Infradian rhythms

  • Created by: gemshort
  • Created on: 17-05-18 20:36

Infradian rhythms: a type of biological rhythm with a frequency of less than one cycle in 24 hours, such as the menstrual cycle and seasonal affective disorder

The menstrual cycle

  • Governed by monthly changes in hormone levels (oestrogen and progesterone)
  • Its purpose is to regulate ovulation and prepare for pregnancy
  • When pregnancy does not occur, hormones cause the womb lining to be shed
  • It is approximately a 28-day cycle but can be anywhere between 24-35 days
  • It may also be affected by external factors (pheromones)

Stern and McClintock (1998)

  • Studied 29 women who had irregular periods
  • Samples of pheromones were gathered from 9 of the women at different stages


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