How does a person know if mood swings is just having a period or if it is the beginning an episode. The irritability of a period can last for about a week before or on a period. Irristability may be a sign of depression or mania. If it lasts more then a two weeks it might be a mood swing of bipolar or schizo-affective disorder.
Irritability is a hard one because it can be a symptom of all three. To be able to make a decision is the longevity of it and what other symptoms it co exists with. Depression it has sadness. And mania it has increase energy less need for sleep.