Infradian Rhythms AO3

• +Evolutionary basis - for our distant ancestors it may've been advantageous for women to menstruate together and become pregnant at the same time. In a social group, it would allow babies who had lost their mothers to have access to breast milk, thereby improving their chances of survival. This suggests that synchronisation is an adaptive strategy.
• -Many things can change a woman's menstrual cycle and act as confounding variables - stress, diet. Any supposed pattern may occur by chance. This may be why others such as Trevathan haven't replicated Stern annd McClintock’s original findings. This suggests that menstrual synchrony studies are flawed.
• + Light therapy reduces the debilitating effects of SAD -excessive sleepiness - in around 80%. of people (Sanassi). Its safer than using antidepressants. However, Rohan recorded a relapse rate of 46% over successive winters compared to 27% in a comparison group receiving CBT. This suggests that light therapy may be an effective

  short term treatment but additional treatments may be required if benefits are to be maintained.