pfft. . .getting undressed is fun. . .hell. . .most of the time i'm so damn horny, even if she was covered with thorns i'd still jump on her. . .i'm a d00d, i don't let little things get in my way. . .
When I'm alone - never. I have no idea why, I just never got in the habit of sleeping nude.
With someone else - I have no problem falling asleep naked. I like the feeling of skin on skin. BUT...I tend to get up at like 5am and put all my clothes on (socks included) and then crawl back in bed. That must be so annoying.