Sleep is your body’s time to revamp itself. While you’re getting your z’s, your body balances your hormones and increases the rejuvenating human growth hormone. It’ll help you to understand the mechanics of sleep, along with what’s going on at each sleep stage.Sleep LatencyThe time it takes for you to fall asleep once you’re in bed.Stages 1 and 2 – Light SleepDrowsiness as your brain is just getting into sleep. In stage 2, your brain waves start to slow down noticeable, resting those parts you use while awake.Stages 3 and 4 – Deeper SleepThese stages are both restorative. Both REM sleep and sleep stages 3 and 4 are homeostatically driven—that is, if you are selectively deprived of one of these, it rebounds once you are allowed to sleep. This means that both stages 3 and 4 are essential in the sleep process and its functions. You get less of this type of sleep as you age because of frequent awakenings.REM – The Deepest SleepREM is short for rapid eye movement. Your eyes are moving fast, but the rest of your body is paralyzed. It’s the stage where some sleep-related disorders take place, like sleepwalking.WATCH VIDEO: How Sleep Cycles WorkYour Sleep CyclesEach of these cycles lasts about 90 minutes, and you go through four to six of them a night. But the important part is that you have to get to REM sleep to feel rested. People who have sleep problems often don’t make it to REM sleep because it takes up to 60 minutes to get to it. If you’re waking up frequently before you make it to REM, then you’re never getting that restorative, healthy sleep.As you awaken, complex changes occur in your body and mind. Your melatonin levels have peaked, the stress hormone cortisol is on the rise, your body temperature has bottomed out and your psyche is immersed in your dreams.Increased levels of melatonin associated with deep sleep promote immune system activity, protect you from viruses, and have remarkable anticancer properties.Deep sleep also increases human growth hormone naturally, so the levels oscillate as they are supposed to, and you start to feel like a puppy. Growth hormone also plays a critical role in fostering optimal body weight.QUIZ: Do You Have Good Sleeping Habits?