>>1216319"Also make sure to wear very little clothing or go naked in it to maximize body heat (seriously do it or freeze)"
Worst advice ever! 1), doing this gets your dead skin and body oils ground into your sleeping bag degrading the insulating properties over time and just making things nasty. 2) your body's circadian cycle is lowest around 4 am which means waking up cold and needing to piss like a race horse.
Best advise is eat something before bed , stick a nalgene of hot water in your fart sack. wear a hat and neck gaiter clean socks and at least a wool 1st layer top and bottom. Place your clothes under your bag and above your sleep pad to keep them near and unfrozen, It sucks but winter camping always contains some suck.