Mate of mine fell asleep on his arm on the stairs once, woke up some 7 hours later to a completely dead arm. Doctor said he starved the muscle of oxygen, and had atrophied it (if that's possible??). He spent the next 2 weeks regaining the strength in training... lifting pints as he was signed off work. 2 weeks, 100+ pints and 10 days of statutory sick pay later... 
