Another sign is aversion to social interaction, a strong disinclination to reply to a message now. "I'll do it later."
So, that's signs. Cause could very well be the extended exposure to my parents. I recall having a depression after being with them last summer: dysfunction tied up with death. SAD seems a clear possibility though, and i know how to work that. (Move south of the 36° parallel, comes to mind.)
Next steps: do the laundry. I think that's gotta happen. Not that it's backed up or anything, but one small load has been on my list to do for a few days, and i haven't managed. Did get a walk in on Sunday: need to walk today. That might mean getting a digital book and walking around the pool or - there was something i was going to watch while on the (stationary) bike. Christine is practicing mandola in the evening, so i should move the bike out to the deck so as not to disturb her.