Infradian

• Stern & McClintock 1998 et al. 


  
  

  • female hormones influence synchronisation of menstrual cycles
  • 29 Ps with irregular period, 9 pheromone samples, 20 Ps rubbed on upper lip
  • 68% had cycle changes therefore menstrual cycle influenced by zeitgebers
• Seasonal Affective Disorder

  
  

  • depressive disorder with seasonal pattern triggered during winter with less daylight hours; circannual (yearly and circadian - darkness disrupts sleep-wake cycle)
• what causes SAD

  melatonin hormone
• why/how does melatonin cause SAD

  pineal gland secretes melatonin at night until light - takes longer in winter because it's darker; reduces production of serotonin - linked to depressive symptoms
• AO3 limitation - evolutionary basis of menstrual cycle


  
  

  • ancestors menstruate together
  • advantage so they could collectively raise baby to increase chances of offspring's survival; CA - Schank 2004 = would've created competition for highest quality males
  • therefore avoidance of synchrony most adaptive strategy instead, suggesting natural selection
• AO3 limitation - methodology

  
  

  • 29 women experiencing different stress levels, diet, exercise - relies on self-reporting
  • external factors as confounding variables which creates opportunity for inaccuracy therefore menstrual synchrony could've been by chance or individual differences mentioned.
• AO3 strength - practical application of SAD

  
  

  • Eastman 1998 = phototherapy relieves symptoms in 60% sufferers
  • light stimulation resets melatonin levels therefore effective treatment