Genuinely curious how do you guys deal with seasonal depression?

Like i go by just fine like a normal person for at least four to five days and then bam. I get suck into this whirlpool of excruciating loneliness which comes out of no where and you know the usual sad stuff. But then after a good three days i get back to normal. And then the cycle keeps repeating. Is this normal? How do you people deal with loneliness? How do you guys cope? (also suggest angst bl manhwas. Thank you)