Sometimes, when I’m faced with a living-off-the-grid problem, I try to imagine how my ancestors would have dealt with it. The current case in point: keeping my head warm while sleeping in an unheated van.
One solution is to simply pull the bedding over my head, leaving an opening for my face. But I move around in bed and the covers can end up elsewhere.
So I’ve adopted that classic Victorian habit of the night cap. Not the glass of distilled spirits before bed. The head covering one wears to bed. As in “Ma in her kerchief and I in my cap / Had just settled down for a long winter’s nap.” Except rather than the long pointed stocking cap Ebenezer Scrooge is always depicted wearing (how did they avoid getting tangled in those things?), mine is an ordinary knit beanie. Warm head, no problem.