You are wrong if you think sleep is a passive. In fact, sleep is a very active state.
Two Main Types of Sleep
|Non-Rapid Eye Movement (NREM) Sleep||It occurs during the first 90 minutes.
It restores the physical body.
It releases growth hormones.
It stimulates the immune system to defend against infections.
|Rapid Eye Movement (REM) Sleep||It occurs after REM sleep.
It restores the brain.
It captures memories which allow learning to process.
Stages of Sleep
|Stage 1 (light sleep)||
|Stage 3 (deep sleep)||
|Stage 4 (deep sleep)||
REM(Rapid Eye Movement)
- It usually occurs about 70 to 90 minutes after we fall asleep
- Breathing becomes more rapid, irregular and shallow, eyes jerk rapidly and limb muscles become temporarily paralyzed.
- The brain waves are increased to levels usually seen when a person is awake.
- Dreams are most likely to occur.
- Most people experience REM sleep three to five intervals a night.
- Infants spend almost 50% of their time in REM sleep.
- Adults spend nearly half of sleep time in stage 2, 20% in REM, 10% in stage 1, 10% in stage 3, and 10% in stage 4.
- Older adults spend progressively less time in REM sleep.
The complete cycle from stage 1 through to REM can last roughly 90 to 110 minutes, and these cycles can occur multiple times throughout the average sleep. During an eight-hour rest period, a person will cycle through all the stages of sleep four or five times on average.