Ultradian Rhythms - NREM/REM Sleep Flashcards
Explain what NREM and REM is in ultradian rhythms
A typical adult will have 4-5 sleep cycles that last approximately 90 minutes each night. These cycles begin with NREM (slow wave sleep) and are followed by Rapid Eye Movement sleep.
Discuss research studies in Ultradian Rhythms: Sleep laboratory
Dement et al - the participant is wired up to a polysomnograph. i.e. Electro Encephalograph (EEG - measures brain activity), Electro Oculograph (EOG - measures eye movement), Electro Myograph (EMG - measure muscle tension) and sensors to detect pluse body temp, blood pressures etc. the participant then goes to sleep in the lab, and all these functions are recorded. usually the participant spends several nights in the sleep lab. In the Dement study, 9 participants were studied for up to 61 nights in a laboratory. The mean time of a NREM/REM cycle was 92 minutes.
Evaluation:
Polysomnographs have been indispensable in studying sleep. they are used in controlled studies, giving objective unbiased findings which are reliable, having been replicated many times, and so are highly scientific. However, sleeping in the lab, wired up in this way is somewhat artificial, and sleep patterns may differ under normal conditions.
Discuss research studies in Ultradian Rhythms: Animal Studies
Jouvet - lesioned the raphe nucleus in cats and found that this resulted in sleeplessness. Lesioning the locus coeruleus resulted in loss of REM sleep. These appear to be the endogenous factors involved in the REM/NREM ultradian rhythm.
Evaluation:
These studies have provided invaluable evidence to suggest that the raphe nuclei and locus coeruleus are the endogenous factors which control the NREM/REM cycle. Carefully controlled scientific procedures were used which have been replicated by other researchers.
However, many critics of animal studies argue that it is not possible to generalise from animals to humans. this represents the behavioural discontinuity view i.e. that we are qualitatively different to animals and it is clear that cats’ sleeping patterns (nocturnal) differ significantly from humans. indeed it has been suggested that animal sleep research would be best carried out on birds as unlike most mammals, birds have a diurnal sleep pattern just as humans do. Therefore studies of bird sleep may be more easily generalisable to humans, than studies of cats or hamsters. However, this research does focus on the most primitive brain structures, and although our highly evolved cortex can modify their effects, we are still unlikely to be able to override these primitive mechanisms.
