Stages of sleep

• Sleep has a cylical pattern every 90 minutes
• before sleep metabolic, heart rates and temperature drops, alpha wave on EEG

Stages of Sleep

• Slow wave sleep - stage 1, alpha waves replaced by slower desychronised waves
• stage 2 - EEG becomes sychronised with larger waves, interrupted my 'sleep spindles'
• stage 3- large slow delta waves boby rates drop further
• stage 4- delta waves only shown, with low rates and a high arousal threshold.

• REM (Rapid eye movement) sleep occurs 30 minutes after stage 4
• after this stage 2 starts followed by deeper stages of 3 and 4.
• REM lasts longer in cycles towards the morning

Characterists of REM;

• increase in body rates
• relaxation and paralysis of sketal muscles