Tuesday, January 10, 2023

Sleep architecture

Sleep:
    EEG shows, sleep is a dynamic behavior, not a passive activity.
    Neuroendocrinological structures and chemicals responsible for sleep regulation are:
  • Sleep promoting neurons in anterior hypothalamus acts through cerebral cortex with neurotransmitters
  • Sleep promoting hormone Melatonin produced in the pineal gland.
Sleep stages:
1. NREM sleep:
    No rapid eye movement.
    Restorative sleep, bodily recovery and growth
    Boosts immune system
    As you age, less NREM sleep
    N3 for insightful thinking and creativity.
2. REM sleep:
    Rapid eye movement.
    Essential to cognitive functions like memory, learning, creativity & vivid dreams.
    Deprived of REM sleep shortens life span.
    REM declines with growing age.

Sleep cycle:
    A hypnogram based on brain waves shows:
    1. 4-6 sleep cycles in a night.
    2. Each cycle last 90 minutes on average.
    3. Each cycle with 4 sleep stages;

Stage 1  NREM  N1       wake-sleep transition state                           1-5 mins          
Stage 2  NREM  N2       most of NREM sleep occurs in this stage   10-60 mins      
Stage 3  NREM  N3       slow wave-, delta-, deep sleep                     20-40 mins     
Stage 4   REM   REM    active sleep                                                    10-60 mins     

               N1, N2, N3 amounts 75%, while REM amounts 25% of all sleep.

Some other terms used, less often:
  1. Core sleep: Slow wave sleep, mainly N2 and Deep sleep N3.
  2. Optional sleep: rest of the sleep is grouped as Optional.



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