What does it mean if my right hand goes numb while sleeping?

A possibility: It may indicate a neuropathy depending on where exactly on the hand and arm you note numbness. Carpal tunnel syndrome (a type of median neuropathy), ulnar neuropathy, or radial neuropathy may be present. Try to avoid pressure on the arm and hand while sleeping including awkward posturing. Keep it straight while asleep. If you note weakness or pain, please consult a neurologist. Hope that helps!