Infradian Rhythms

Question 1

what are infradian rhythms?

Answer 1

frequency of less than 24 hours in one cycle

Question 2

give 2 examples of infradian rhythms

Answer 2

1. female menstrual cycle = 28 days (therefore less than one cycle in 24 hours)
2. seasonal affective disorder (SAD) = seasonal pattern

Question 3

outline the female menstrual cycle

Answer 3

• rising levels oestrogen cause ovulation
• prostrogen helps womb lining to thicken - readying body for pregnancy
• if pregnancy does not coocur - egg absorbed and womb lining leaves the body (menstrual flow)

Question 4

how did Stern & McClinktock carry out this study?

Answer 4

• took pheromones at different stages of women with irregular periods cycles, via cotton pads under armpit
• rubbed on lip of the other participants

Question 5

what did Stern and McClintock (1998) find in their study?

Answer 5

• 68% women experienced changes to their cycle which brought them closer with the odour donor’s
• that exogenous zeitgebers may synchronise menstraul cycles (infradian rhythms)

Question 6

what type of cycle is a SAD infradian rhythm called?

Answer 6

circannual

Question 7

how may SAD be caused by melatonin?

Answer 7

• lack light during winter means secretion (pineal gland and mealtonin) goes on for longer
• which has a knock on affect on production of serotonin.

Question 8

A03 what is one strength of research into SAD?

Answer 8

practical application

Question 9

A03) what is the practical application of SAD?

Answer 9

the effective treatment phototherapy - lightbox that is thought to reset melatonin levels

Question 10

A03) who’s study discovered that this treatment relieved symptons in 60% of sufferers?

Answer 10

Eastman et al. 1998

Question 11

A03) what is an limitation of Eastman’s (1998) study into phototherpay and what does this suggest?

Answer 11

• same study recorded a placebo effect of 30%
• this cast doubts on the value of phototherapy

Question 13

A03) what is a limitation of synchronisation studies?and what does this suggest?

Answer 13

• there are many confounding variables (diet, stress) which may change a women’s menstrual cycle
• suggest aspects of synchroiastion studies may lack validity.