Infradian Rhythm

• Infradian Rhythm-

  • over 24 hours
• Infradium Rhythms-

  Menstrual cycle-

  • Oestrogen releases the egg
  • Proestrogen thickens the lining of the uterus
  • 28 day cycle
• Infradian Rhythm-

  Stern and Clintock- 1998

  • Investigated the synchronising of the menstrual cycle
  • 29 women with irregular periods
  • Each in different stages of their cycle
  • Pheromones taken from 9 women via a cotton pad in their armpits for 8 hours, daily
  • Treated with alcohol and freezing to be sterile
  • Rubbed on the upper lip of the other 20 women, each day of their cycle
  • 68% of women had changed to be more alike their ‘odour donor’
• Infradian Rhythm-

  Seasonal affective disorder (SAD)

  • Depressive disorder with a seasonal pattern
  • Symptoms- depression, persistent low mood, lack of activity and interest in life
  • Symptoms often triggered by winter due to the reduced daylight
  • Circannual rhythm due to it being annual, and circadian due to its effect on the sleep wake cycle
  • Slower inhibitation of melatonin due to the darker morning, meaning there is less serotonin produced.
• Infradian Rhythm-

  S- Explained in natural selection- pregnant at the same time, so offspring shall always be cared for if their mother dies.

  W- Confounding variables- stress, diet, exercise