FIVE Stages of SleepOn this page: An overview of the Five Stages of Sleep. Points to physical effects of sleep deprivation, natural sleep aids and other snooze tips. We know sleep is critical for our daily survival, and there are plenty of tips on how to sleep better, not to mention the availability of prescription sleep aids or other sleep innovations. But how exactly, do we drift into our sleep world? What happens to our mind and body once we lie down? 
We pass through several stages, before finally becoming dead to the world. Here is what happens to us as we go through the FIVE stages of sleep:Stage 1: This is the light sleep stage. Transition between wakefulness and sleep. Feels good, like a reverie. We can be awakened easily. Eyes move, albeit slowly. Muscle activity slows down. For how long? 5 to 10 minutes. Stage 2: We are now drifting to sleep. Eye movement stops. Body temperature decreases. Heart rate slows down. Slight disturbance can still wake us up, though. And if they do, we may claim we never fell asleep in the first place! We didn't know any better, did we? For how long? About 20 minutes. Brain waves - Theta to Spindle (4-15 Hz) Stage 3: We are getting there. We are at the transition between light sleep and deep state. Extremely slow brain waves. No eye movement. No muscle activity. Increasingly difficult to wake us up now. For how long? Just a few minutes. Brain waves - Theta to Delta (2-4 Hz) Stage 4: We are there. Deep sleep stage. Brain waves the slowest. No eye movement. No muscle activity. Very difficult to wake us up now. For how long? 30 minutes. Brain waves - Delta (0.5-2 Hz) The above four stages are collectively called the Non-REM or NREM stages of sleep. Now onto the most unique of the five stages of sleep. REM Sleep Stage 
Rapid Eye Movement Stage. We don't just jump to this stage from deep sleep stage, though. Instead, we quickly progress backwards - from Stage 4 to 3 to 2 - before settling in the REM stage; it takes about 90 minutes to get here the first time during the night, and successively lesser amount of time, each time after that. And how are we doing here? Brain activity increases. Brain waves are much faster, like we are awake! Breathing quickens. Heart rate increases. Blood pressure rises. So.. are we actually awake? Well, almost - except our muscles are paralyzed! We cannot move. This is called REM paralysis. And yes - we are dreaming! Our brain and body behave like we are awake, but our muscles do not cooperate. So we settle for dreaming! For how long? 10 minutes the first time; progressively increases to an hour, as the night advances to day. Brain waves - Beta (15-30 Hz). We spend about 20% of our nap time in REM stage; and go through 3 to 5 REM stages a night. All the five stages of sleep collectively constitute ONE sleep cycle. A sleep cycle lasts 90 to 110 minutes. And we do this 4 to 5 times a night, to get the recommended 6-8 hours of shut-eye a night! REM Sleep Disorder and Sleep Paralysis
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