Yep. When women are housed together, i.e. Convents or boarding schools, the menstrual cycle will happen for them all within 4-5 days. Can you imagine the impact of PMT in the week before

Flying across time zones upsets the body. I found when on holiday abroad even if I wasn't due a period, a change of water would bring it on

I tend to read a Very Good Book with a cuppa in my bath
