I'm also having this issue in 41.68 (without any alt-tabbing). Me and another player went to sleep in a ~55 degrees Fahrenheit safehouse wearing decent insulation, and we were both instantly awoken (there was a 10 minute tick of in-game time). The other player got maximum hypothermia, and I got maximum hyperthermia, apparently because I was slightly over my weight limit? So then I removed my excess weight, we both bundled up with warmer clothes, and tried sleeping again, but we again woke up, both with maximum hypothermia this time.
I don't know if this makes a difference, but the server was on real-time scale, with the default 40x sleep speed multiplier.
This bug has made sleeping straight up impossible.