I wear briefs or trunks, but I guess I only sleep in trunks. Sleeping in briefs feels like not enough on. I mean when I don’t wear pajamas, that is. For sports, I do track, so I’m wearing shorts and a T-shirt. The type of underwear doesn’t really matter. I will say most guys in my P.E. class or on the team wear boxers or boxer-briefs, but not everyone.