When I was a young and inexperienced personal trainer, I used to think diet, supplementation, and a solid exercise program were all you needed to get and stay in shape. I overlooked the importance of sleep.



With experience, I've come to realize that sleep is often the deciding factor in whether or not someone succeeds.



You'll spend more of your life sleeping than doing any other activity, so you have to get it right if you want to maintain your health.



Here's everything you need to know to master the art of sleep.





How Sleep Works



You aren't conscious of it, but your body is hard at work while you sleep, physically and mentally rebuilding and repairing itself.



Like the foreman on a job site, who directs and organizes electricians, carpenters, and plumbers in a methodical process, so they don't interferes with one another's work, your body divides sleep into different segments, so it can effectively address one part of the body, and then move onto another.



Throughout the night, your brain cycles through three stages of sleep: light, deep, and rapid eye movement (REM) sleep.



Each cycle lasts about 90 minutes, so with normal sleep, you go through four to six cycles per night. Your sleep quality is determined by the amount of time you’re in deep and REM sleep, not just by the time you spend with your eyes shut.



Most adults sleep in one, large block of time, which is also called a "monophasic" sleep pattern.



Children and the elderly do best with a “biphasic” sleep pattern, meaning they need a nap in the middle of the day to complement their nighttime slumber.



How Much Sleep Do You Need?



GroupAgesIdeal SleepOlder Adult65+7-8Adult18-647-9Teenager14-178-10School Age6-139-11Preschool3-510-13Toddler1-211-14Infant4-11 months12-15Newborn0-3 months14-17



Light Sleep



During light sleep, you’re semi-conscious. You’re aware of your environment, but only respond to something unexpected, such as the creaking of a door or your spouse whispering seductively in your ear.



You have enough awareness to make sense of what’s happening, but are asleep enough that you're often unmotivated to move unless you sense a threat, or you're a newlywed.



When you're under a heavy amount of stress, you can spend most of your night in this phase, and miss out on the benefits of the next two phases.



Deep Sleep



Deep sleep supports growth and repair of your body.



Provided you remain in light sleep without interruption, 10-30 minutes later, you enter deep sleep.



Deep sleep supports your body’s physical recovery, whereas REM sleep supports your brain and mind.



A burglar would have the best chance of stealing something in this stage because you don't hear anything, and your muscles are temporarily paralyzed.



You even lose your ability to regulate your body temperature, which is why it’s so important to sleep in a cool bedroom whenever possible.



During deep sleep, growth hormone rises, supporting tissue repair, fat metabolism, and a number of other positive health effects.



Though dreams sometimes occur during deep sleep, it is rare.



In a typical night, you enter deep sleep three to five times.



Rapid-Eye Movement (REM) Sleep



REM sleep supports growth and repair of your brain.