Dormitory Effect

The menstrual synchrony theory of psychologist Martha McClintock proposes that living together would tend to synchronize the menstrual cycles of women. Although no scientific evidence has been found to support this theory, the (supposed) phenomenon was dubbed "the McClintock effect" or the "Wellesley effect". McClintock's paper in Nature proposed that social interaction could affect the menstrual cycle, but her study had methodological flaws and other published studies failed to find synchrony.