infradian rhythms

infradian rhythms

• repeating biological rhythms that last more than 24 hrs such as menstrual cycles (hormones) or SAD. (seasonal affective disorder

Research - pheromones

• McClintock: 29 women with irregular menstrual cycles.

• gathered pheromones from 9 women all in diff stages of cycle - applied to lip of ppt

• Findings: found 68% of women experienced change

• cycle was similar to donor

• due to exogenous zeitgeber (pheromones)

Seasonal affective disorder

• depression linked to certain seasons

• linked to melatonin hormone - secreted in night until dawn

• winter: lack of light, longer secretion of melatonin

• SAD affects serotonin production in brain - linked to depression

strength - real world application

• practical application as Sanassi found light therapy improved symptoms of 80% of patients.

• Preferred over antidepressants however, Kelly Rohan rt al found it has 46% experience relapse

• Short time effectiveness but should be combined with CBT for a long term effect

strength - evolutionary explanation to menstrual cycle

• stern and McClintock found the syncing of menstrual cycles has an evolutionary advantage

• synchronisation means if women get pregnant at same time, child who lost their mother can still be breastfed and nurses

• menstrual synchrony increases infant survival rates

limitation - methodological issues in synchronisation studies

• presence of cofounding variables

• changes in diet, stress, exercise can all affect womens menstrual cycle - makes it difficult to establish cause and effect

• lack internal validity as unsure if pheromones caused changes or another uncontrolled variable