PMS. Seriously, though. I have some major moods while I'm PMS-ing. I have to be up for work in about two hours, and I am sitting in bed, fully clothed, teary-eyed, and illogical. You know what's ridiculous is when your logic is reminding you that you have nothing to be sad about, but something... a chemical/hormonal imbalance, perhaps, is making you feel cranky, irritable, and sad. The crankiness and the irritability are manageable, it's the sadness that gets out of hand.
At least for me. Where is all of this gloom and doom coming from?