Many people suffer from their right arm randomly going to sleep. There is no one reason for this condition and only after your doctor has examined you can you know with certainty the cause.
Many people with pinched nerves suffer from their right arm going to sleep. With some people, the only pinched nerve symptom they have is when their arms go to sleep.
Sometimes when people have had minor strokes one of the lingering effects is that their right arm goes to sleep.
Wrong Mattress and Pillow
Many people that sleep on a hard mattress and or a thick pillow suffer from their arms going to sleep. Buying a softer mattress pad and a thinner pillow might do the trick.
Arms going to sleep are one of the first symptoms of a potassium deficiency. Potassium deficiencies can lead to severe medical problems that can be fatal.
Carpal Tunnel Syndrome
Many people suffer from Carpal Tunnel Syndrome which frequently causes arms to fall asleep. The right arm is especially susceptible as the number pad is on the right of the computer keyboard.