Yeah, there are times where I wake up in either a grumpy or depressed mood. It helps usually if I have an idea of why I'm feeling that way. If it was a bad dream or a bad night's sleep, or just overall fatigue, I try to correct it and move on. (extra coffee, nap, early dodo, etc)
When I'm particularly irritable for no apparent reason (and notice myself being not so nice) I try to tell myself that I'm being grumpy because of me, not the person who's irritating me, and that usually forces me to be a bit less snippy(even when I feel like I still want to be).
But there are times when I'm just blah and it has to wear off on its own. Usually doing something fun/distracting helps, but it has to be something I decide to do (as opposed to someone trying to perk me up).
I do notice too that getting some sunlight really helps my mood. Being outside or even inside looking out on a beautiful, crisp, day always helps my mood. Long stretches of cloudy days can get me down. Supposedly halogen lights are good substitutes for light on crappy days.
I think on the days you're allowing yourself to be down, you probably just need some time to regenerate and give yourself a break. Perhaps you're not drawing enough internal energy to turn it around. And I'm sure some of it is hormonal, unfortunately...
affirmations are powerful, afterall, in most cases we can choose how we're going to feel/react to certain situations.
good luck...lots of rambling on my part.
