Infradian and ultradian rhythms

Question 1

What is Infradian rhythm? e.g

Answer 1

occurs over 24hrs e.g menstruation cycle and sad ( seasonal affective disorder)

Question 2

menstrual cycle
support for menstrual cycle

Answer 2

The typical cycle takes about 28 days to complete.

Mclintock ( 1998) demonstrated how women menstrual cycle synchronise

Mclintock involved 29 women with a history of irregular periods.
Samples of pheromones were gathered from 9 women at different stages of cycle.

Cotton pads were placed under their armpit.
The pads were worn for 8 hrs to ensure the pheromones were picked up.

The pads were treated with alcohol and frozen and rubbed on the upper lip of other participants.

He found that 68% of women experienced changes to their cycle which brought them closer to cycle of their “odour donor”

Question 3

Seasonal affective disorder (SAD)

Answer 3

It is a depressive disorder which has a seasonal pattern of onset.

Sad is particular type of Infradian rhythm called circannual rhythm

However it can be classed as circadian rhythm as may be caused by disruption of sleep wake cycle.

Question 4

What is ultradian rhythm? + e.g

Answer 4

occurs less than 24hrs e.g stages of sleep cycle.

Question 5

what are stages of sleep?

Answer 5

Stage 1 and 2 - known as “sleep escalator” is a light sleep where a person may be easily woken. At the beginning of sleep, brain wave patterns start to become slower and more rhythmic.

Stage 3-4 - involves delta waves which are slower. This is slow wave sleep.

Stage 5 rem ( rapid eye movement) sleep = the body is paralysed yet brain activity speeds up significantly in a manner that resembles the awake brain.

Question 6

evaluation

Answer 6

Mclintock study is thought to have evolutionary value. for ancestors it would have been advantageous for females to menstruate together and therefore fall pregnant around the same time. this means Newborns would be cared for collectively within a social group increasing chance of survival.

• there are many factors which affect a women menstrual cycle this could be to stress, diet and exercise and this could count as confounding variables. this means any synchronisation that occurs for e.g Mclintock study would be because of chance.

Individual differences = tucker et al found large differences between the duration of sleep for different people.