i did know someone who slept with a wrist brace on to prevent his hands
curling up at night. I have had numbness in my hand, and MRI determined it to be cervical (neck) nerve problem. I was cautioned not to get a "neck adjustment" from a chiropractor, or other well-meaning
person.

How exactly can one control thier posture while asleep? YOur conscious mind is not calling the shots if you are sleeping.