Every October like clockwork. You start canceling plans. By November, getting out of bed feels like dragging yourself through wet concrete. December through February is a haze of oversleeping, overeating, and doing the minimum. March rolls around and you come back to life.
That's not "the winter blues." That's Seasonal Affective Disorder, and living in the Pacific Northwest makes you a prime target because we get approximately 17 minutes of sunshine between October and April.
The mechanism: less sunlight disrupts serotonin production and your circadian rhythm. Your brain literally has less of what it needs to maintain normal mood. This isn't weakness. It's photobiology.
Light therapy works. SSRIs work, especially started proactively before the season hits. Morning outdoor exercise attacks both mechanisms at once.
If you've noticed the pattern, start planning now. The worst time to start treating seasonal depression is when you're already too depressed to do anything about it.