Passengers stretched out on an airport terminal seat at Gatwick, London. Sleeping while waiting for their flight, the two men rest head to head on the bench in the south Terminal.In Pictures Ltd./Corbis via Getty Images The Australian airline Qantas is conducting test flights to find a cure for jet lag on long flights. The airline is testing changes to in-flight menus, lighting, and exercise offerings for passengers. Menus with chili and chocolate help keep people awake, while light exercise helps travelers sleep better. Planning a long-haul flight this summer?