Menstrual synchrony by chance when there is menstrual cycle variability. Yang and Schank argued that when there is cycle variability (i.e., either women have irregular cycles, have cycles of different frequencies, or both), most women will have the opportunity to experience synchrony even though it is a result of cycle variability and not a result of a mechanism such as the exchange of pheromones. For example, consider two women A and B. Suppose A has menstrual cycles that are 28 days long and B has cycles that are 30 days long. Suppose further that when A and B become close friends, B
Menstrual cycle occur as a result of adopting a restricted diet, as well as engaging in a high amount of exercise. Finally, the cycle is affected more by a vegetarian diet compared to a non-vegetarian diet. Studies investigating effects of the menstrual cycle on alcohol consumption have found mixed evidence. However, some evidence suggests that individuals consume more alcohol during the luteal stage, especially if these individuals are heavy drinkers or have a family history of alcohol abuse. The level of substance abuse increases with PMS, mostly with addictive substances such as nicotine, tobacco and cocaine. One theory behind this suggests this