It is a subtle difference that takes a long time to accumulate, and may be as much due to a kind of placebo effect (me believing I'm doing something that will help) as any actual pharmacodynamics. But over the years my seasonal mood disorder HAS moderated and vitamin D is one of the regular interventions I use.

Another thing that was enormously helpful for me was to purchase an alarm clock with a 'wake light' that begins slowly lightening the room about half an hour before the alarm sounds. That has made waking up much less painful and difficult during the long hours of darkeness and helped me maintain a more regular (and I hope) healthy sleep schedule.

Good luck, and don't forget that 'good' (i.e. healthy) effects and changes take a lot longer to normalize in your brain than the chemically-induced ones - persistence will pay off.

helpfully,
Bright

Eight months of little to no sun. Nope. I couldn't do that. The few months of constant sun wouldn't be enough to sustain me through the darkness.

Have you looked into light therapy lamps? I have no idea if they're effective, only that they exist. Also, maybe deck your house out with all sorts of other types of lighting. Christmas lights. Lava lamps. Whimsical lamps. LED lamps that change colors.

Just over two weeks until the shortest day of the year. Good luck!