Growing up I always just slept in whatever I wore that day. It didn't matter to me.
When I lived on my own, I would sleep however I felt that day. Some days I slept in what I wore that day. Some days I slept in designated home only clothes (superhero t-shirt, and either sweatpants or basketball shorts). Some days I slept without any clothes on. Some days I slept without a shirt on. For some reason, I actually really like sleeping in just jeans, which isn't something I ever see other people say because most people find jeans really uncomfortable to sleep in. And then some days I slept without pants on.
Now I'm living back at home, so I don't get the freedom to sleep how I want since people don't respect privacy in this house and my bedroom door can be unlocked from the outside with a coin or even a fingernail.
The only thing that remains consistent is I NEVER sleep with underwear on. Hell, the only time I ever really put underwear on is when I'm going to work. I go commando at home and I go commando in jeans.