The first REM cycle of the night usually lasts about 10 minutes, and it occurs 90 minutes after you fall asleep. As the night goes on, each REM stage will get longer, with the last one potentially reaching an hour in length. People average about four to five REM cycles a night. Interestingly, we spend less time in REM sleep the older we get. While babies can spend up to 50% of their sleep in this stage, adults average about 20 to 25% in REM3. According to Girardin Jean-Louis, Ph.D., professor of population health and psychiatry at New York University, it is ideal to wake up after a full sleep cycle—though it’s hard to train your body to do that. “If one comes to the end of a full night’s sleep, one wakes up naturally—that’s the ideal way to wake up,” he says. “It is difficult to train oneself to wake up during any stage of sleep (since one is no longer aware of one’s surroundings), unless conditioned with an alarm.” Rebecca Robbins, Ph.D., sleep researcher and co-author of Sleep for Success!, adds, “The most important thing to do before drawing attention to your wake-up time is to ensure you are spending enough time to get the sleep your brain and body need.” Regular exercise and a balanced diet that’s low in caffeine and alcohol can help promote good sleep hygiene. But even if you’re doing all the right things, sometimes stress and shifting schedules make it difficult to fall asleep at the same time every night. In that case, you might want to consider adding a sleep-promoting supplement to your routine (might we suggest mbg’s sleep support+?).*