I started waking up at three in the morning with my hands completely numb, like they belonged to someone else. It scared me enough to look it up, and what I found was a lot less scary than I expected. Usually it is just how you sleep, and a small change fixes it.

It Is Usually Pressure or Position

When you sleep with your arm bent sharply or your wrist curled, you pinch the nerves and blood vessels that feed your hand. The numbness is a signal, not a disease, at least most of the time. The fix starts with how you hold your body.

What to Change

• Stop sleeping on your arms. Tucking a hand under your head or body cuts off feeling.
• Keep wrists straight. Curled wrists compress the nerve in the carpal tunnel.
• Try a different pillow. Too high or too low twists your neck and shoulders.

When It Is More Than Position

If it happens every night no matter how you sleep, or you also get tingling during the day, it is worth a doctor visit. Carpal tunnel syndrome and a few nerve issues cause the same feeling, and catching them early matters. My numbness stopped almost completely once I stopped sleeping with my arm under my pillow, which had been my habit for years.

A wrist splint at night keeps your wrist neutral if you cannot break the curl on your own.