in India. Chhaupadi is a social practice that occurs in the western part of Nepal for Hindu women, which prohibits a woman from participating in everyday activities during menstruation. Women are considered impure during this time and are kept out of the house and have to live in a shed. Although chhaupadi was outlawed by the Supreme Court of Nepal in 2005, the tradition is slow to change. Women and girls in cultures which practice such seclusion are often confined to menstruation huts, which are places of isolation used by cultures with strong menstrual taboos. The practice has recently come under fire due to related fatalities. Nepal criminalized the practice in 2017 after deaths were reported after the elongated isolation periods, but "the practice of isolating menstruating women and girls continues." Beliefs around synchrony Effects of the moon Even though the average length of the human menstrual cycle is similar to that of the lunar cycle, in modern humans there is no relation between the two. The relationship is believed to be a coincidence. Light exposure does not appear to affect the menstrual cycle in humans. A meta-analysis of studies from 1996 showed no correlation between the human menstrual cycle and the lunar cycle, nor did data analyzed by period-tracking app Clue, submitted by 1.5million women, of 7.5million menstrual cycles, however the lunar cycle and the average menstrual cycle were found to be basically equal in length. Cohabitation Beginning in 1971, some research suggested that menstrual cycles of cohabiting women became synchronized (menstrual synchrony). Subsequent research has called this hypothesis into question. A 2013 review concluded that menstrual synchrony likely does not exist. Work Some countries, mainly in Asia, have menstrual leave to provide women with either paid or unpaid leave of absence from their employment while they are menstruating. Countries with policies include Japan, Taiwan, Indonesia, and South Korea. The practice is controversial due to concerns that it bolsters the perception of women as weak, inefficient workers, as well as concerns that it is unfair to men, and that it furthers gender stereotypes and the medicalization of menstruation. Menstruation activism Menstruation activism has become more prominent during third-wave feminism, with a range of arguments being made across global scholarship and cultures. Much of the menstruation activism in the West has centered on arguments against what many feminists believe to be the misuse of menstruation to 'prove' female biological inferiority.