“Why Your Hands Go Numb at Night”

If daytime typing isn’t to blame, what explains the classic story—“I wake up at 2 a.m. with my hand

asleep”? The answer lies in prolonged wrist flexion during sleep.

When the wrist bends forward, the carpal tunnel space narrows and pressure on the median nerve

rises dramatically. Pressures double or triple in 45–60° flexion, comparable to provocative test levels.

Many patients curl their hands under a pillow or chest—a “Phalen’s position” maintained for hours.

Those same patients often note their nighttime symptoms disappear when they wear a brace or

consciously keep wrists straight.

Research in sleep biomechanics and wrist thermography supports this mechanism: median-nerve

compression peaks during flexed postures, then subsides upon awakening and shaking out the hand.

So while your workday setup deserves ergonomic attention, your sleeping position may be the single

biggest—and most overlooked—factor aggravating carpal tunnel pressure.