infradian and ultradian

Question 1

Infradian rhythm

Answer 1

A type of biological rhythm with a frequency of less than one cycle in 24 hours, such as menstruation and seasonal affective disorder

Question 2

Ultradian rhythm

Answer 2

A type of biological rhythm with a frequency of more than one cycle in 24 hours, such as the stages of sleep (the sleep cycle)

Question 3

Menstrual cycle

Answer 3

Oestrogen regulates ovulation, progesterone readies body for pregnancy (endogenous factors)

Question 4

Synchronising the menstrual cycle

Answer 4

Menstrual cycles synchronised through pheromones, exogenous factor (stern and McClintock)

Question 5

Stern and McClintock

Answer 5

Menstrual cycles may synchronise as a result of the influence of pheromones
- 29 women with a history of irregular periods
- Pheromones gathered from 9 at different stage of cycle
- Rubbed on upper lip of other participants
- On day one, pads from the start of the menstrual cycle were applied to all 20 women, on day two they were given a pad from the second day of the cycle and so on
- 68% of women experienced changes to their cycle - brought them close to the cycle of their odour donor

Question 6

Ultradian rhythm example

Answer 6

stages of sleep

Question 7

Stages of sleep

Answer 7

5 stages - 90 min cycle
- 1 and 2 - alpha waves and sleep spindles
- 3 and 4 - deep sleep, delta waves
- REM sleep, theta waves

Question 8

Seasonal affective disorder

Answer 8

Form of depression triggered in the winter months and regulated by melatonin, circandian rhythm

Question 9

Evolutionary basis - infra

Answer 9

• Strength - explained by natural selection
• Synchronisation may have an adaptive function, leads to shared care for babies - if have same period, get pregnant at the same time - access to breast milk

Question 10

Methodological limitations - infra

Answer 10

• Methodological shortcomings
• Stress, changes in diet, exercise
• Many confounding variables not controlled, so synchronisation may occur by chance (Trevathan et al)

Question 11

Real-world application - infra

Answer 11

• Light therapy - 80% effective for SAD - (Sanassi)
• Relapse rate is 46% (Rohan et al) - 27% for CBT

Question 12

Improved understanding - ultra

Answer 12

• Improved understanding. Of age-related changed in sleep
• SWS reduces with age, explains issues in old age e.g. - reduced alertness (van Cauter et al)
• Practical value

Question 13

Individual differences - ultra

Answer 13

• Significant variations between people
• Differences found in duration of each sleep stage, particularly stages 3 and 4 - Tucker et al
• Difficult to describe normal sleep in any meaningful way

Question 14

The sleep lab - ultra

Answer 14

• Lab studies of sleep control extraneous variables - eg noise - but may not represent ordinary sleep patterns due to complicated machinery attached