Infradian

• A cycle in biological or psychological activity that occurs less than once every 24 hours.


  Infradian rhythm
• Menstrual cycle - occurs once, on average, every 28 days

  Seasonal Affective Disorder (SAD) - a form of seasonal depression. 


  Examples of infradian rhythms
• • Many IRs are clearly controlled endogenously. For example the menstrual cycle is governed by the pituitary gland, releasing hormones to control ovulation.
  • However it is through that exogenous zeitgebers influence IRs. Menstrual cycle - influenced by pheromones, SAD influenced by light.
• Russell et al (1980)

  • Took samples of sweat from women in one group and applied it to the top lip of women from another group.
  • The groups were kept separate, but the second groups menstrual cycle still became synchronised with the women from group 1.
  • Supports the idea that pheromones act as an EZ because the study was able to isolate pheromones as the sole factor that would cause the synchronisation.

  AO3 of Infradian Rhythms
• • A strength of research into bodily rhythms is that it has many practical applications.
  • This suggests ongoing research into bodily rhythms can benefit real peoples lives.