This document summarizes the stages of sleep. There are two main types: non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. NREM sleep has four stages: Stage 1 is light sleep; Stage 2 is slightly deeper sleep; Stage 3 and 4 make up delta sleep and are the deepest stages; REM sleep involves dreaming and rapid eye movements. The stages progress in depth from Stage 1 to Stage 4 of NREM sleep, then into REM sleep, cycling throughout the night.

1. Mrs Priyanka P Sarda
ASSISTANT PROFESSOR
MODERN COLLEGE OF PHARMACY
Yamunanagar Nigdi PUNE

3.  There are two main types of sleep:
 Non-rapid eye movement (NREM), also known as
quiet sleep
 Rapid eye movement (REM), also known as active
sleep or paradoxical sleep

4. Stages of NREM Sleep
Stage 0
From lying down to falling asleep
Stage 1
 Stage 1 is the beginning of the sleep cycle and is a
relatively light stage of sleep.
 Stage 1 can be considered a transition period between
wakefulness and sleep.
 This period of sleep lasts only a brief time (around five to
10 minutes).
 If you awaken someone during this stage, they might
report that they were not really asleep.
 eyes movement slowed down and body muscle relaxes

5. Stage 2
 Stage 2 is the second stage of sleep and lasts for
approximately 20 minutes.
 During stage 2 sleep:
 You become less aware of your surroundings.
 Body temperature drops.
 Breathing and heart rate become more regular.
 More decrease in eye movement
 Person may arousable
 According to the American Sleep Foundation, people
spend approximately 50% of their total sleep in this
stage.5

6. Stage 3
 During stage 3 sleep:
 Muscles relax.
 Blood pressure and breathing rate drop.
 Deeper sleep occurs with minimum eye movement
 Not easily arousable

7. Stage 4
 The stage 3and 4 is also sometimes referred to as delta
sleep.
 Deepest level of sleep
 Metabolic rate is lowest
 No eye movement
 Growth hormone secretion is highest
 Muscles are fully relax
 If awakened Disorientation for 1 to 2 min

8. REM Sleep (rapid eye movement).
 During REM sleep:
 The brain becomes more active.
 The body becomes relaxed and immobilized.
 Dreams occur.
 Eyes move rapidly.
 Enhanced heart rate breathing and brain activity
 Relaxation of voluntary muscle
 Dream can be recalled
 Most dreaming occurs during this stage. The American
Sleep Foundation suggests that people spend
approximately 20% of their total sleep in this stage.