ultradian rhythms

Question 1

how many stages of sleep are there?

Answer 1

5 stages

Question 2

describe the features of stages 1&2 of the sleep cycle.

Answer 2

• light sleep, where the person may easily be woken.
• at beginning of sleep, brainwave patterns start to become slower and more rhythmic (alpha and theta waves).

Question 3

describe the features of stages 3&4 of the sleep cycle.

Answer 3

• delta waves, which are slower still and have a greater amplitude than earlier wave patterns.
• aka deep sleep or slow wave sleep.
• difficult to wake someone at this point.

Question 4

describe the features of stage 5 of the sleep cycle.

Answer 4

• REM sleep where the body is paralyzed yet brain activity speeds up significantly so much that it resembles the awake brain.

REM = rapid eye movement + is associated with dreaming.

Question 5

describe the study of Dement + Kleitman (1957).

Answer 5

• monitored the sleep patterns of nine adult participants in a sleep lab.
• investigated the relationship between eye movements in REM and non-REM sleep.

Question 6

describe the procedure of Dement + Kleitman (1957).

Answer 6

– monitored 9 adult participants for between 6-17 nights.
- their brain activity was recorded on an EEG.
- they all consumed no caffeine or alcohol as a control.

Question 7

what were the conclusions of Dement + Kleitman (1957)?

Answer 7

• more dreams recalled from REM than NREM sleep.
• p’s could accurately estimate dream duration.
• p’s eye movements were strongly related to dream content.
• REM activity during sleep was highly correlated with the experience of dreaming.
• brain activity varied according to how vivid dreams were,
• p’s woken during dreaming reported very accurate recall of their dreams.

Question 8

what were 3 methodological issues of Dement + Kleitman’s study?

Answer 8

low ecological validity - because participants are in an extreme artificial environment (e.g. sleeping wired up to an EEG, being restricted from caffeine and alcohol).

demand characteristics - Dream recalls may not have been entirely true due to people feeling annoyed, wanted to get back to sleep quickly, being embarrassed.

lack of generalizability - Only 7 participants from the USA.

Question 9

why is evidence for individual differences in the sleep cycle a limitation of Dement and Kleitman’s study?

Answer 9

limitation of the sleep cycle: individual differences.

Tucker et al (2007) found large differences between participants in terms of the duration of each sleep stage – esp in stages 3&4.

These are likely to be biologically determined.

This makes it hard to study sleep using a nomothetic approach.

Question 10

what age related changes have been noted with sleep?

Answer 10

strength = understanding age-related changes in sleep.

Slow wave sleep reduces with age. Growth hormone is being produced during slow wave sleep, so this becomes deficient in older people. Van Cauter et al (2000) suggests the reduced sleep may explain impairments in old age.

Slow wave sleep can be improved using relaxation and medication.

This suggests that knowledge of ultradian rhythms has practical value that can impact clinical treatment.