@JassyRadlett, you haven't been a total arse. You're dreading the onset of the short days and in consequence you were having a rough day. That's allowed.
There are obviously people on this thread who are really struggling. I don't have diagnosed S.A.D., but it does affect my mood - especially during the month I hate most, November. And it is serious. Apparently the suicide level in northern Scandinavia spikes during these dark months. It isn't a triviality.
I do try to find small things which for me make the season more bearable. A real flame (log burner, fire pit) does a great deal for my mood and I've just ordered one of those orange sunset lamps: might try a S.A.D. lamp, too. It's sunny where I am. I intend to go out and enjoy that, even if it's only for a brief walk around the garden (still WFH until next week).
Hope you're feeling a little better today. Try to find as many strategies as you can to make the dreary season more bearable (I've just brought out my autumn candle). One November I went to a gig. I try to build in small things to look forward to.
This is not to say I know what it's like having the true condition of S.A.D.; but I do know about depression. Sometimes having a shower and washing your hair can feel like a marathon; I can well imagine S.A.D has a similar effect. But if the small stuff helps, a little ...
Hope you are having a better day today 