THE EMOTIONAL UPHEAVALS of PMS are so well known, the stuff of stereotypes. Who hasn’t heard of the woman so she shifts from being irritated to weepy in the blink of an eye? one who rages over the smallest incidents, her anger completely of proportion to whatever set her off? It’s a common stereotype, many women have been in those shoes. But why does this emotional disorder happen to women, and what can be done to alleviate it