The notion that women's menstrual cycles sync up is a common belief, but experts assert that it lacks scientific backing. Dr. Jody-Ann McLean, a women's health expert, explains that the idea originated from a small 1970s study that has not been successfully replicated. A more recent analysis from the University of Oxford found that, rather than syncing, women's cycles tend to drift apart over time. Kat Grassetti, a clinical director at Monima Wellness Center, notes that while friends or roommates may experience coinciding cycles, this is primarily due to chance rather than any biological synchronization. The misconception may stem from confirmation bias, where people remember instances of alignment while overlooking the many times their cycles do not match. Overall, there is no evidence or mechanism to support the idea of menstrual synchrony, making it a fascinating yet unfounded concept.