Why do my hands tingle like pins and needles while i am sleeping?

Nerve: You may be putting pressure on you arm's nerve if you sleep on you side, or sleep with your arm over your head.

Nerve compression: While sleeping, the hands and elbows can be placed in a static position for a prolonged period of time and this can cause carpal tunnel syndrome (compression of the median nerve at the wrist) or cubital tunnel syndrome (compression of the ulnar nerve at the elbow). Both can result in night time numbness & tingling. Best to have it checked by a hand surgeon to assess severity and render treatment