Fester, Fester, Fester, Rot, Rot, Rot... That was a funny line in a movie that I saw sometime last week when I couldn't sleep. I have been sleeping less than usual, which for me is not much to begin with. One way to stop levitating in your sleep is not to fall asleep at all... that's advice for those of you that have that similar problem. Also, consider padding the ceiling, just in case you do fall asleep. 
~cheers