Stages of Sleep
• EEG (electroencephalogram) introduced by Berger in 1929 recorded brain activity and showed …
• Clearly identifiable stages of brain activity during sleep (Dement, Aserinsky & Kleitman (1950’s).
• Brain activity looks different when someone is awake or asleep.
• When they are asleep 2 distinct types can be seen – NREM and REM.
NREM goes through different stages
Two Main Types of Sleep
• Slow-wave sleep (NREM)
• Rapid eye movement (REM) sleep
Up and down the “sleep escalator”
• Most people have 5 cycles of sleep a night that last approximately 90 minutes. Slow-wave sleep (SWS) occurs in only the first two cycles; REM sleep occurs in all of the cycles,…