ultradian rhythm Flashcards
how often does an ultradian rhythm occur?
one cycle is more often than 24 hours
(with a cycle of sleep being approximately 90 minutes)
draw the stages of the sleep cycle
how were stages of sleep discovered?
through EEG brain scans, wave patterns in the brain change as we sleep
what brain waves are found at each of the 4 stages of sleep?
stage 1- beta wave (awake, mental activity)
stage 2- alpha wave (awake/ resting)
stage 3- theta wave (sleeping)
stage 4- delta wave (deep sleep)
what are sleep spindles and where do they occur?
they are the troughs in the alpha waves
when does dreaming occur?
during the return of alpha waves
draw the different frequencies of beta, alpha, theta and delta waves
what are stages 1 and 2 of the sleep cycle?
they are a light sleep where the person may be easily woken. at the beginning of sleep, the brainwave patterns start to become slower and more rhythmic (alpha waves), becoming even slower as sleep becomes deeper (theta waves)
what are stages 3 and 4 of the sleep cycle?
these involve delta waves which are slower and have a greater amplitude than earlier wave patterns. this deep is a sleep (or slow wave sleep) and it is difficult to rouse someone at this point
what is stage 5 of the sleep cycle?
the REM sleep. the body is paralysed yet brain activity speeds up significantly in a manner that resembles the conscious brain. REM stands for rapid eye moment to denote the fast, jerky activity of the eyes under the eyelids at this point. research has suggested that REM activity during sleep is highly correlated with the experience of dreaming.
what is REM sometimes referred to as?
ambiguous sleep
why might sleep walking occur?
it may occur when you are in deep sleep but the body isn’t paralysed
•melatonin makes us paralysed to keep us safe and repair our brains
description of sleep stage 1
•1-7 minutes
•heart beat slows
•breathing slows
•eye movement slows
•muscles relax and occasionally twitch
description of sleep stage 2
•light
•10-25 minutes
•heart rate/ breathing rate slows more
•muscles relax more
•body temperature drops
•eye movements stop
•brain wave activity slows
description of sleep stage 3
•deep sleep
•20-40 minutes
•heartbeat/ breathing slows to lowest levels
•muscles stay relaxed
•brain waves slow more
deep sleep stage 4
•REM
•20-40 minutes
•eyes move rapidly from side to side
•breathing speeds up/ can become irregular
•heart rate increases
•blood pressure increases
evaluation- evidence supports the idea of distinct stages in sleep
•a study by Dement and Kleitman monitored the sleep patterns of mine adult participants in a sleep lab
•brainwave activity was recorded on an EEG and the researchers controlled for the effects of caffeine and alcohol
•REM activity during sleep was highly correlated with the experience of dreaming, brain activity varied according to how vivid dreams were, and participants woken during dreaming reported very accurate recalls of their dreams
•replications of this investigation have noted similar findings, though the small size of the original sample has been criticised
•nevertheless, this study suggests that REM (dream) sleep is an important component of the ultradian sleep cycle
evaluation- limitations
•there is evidence we don’t have a full 8 hours of sleep but 2 sections of sleep with a woken period in the middle around 2am
-an example of individual differences (eg if you’re pregnant you’ll sleep differently)
•it’s possible that sleep patterns and relationships between eye movements and dreaming varies from person to person
•conclusions drawn from the study can’t be generalised
strength: improved understanding
•an understanding of ultradian rhythms improves research into age- related changes in sleep
•research shows that slow sleep waves tend to reduce with age, which is why older people may struggle to sleep more and have reduced alertness in the daytime
•this suggests knowledge of ultradian rhythms have practical value
limitation: individual differences
•there is a significant variation in ultradian rhythms between people
•tucker found large differences between participants in terms of each sleep stage
•she determined that these differences are likely to be biologically determined
•this makes it difficult to describe ‘normal sleep’ in any meaningful way
