized, step-by-step trip across time zones. “I was a believer the first time I used the app and I think our customers will love it too." United flies some of the longest routes in the world, including the two longest flights operated by a U.S. carrier with non-stop service between Houston and Sydney and between San Francisco and Singapore.