Sleep Stages

-there are 5 identified stages of sleep
-it takes about 90-100 minutes to pass through the 5 stages
-the brains waves will change according to the sleep stage you are in
-the first four stages are known as NREM sleep...
-the fifth stage is called REM sleep

Stage 1: 
-kind of awake and kind of asleep
-only lasts a few minutes, and you usually experience it once a night
-eyes begin to roll slightly
-your brain produces theta waves (high amplitude, low frequency (slow))

Stage 2: this follows stage 1 sleep and is the "baseline" of sleep
-this stage is part of the 90 minute cycle and occupied approximately 45-60% of sleep
-more theta waves that get progressively slower
-begin to show sleep spindles...short bursts of rapid brain waves

Stage 3 and 4
-slow wave sleep
-you produce delta waves
-if awoken you will be very groggy
-vital for restoring body's growth hormones and good overall health
-May last 15-30 minutes
-it is called "slow wave" sleep because brain activity slows down dramatically from the "theta" rhythm of stage 2 to a much slower rhythm called "delta" and the height or amplitude of the waves increase dramatically
-contrary to popular belief, it is delta sleep that is the "deepest" stage of sleep (not REM) and the most restorative
-it is delta sleep that a sleep-deprived person's brain craved the first and foremost
-in children, delta sleep can occupy up to 40% of all sleep time and this is what makes children unawakeable or "dead asleep" during most of the night

REM sleep
-rapid eye movement
-often called paradoxical sleep
-brain is very active
-dreams usually occur in REM
-body is essentially paralyzed

Stage 5: REM Sleep
-composed 20-25% of a normal nights sleep
-breathing, heart rate and brain wave activity quicken
-vivid dreams can occur
-from REM, you go back to stage 2