🟢 Biopsychology - Infradian & Ultradian Rhythms

Question 1

What is an infradian rhythm

Answer 1

A rhythm that last longer than 24 hours and can be weekly, monthly or annually

Question 2

3 examples of infradian rhythms

Answer 2

• female menstrual cycle
• seasonal affective disorder
• hibernation (in animals)

Question 3

Menstrual cycle

Answer 3

• monthly changes of hormone levels which regulate ovulation
• the cycle refers to the time between the first day of a women’s period, when the womb lining is shed to the day before her next period
• 28 days approx
• rising levels of the hormone oestrogen causes the ovary to develop an egg and release it (ovulation)
• after ovulation, the hormone progesterone helps the womb lining to grow thicker, readying the body for pregnancy
• if pregnancy doesn’t occur the egg is absorbed into the body and the womb lining comes away and leaves the body

Question 4

Study on menstrual cycle

Answer 4

• although the menstrual cycle is an endogenous system, evidence suggests that it may be influence by exogenous factors such as the cycles of other women

Study by Kathleen Stern and Martha McClintock (1998) demonstrated how menstrual cycles may synchronise as a result of the influence of female pheromones

Question 6

Stern and McClintock (1998)

Answer 6

• 29 women with a history or irregular periods
• samples of pheromones gathered from 9 of the women at different stages of their menstrual cycles via a coffin pad placed in their armpit
• pads worn atleast 8 hours
• pads then treated with alcohol and frozen and then to be rubbed on the upper lip of the other participants
• day 1= pads from start of menstrual cycle applied to all 20 women, and on day 2 all given a pad form the second day of the cycle and so on
• found 68% of women experienced changes to their cycle which brought them closer and closer to their ‘odour donor’

Question 7

What is seasonal affective disorder (SAD)

Answer 7

Infradian rhythm related to the seasons (yearly cycle)