Infradian Rhythms- Menstrual cycle

Question 1

What is an infradian rhythm?

Answer 1

A biological rhythm with a cycle longer than 24 hours, such as weekly, monthly, or yearly cycles.

Question 2

What is a circannual rhythm?

Answer 2

A type of infradian rhythm that occurs on a yearly basis, such as Seasonal Affective Disorder (SAD).

Question 3

What are weekly rhythms in humans?

Answer 3

Patterns in behaviour across the week, such as higher testosterone and sexual activity at weekends. Some studies also show weekly variations in blood pressure and heart rate (Halberg et al., 2002).

Question 4

Why is evidence for weekly rhythms considered weak?

Answer 4

Much of the behavioural variation may be socially constructed rather than biologically driven.

Question 5

What is the menstrual cycle and how long does it typically last?

Answer 5

A monthly infradian rhythm, typically lasting 28 days, involving hormonal changes that regulate ovulation and menstruation.

Question 6

What hormones regulate the menstrual cycle?

Answer 6

Oestrogen (causes egg release and ovulation) and progesterone (prepares womb lining for pregnancy).

Question 7

What was the aim of Stern and McClintock’s (1998) study?

Answer 7

To investigate whether female menstrual cycles synchronise due to pheromones.

Question 8

What were Stern and McClintock’s procedures?

Answer 8

Pheromones from 9 women’s armpits were collected and applied to the upper lips of 20 others; cycle changes were then tracked.

Question 9

What did Stern and McClintock (1998) find?

Answer 9

68% of women experienced cycle changes that brought them closer to the odour donor’s cycle—suggesting synchrony via pheromones.