A biologicalrhythm that lasts less than 24 hours, experience more than one cycle a day
example of ultradian rhythm
sleep cycle
how many stages in the sleep cycle?
4 take around 90 minutes to cycle through
go through about 4-6 each night
how is each sleep cycle stage characterised?
by differentlevels of brain waveactivity
what are the stages of the sleep cycle?
stage 1 to 2 - light sleep
stage 3 - deep sleep
stage 2 to 1 - light sleep
REM
what does light sleep involve?
brainwaves slightly slower than the awakestate,graduallyslowermoving from stage 1 to 2
may be easilywoken
what does deep sleep involve?
slow wave sleepcharacterised by slowdelta waves, difficult to wakesomeone
what does REM sleep involve?
rapideye movement, fast jerkyactivity of the eyes. body paralysed yet brainactivityspeeds up
alpha waves
research support
Dement and Kleitman conducted landmarklab experiment with 9 Ps which firstdiscovered the link between REMsleep and dreaming.
confoundingvariables such as caffeine and alcohol were controlled
replications have shown similarfinding
differences in sleep are blamed on external factors
nature vs nurture
Tucker had Pssleep in a lab for 11 days, each time they spent in eachsleepstagevaried even though the environment was keptconstant. therefore individualdifferences are caused by nurture not nature
real world application
suggested that 90 min sleep cycle continuesthroughout the day, go through 90 mins of alertness followed by 20minutes of fatigue