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 study has ever found that menstrual cycles become strictly concordant, nevertheless "menstrual synchrony" is used to refer the phenomenon of menstrual cycle onsets becoming closer to each other over time. In a recent systematic review of menstrual synchrony, Harris and Vitzthum concluded, "In light of the lack of empirical evidence for MS [menstrual synchrony] "sensu stricto", it seems there should be more widespread doubt than acceptance of this hypothesis" (pp. 238–239). The experience of synchrony may be the result of the mathematical fact that menstrual cycles of different frequencies repeatedly converge and diverge over time and not due to a