Wakefulness and sleep

Sleep occurs in two steps. First one is Non-Rapid Eye Movement (NREM) and another is Rapid Eye Movement (REM).

NREM

This also occurs in 4 stages

  • Stage 1 lasts about 7 min and can be interrupted by any small noise.
  • Stage 2 lasts for 15-25 min and may interrupt by intense noise.
  • Stage 3 and 4 lasts for about 25-40 min. These are deep sleep or slow wave sleep.

REM

  • This become longer progressively
  • Dreaming occurs in this phase
  • Nervous system is activated
  • Low muscle tone

 

Stage 0 is wakefulness stage. It is also called fully alert stage.

 

 

 

 

Mechanism of sleeping and wakefulness

  • Regulated by circadian system

This regulates wakefulness .this decrease during sleeping time.

 This is due to:

  • Change in adrenaline concentration
  1. Increase in adrenaline concentration: wakeful
  2. Decrease in adrenaline concentration : sleep

 

  • Change in temperature
  1. Increase in body temperature: wakeful
  2. Decrease in body temperature: sleep
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