Infradian Rhythms

Question 1

What is an ‘Infradian Rhythm’?

Answer 1

• A type of biological rhythm with a frequency of less than one cycle in 24 hours, such as Mensuration or SAD.

Question 2

Briefly describe the ‘Mensuration Cycle’.

Answer 2

• Cycles can vary between 23 and 36 days but the most common is 28 days.
• During each cycle, rising levels of oestrogen cause the ovary to develop an egg and release it this is called - Ovulation and is accompanied by an oestrogen peak at 16-32 hours.
• After ovulation, progesterone levels then increase which eps the uterus lining to grow thicker, readying the body for pregnancy.
• If pregnancy doe snot occur then the uterus lining sheds and the egg leaves the body. - this is the Menstrual flow.
• Although the menstrual cycle is an Endogenous system, evidence suggests that it may be influences by Exogenous factors such as cycles of other women.

Question 3

What research suggest that the Menstrual Cycle is impacted by Exogenous Factors?

Answer 3

• 29 women with irregular periods were used.
• Samples of Pheromones were taken from 9 of the women at different stages of their menstrual cycle via a cotton pad placed in their armpit which were worn for 8 hours.
• The pads were treated with alcohol and frozen to then be rubbed on the upper lip of there other participants.
• On day one, pads from the start of the menstrual cycle were applied and on day two they were given a pad from the second day of the cycle and so on.
• 68% of women experienced changes to their cycle which brought them closer to the cycle of their ‘odour donor’.