ultradian rhythm

Question 1

how often does an ultradian rhythm occur?

Answer 1

one cycle is more often than 24 hours
(with a cycle of sleep being approximately 90 minutes)

Question 2

draw the stages of the sleep cycle

Question 3

how were stages of sleep discovered?

Answer 3

through EEG brain scans, wave patterns in the brain change as we sleep

Question 4

what brain waves are found at each of the 4 stages of sleep?

Answer 4

stage 1- beta wave (awake, mental activity)
stage 2- alpha wave (awake/ resting)
stage 3- theta wave (sleeping)
stage 4- delta wave (deep sleep)

Question 5

what are sleep spindles and where do they occur?

Answer 5

they are the troughs in the alpha waves

Question 6

when does dreaming occur?

Answer 6

during the return of alpha waves

Question 7

draw the different frequencies of beta, alpha, theta and delta waves

Question 8

what are stages 1 and 2 of the sleep cycle?

Answer 8

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)

Question 9

what are stages 3 and 4 of the sleep cycle?

Answer 9

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

Question 10

what is stage 5 of the sleep cycle?

Answer 10

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.

Question 11

what is REM sometimes referred to as?

Answer 11

ambiguous sleep

Question 12

why might sleep walking occur?

Answer 12

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

Question 13

description of sleep stage 1

Answer 13

•1-7 minutes
•heart beat slows
•breathing slows
•eye movement slows
•muscles relax and occasionally twitch

Question 14

description of sleep stage 2

Answer 14

•light
•10-25 minutes
•heart rate/ breathing rate slows more
•muscles relax more
•body temperature drops
•eye movements stop
•brain wave activity slows

Question 15

description of sleep stage 3

Answer 15

•deep sleep
•20-40 minutes
•heartbeat/ breathing slows to lowest levels
•muscles stay relaxed
•brain waves slow more

Question 16

deep sleep stage 4

Answer 16

•REM
•20-40 minutes
•eyes move rapidly from side to side
•breathing speeds up/ can become irregular
•heart rate increases
•blood pressure increases

Question 17

evaluation- evidence supports the idea of distinct stages in sleep

Answer 17

•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

Question 18

evaluation- limitations

Answer 18

•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

Question 19

strength: improved understanding

Answer 19

•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

Question 20

limitation: individual differences

Answer 20

•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