Biological rhythms: ultradian rhythms Flashcards
ultradian rhythm definition
biological rhythm with a frequency of more than one cycle in 24 hours (takes less than one day) such as the stages of sleep
what is one of the most insensitively researched ultradian rhythms
sleep cycle
what is the sleep cycle
5 distinct stages of sleep that altogether last for 90 mins and continues throughout the night
how is each stage of the sleep cycle characterised
different level of brainwave activity
how is brainwave activity monitored
using and EEG
what types of brainwaves is in stage 1
alpha waves
what types of brainwaves is in stage 3
delta waves
what types of brainwaves is in stage 2
alpha waves but occasional change in pattern called sleep spindles
what types of brainwaves is in stage 4
delta waves
what types of brainwaves is in stage 5
theta waves
stage 1 and 2 of sleep cycle
-light sleep where person can be easily woken
-alpha waves which have a high frequency and short amplitude
-during stage 2 these alpha waves continue but there are occasional random changes in pattern called sleep spindles
stage 3 and 4 of sleep cycle
-deep sleep or slow wave sleep (SWS)
-brain waves are delta waves which have a lower frequency and higher amplitude
-difficult to wake someone at this point
stage 5 of sleep cycle
-body is paralysed but brain activity closely resembles that of an awake brain
-theta waves are produced and the eyes occasionally move around which is called rapid eye movement (REM)
-dreams are most often experienced during REM sleep, but can also occur in deep sleep
strength of ultradian rhythms - improved understanding
-research into ultradian rhythms has improved understanding of age-related changes in sleep
-sleep scientist have observed that the SWS reduces with age. growth hormone is mostly produced during the SWS (slow wave sleep) and therefore this is reduced in older people. Van Cauter et al 2000, resulting sleep deficit may explain various issues in old age, such as reduced alertness. in order to increase SWS, relaxation and medication may be used –> suggests knowledge of ultradian rhythms has practical value
limitation of ultradian rhythms - individual differences
-significant variation between people
-Tucker at al 2007 found larger differenced between participants in terms of duration of each sleep stage, particularly stages 3 and 4. Tucker et al suggest that these differences are likely to be biologically determined –> makes it difficult to describe ‘normal sleep’ in any meaningful way