I personally turn into a dead zombie of death over the winter months. Living at the 45th parallel in the stupid little microclimate of the Portland metropolitan area guarantees that I can’t get a decent amount of UV in my face and so my vitamin D levels drop and I have to (literally) dose myself with reptile lamps in order to keep my immune system functional and from falling into a deep well of emotional pain for 6 months (it takes ~3 months after summer ends for me to deplete my vitamin D reservoirs and for my energy levels to begin drooping).
While some folks like Christmas, for me it always spells the beginning of the Season of Doom and Gloom, and I much prefer what happens at the end of the holiday season, after the solstice and as we go into spring with days lengthening (but before the sun god even starts thinking about showing us his hallowed face again.
Which is why I light the Christmas tree on fire every year.
Happy Imbolc!