Stages of Sleep

what did dement and kleitman say?

• sleep is an ultradian bio-rhythm

• has five stages which last 90 mins together

• the cycle is repeated five to six times each night

• first four stages are NREM and the last stage is REM

how long is stage one?

15 mins

what happens in stage one?

• brain waves slow from rhythmic alpha waves. they form slow irregular theta waves until a pattern is formed

• heart rate slows, muscles relax

• hypnoggic state and myaclonic jerk occur

what happens at a hypnoggic state?

hallucinations: the internal landscape of your mind mixes with the real world

what is a myalonic jerk?

• where you feel like your falling, your body jerks and you wake up

• the disconnection of your environment and your balance

what is a spindle?

burst of alpha activity during theta waves

what is a k-complex?

burst of delta activity during theta waves

what are alpha waves like?

small, rapid changes in polarity

what are beta waves like?

irregular, small changes in polarity

what are theta waves like?

larger, irregular, slower changes in polarity

what are delta waves like?

the largest, slow changes in polarity

what are stages 2 and 3 like (together)?

• a bridge between stages four and five

• transitional

• get shorter through the night

what is stage two like? (NREM)

• more spindles than k-complexes

• theta waves continue to slow

• interspersed with sleep spindles

• brain registers stimulus outside without waking

• heart rate and body temperature fall

how long does stage two occur for?

20 mins

how long does stage three occur for?

15 mins

what happens at stage 3? (NREM)

• more k-complexes than spindles

• theta waves slow into delta waves

• heart rate and body temp keep falling

how long is stage four?

30-40 mins

what happens at stage 4? (NREM)

• growth hormone is secreted

• metabolic rate is slowest

• very hard to wake up (except in extreme situations)

• sleepwalking and talking is most likely to occur

how long does stage five last?

10-15 mins

what happens at stage five? (REM)

• very rapid

• brainwaves rapidly speed up, become irregular and complex

• brain oxygen and glucose increase

• paradoxical sleep

draw the process of the stages of sleep

stage 1 -> stage 2 -> stage 3 -> stage 4 -> stage 5 -> stage 2 or awake (cycle continues from stage 2)