My right shoulder keeps falling asleep. what could be the causes?

Neck problem: (C4 or C5 issue) or supraspinatus or axillary nerve. Other symptoms. (Weakness of the biceps or deltoid muscles?) Pain in neck radiating to shoulder or hand?. Does your radial pulse in the wrist do away when you lift your arm to the side (vascular thoracic outlet syndrome?) Any rash? If this problem persists you are going to have to see a doctor who may order a scan or refer you to a neurologist

Pinched nerve: Depending on how long you have this symptom, try changing the position of your sleep to see if it goes away. Otherwise a visit to your doctor or urgent care would be helpful.

Neuropathy: The cause of an extremity "falling asleep" usually is compression of a nerve(s) that supplies the extremity. If the symptom involves the shoulder the nerve is often being compressed as it leaves the spinal cord, by either a bulging or herniated disc or bony projections called osteophytes that occur with aging. The condition is called cervical radiculopathy. SEE: http://bit.ly/1yPwhcG