Can sleeping with your leg hanging off the bed make your foot fall asleep or be numb? my 6 year old son has been waking up to a sleeping leg and numb foot sensation that resolves after a minute. he sleeps on his back and at times half off the bed?

Minor problem: Amazingly, 6 yo sons are very resilient. A compression of a nerve will readily reverse, but in older folks, there could be residual neurapraxia on occasion, even when falling asleep with legs crossed. So, do not worry about your child. He should do quite well, and assuming absence of nerve disease in your family, there is truly almost no risk.