Raggie, I have something for you. Sunlight regulates mood. The more sunlight you get in your eyes, the more your mood will be elevated. There is less sun in Winter, believed to be the cause of "Winter Doldrums."
Figure out exactly when the sun rises where you are, not necessarily the actual sunrise, but when you can see the sun directly. Bundle up and meet the dawn, and get yourself at least an hour of direct sunlight every day you can. If it's too cold, figure out if you have a window where direct sunlight enters and when that happens and for how long. Lie down there and close your eyes with the sun on your face. Do this religiously. You will feel better.
Conversely, if you just can't get to the sun, use your flashlights. Close your eyes, and shine them right on your face from point blank range until you feel legitimately silly. I find incans work best, but probably just bias... white light is white light.
The blue light (in sunlight or computing device) will reset circadian rhythms, so if you're sleep is off, be aware. If you see the sunrise, your clock will reset and you'll fall asleep that evening, or if you just get morning light in your eyes after waking. Sleep patterns are closely related to mood as well... but it's a strange thing: not enough sleep depresses mood, too much sleep depresses mood, while a few days of sleep deprivation will simultaneously elevate mood but will also tend to make one feel like crap the longer the deprivation continues, and just the right amount of sleep... 6-9 hours, and a good night's sleep, regularly, will help maintain mood.
Try not to dwell on your mood. Pretend you are your own friend and distract yourself... keep busy. Equipped with these simple tips regarding sunlight, blue light and sleep patterns, you'll be on top of the world in no time.