I get it sometimes but assume it's my sleep position/arthritis. I always lie on my back initially and find it so comfy but don't seem to be able to get to sleep unless I lie on my side so assume my arms/hands get squashed at some point during the night in addition to being immobile. I had a phase of waking up with fingers bent which would take ages to straighten so goodness knows what I was doing in the night (that sounds rude, it's really not meant to!!!)!
Still working on training the cats to bring me a cuppa in bed...not holding out hope on that one though!