Happened a lot to me to -- kinda why I gave up on sleeping in PJs or anything else. When I was a teenager (15-18) I started to notice that I would wake up totally naked -- my PJs or sweats were always on the floor by the bed or even on the otherside of the room when I woke up in the morning -- with no recollection of having stripped down during the night.
After a while I just gave up and went to bed naked. Now I sleep naked pretty much all the time.
The odd time I do wear something to bed -- longjohns in the winter -- I will still sometimes wake up in the morning to find myself butt naked and the longjohns on the floor.
I don't worry about it if I am bunking with another dude -- figure another dude shouldn't be too shocked to see another dude naked in the morning -- but if I have to stay at a female relatives place or share a room with a woman for some reason (recent trip south) I get a bit nervous that they'll freak if I jump out of bed in the morning butt naked -- so I tend to wake up and check for my gear right away. lol
WellHung83 --> I do the same thing -- pad around at home with just a tank top or Tshirt with nothing below but my bare butt. Not sure why I like it -- probably just like the freedom of nothing below but the warmth of a shirt up top.