menstrual cycle -infradian rhythm

Question 1

What is the difference between an ultradian, circadian, and infradian rhythm?

Answer 1

Circadian- biological process that repeats approx once every 24 hours
Infradian- biological process that repeats LESS requently than once every 24 hours e.g. weeks/months
Ultradian- biological process that repeats MORE frequently than once every 24 hours e.g. minutes/hours

Question 2

What is another infradiam rhythm apart from the menstrual cycle?

Answer 2

Seasonal Affective Disorder (SAD)- emotional mood lowers in the winter and improves in summer, due to lack of bright sunlight

Question 3

How long is the menstrual cycle?
What are 3 biological aspects of this cycle

Answer 3

28 day cycle, 6 day period of fertility
The releasing of the egg (ovulation), thickening of the womb lining, losing the womb lining during menstration

Question 4

What are the biological aspects of the menstrual cycle regulated by?
What do these act as?

Answer 4

Hormones: oestrogen (pre ovulation) and progesterone (post ovulation)
Hormones act as EP, keeping the biological processes to time, acting as an internal body clocks for the cycle

Question 5

What did McClintock study?
What did results how?

Answer 5

135 women who lived in the same dorms at uni
Recorded their period duration
Results showed women appeared to synchronise their cycles with their friendship groups

Question 6

How did Stern add to McClintock’s research?
What did they find?

Answer 6

Investigated if synchronisation was due to women sharing pheromones (aura)
20 women were given pads to wipe on their top lip each day, pads had been taken from the armpits of 9 donor women at varying stages of their cycles
Found that the women would either shorten or extend their cycles to match the donor, depending on when in the donor’s cycle the pad had been collected

Question 7

What does McClintock’s research suggest?

Answer 7

Synchonisation was due to the presence of pheromones, acting as an EZ, external cue for the timing of the infradian rhythm

Question 8

Strength and weakness of infradian rhythm

Answer 8

+ there have been some replications of McClintock with positive results
- however there have been a number showing no synchronisation e.g. Trevatham:
Showed cohabiting (optimal conditions for synchronisation) lesbian couples did not synchronise,

Question 9

2 additional weaknesses of infradian rhythm

Answer 9

Pheromones as chemical messengers are not accepted widely as a process that happens in humans
Menstrual cycles can vary in length, women appear to sychronise just due to their variability in their cycles -this isn’t taken into consideration