I sometimes sleep with legs covered and sometimes not. During thos latter times, a sheet comes in real handy to seperate body parts and minimize sweating. I'm sure that could work if sleeping nude too. The only thing is I'd need to have the sheet further up on my legs and might prefer not to have the sheet in my groin area. To each, their choice.
(When my sons were young, they'd see that their couson slept nude and it bothered them: "Who'd want to sleep in the bed when Greg's bare butt has been on it!")