Hand numbness while sleeping has a variety of causes, including sleeping position, carpal tunnel syndrome and diabetes, according to WebMD. Other possible causes include vitamin deficiencies, alcoholism, infections and injuries.
Numbness or tingling in the hands occurs when nerves in the arm or wrist are compressed or damaged, according to WebMD. One of the simplest causes for nerve compression during sleep is when the arm is bent for a prolonged time or rested underneath another part of the body. In this case, the tingling sensation dissipates on its own after the pressure is removed.
Nerve damage is caused by a number conditions, as stated by WebMD. Carpal tunnel syndrome is a condition in which excessive pressure is applied to the median nerve, which runs through the length of the arm and into the hand. This pressure can be caused by swelling due to illness, pregnancy or prolonged, repetitive movements of the wrist.
Another condition that can cause hand numbness is peripheral neuropathy, which is nerve damage caused by illness, infection or exposure to toxins. Diabetes is one of the most common causes of peripheral neuropathy, which affects about one in three diabetic patients. Though it may be a nuisance, hand numbness alone is seldom a sign of a life-threatening condition, such as a stroke, Mayo Clinic notes.