Lunar effect purported lunar-lunacy connection, and at least 20 published studies on the purported lunar-birthrate connection. This has allowed several extensive literature reviews and meta-analyses to be produced, which have found no correlation between the lunar cycle and human biology or behavior. Examples of the belief have been found in ancient Assyrian/Babylonian writing. Claims of a lunar connection have appeared in the following contexts: It is widely believed that the Moon has a relationship with fertility due to the corresponding human menstrual cycle, which averages 28 days. However, no connection between lunar rhythms and menstrual onset has been conclusively shown to exist,
Menstrual synchrony synchrony. Setchella, Kendala, and Tyniec investigated whether menstrual synchrony occurred in a semi-free-ranging population of mandrills of 10-group years. They reported that mandrills do not synchronize their menstrual cycles and concluded that cycle synchrony does not occur in non-human primates. Oestrus synchrony has been reported of female lions living under natural conditions in the wild. Menstrual synchrony Menstrual synchrony, also called the McClintock effect, is an alleged process whereby women who begin living together in close proximity experience their menstrual cycle onsets (the onset of menstruation or menses) becoming more synchronized together in time than when previously living apart. "For