Who I'm the only one in the house I sometimes will, or just wear my house coat. I'm a woman, so it's not so much about freedom or sperm count or whatever, it's just that most clothing is meant to hang well when you're standing or sitting. When you lie down, and if you toss and turn in your sleep at all, most clothing is going to bunch up in uncomfortable ways, even sleepwear.
My room also gets very hot during the summer and very cold in he winter, so I typically won't in colder months but typically will in warmer ones.