ultradian rhythms

Question 1

ultradian rhythm

Answer 1

a biological rhythm with a frequency of more than one cycle in 24 hours

Question 2

an example of an ultradian rhythm

Answer 2

the sleep cycle

Question 3

what does the sleep cycle contain

Answer 3

five distinct stages of sleep that span approximately 90 minutes each

Question 4

how can the sleep cycle be measured

Answer 4

by eegs monitoring different levels of brain activity

Question 5

stage 1 and 2

Answer 5

• light sleep where a person can easily be woken
• brain wave patterns start to slow down `

Question 6

stages 3 and 4

Answer 6

• deep sleep or slow wave sleep where a person is difficult to wake
• brain waves are even slower than stage 1 and 2

Question 7

stage 5

Answer 7

• rem
• the body is paralysed yet brain activity speeds up significantly resembling an awake brain
• highly correlated with dreaming

Question 8

whats the key study for ultradian rhythms

Answer 8

dement and kleitman

Question 9

what was the aim

Answer 9

To investigate brain activity change throughout night-time sleep.

Question 10

what was the method

Answer 10

Seven adult males and two females were asked to report to the laboratory at bedtime where they
were connected to an EEG which took measurements throughout their time asleep. Participants
were asked not to drink caffeinated drinks for the day before their sleep was investigated.

Question 11

what were the results

Answer 11

They found that all participants had periods of REM every night. They also found high incidences of
dream recall when participants were awakened during REM periods of sleep and if awakened
during other stages very few reported dreaming.

Question 12

what was the conclusion

Answer 12

The study suggests that sleep follows a typical pattern throughout the night.

Question 13

small sample size

Answer 13

Dement & Kleitman only had a small sample of 9 people of whom only 2 were female. This
means that the population validity of this sample is limited.
E As such, their conclusion that sleep follows a typical pattern throughout the night may be
invalid since their sample may be unrepresentative of a wider population and hence may not
apply to the sleep cycle of others.
E However, there is no evidence that this is, in fact the case. As such, it is reasonable to argue
that the small sample size is not sufficient reason to discount the findings or conclusions of this
research.
E

Question 14

eeg is an objective measure

Answer 14

A strength of Dement & Kleitman’s research is that EEGs provide highly empirical data.
E EEGs provide objective evidence to show that sleep follows a typical pattern throughout the
night.
E This is a strength because these findings provide verifiable evidence for ultradian rhythms.

Question 15

sleep stages are biologically determined

Answer 15

There is evidence to suggest that sleep patterns may be biologically determined.
E For example, Tucker et al found large differences between individuals’ sleep patterns, which
were consistent over 11 nights in a controlled sleep lab. Individuals also responded very
differently to 36-hour periods of sleep deprivation.
E This suggests that sleep patterns may be at least partially determined by genes.