If you're going to eat a balanced breakfast, go running, and save the world by 10 a.m., you really should wake up earlier. But don't try to change overnight. "Go to bed five minutes earlier each night and wake up five minutes earlier every day" until you reach your goal, says Timothy Monk, Ph.D., a professor of psychiatry at the University of Pittsburgh Medical School who is leading a NASA study to find the best way of shifting astronauts' sleep schedules. If you're changing time zones, "mitigate jet lag before you travel," says Margaret Rappaport, a sleep-training specialist. If you're flying from San Francisco (Pacific time) to Boston (Eastern time), "sleep on Central time in the days before the flight," she says. Once in Beantown, immediately adopt the local schedule. For a drastic change in routine — say, a switch to the graveyard shift — try to trick nature. "When you want to be awake, keep rooms bright," Monk says. "And minimize daylight exposure before sleep by wearing dark glasses outside and dimming lights inside."