Evaluation of Infradian and Ultradian Rhythms

• strengths

  • research support for BRAC
  • evolutionary basis of the menstrual cycle
  • practical application for SAD
• research support for BRAC 


  Ericsson et al. (2006)-> studied a group of elite violinists and found that practice sessions were usually limited to a duration of 90 minutes at a time, with practice distributed during the day in these 90-minute segments. it was also indicated that violinists frequently napped to recover from practice, with the very best violinists napping more than the teachers

  Ericsson discovered the same pattern among other musicians, athletes, chess players and writers
• evolutionary basis of the menstrual cycle 


  menstrual synchrony (as demonstrated by McClintock study) is thought to have evolutionary value. for our ancestors it may have been advantageous for females to menstruate together and therefore fall pregnant at the same time. this would mean that new-borns could be cared for collectively within a social group increasing the chances of the offspring's survival
• evolutionary basis of the menstrual cycle COUNTER ARGUMENT 


  researchers have argued that if there were too many females in sync together within a social group, this would produce competition for the highest quality males (and thereby lowering the fitness of any potential offspring). from this point of view no synchrony in menstrual cycles would have been adaptive for survival and for passing on genes to offspring
• practical application for SAD 


  research on infradian rhythms and SAD has allowed the development of effective treatment for SAD. one of the most effective treatments for SAD is phototherapy= a lightbox that stimulates very strong light in the morning and evening. it is thought to reset melatonin levels in people with SAD. this relieves symptoms in up to 60% of sufferers
• practical application for SAD COUNTER ARGUMENT 


  the same study recorded a placebo effect of 30% using a ‘sham negative-ion generator’ (participants were told it was another form of treatment). this brings doubt into the chemical influence of phototherapy
• limitations 


  methodological limitations in menstrual synchronisation studies
• methodological limitations in menstrual synchronisation studies 


  early synchronisation studies have been criticised for not controlling confounding variables. there are many factors that may effect change in a woman’s menstrual cycle, including stress, changes in diet, exercise etc that may have influenced results. this means that any supposed pattern of synchronisation is no more than would have been expected to occur by chance questioning the validity of the results

  the research also typically used small samples of women and relies on ppts. self-reporting the onset of their own cycle