Three in the morning, and your right hand is numb, with pins and needles from the thumb to the middle finger. You jolt awake, shake your hand a few times and reach for the bottle of medicated oil by the bed to rub into your wrist, still thinking the numbness comes from poor circulation and that warming it up will make it pass. Once the numbness fades, you go back to sleep. In the morning your hand feels a little clumsy holding the toothbrush, and by noon you have forgotten about it.
The tunnel in your wrist gets tighter while you sleep
On the palm side of the wrist, the tendons that bend the fingers and the median nerve pass together through a narrow tunnel called the carpal tunnel. The median nerve carries sensation from the three and a half fingers on the thumb side and controls the muscles in the fleshy mound at the base of the thumb (the thenar eminence). The little finger is served by a different nerve, so it usually does not go numb. When the median nerve is squeezed in this tunnel, which is carpal tunnel syndrome, the numbness often wakes people in the night, sits in the thumb, index finger and middle finger, and eases when they shake the hand. The condition can be diagnosed quickly and usually responds well to treatment (Padua and colleagues, 2016).
At night, many people sleep with the wrist bent under the pillow, the arm curled around a body pillow, or a cheek resting on the back of the hand. A wrist bent for hours makes the tunnel tighter, with no movement to open it up again, so the numbness tends to come between midnight and morning and eases as soon as you shake the hand.
Blood sugar, the thyroid and the months of pregnancy
Diabetes, an underactive thyroid (hypothyroidism) or the last months of pregnancy can make the tissue in the carpal tunnel swell, or make the nerve less able to cope. People with numb hands at night, especially numbness in both hands or in the feet as well, should have their blood sugar and thyroid checked when the doctor sees a need. In pregnancy, the numbness usually eases gradually after the birth, but if the hand is clearly weak you should still get checked.
Numbness from the wrist, or from the neck
The median nerve is formed from nerve roots in the neck, so when a root is irritated, the hand can go numb in exactly the same fingers. A few things you can notice yourself:
- Numbness that stays within the hand, the little finger is fine, the neck does not hurt, and shaking the hand helps: this points to the wrist;
- If the neck is tired and sore, and the numbness runs from the neck over the shoulder and down the arm, getting worse when you tip your head back or turn it toward the numb side, think more of the neck;
- Waking up with both a stiff neck and a numb hand after a night on a high pillow, or lying face down with your head turned, means looking at both the pillow and the neck.
Kane and colleagues (2015) describe double crush, where a nerve is compressed in two or more places and the compressions add up to make symptoms worse. This diagnosis is still debated, but the authors advise keeping in mind that neck root disease can occur together with carpal tunnel syndrome. If one spot is treated and the hand is still numb, the median nerve may sometimes be pinched somewhere else as well, such as in the upper arm or at the elbow, as in the case of numb hands while driving.
Which kinds of hand numbness need nerve testing early
Put your two hands side by side, palms up, and look: if the mound at the base of the thumb is flatter on one side than the other, the nerve has already been damaged in its motor part. This usually comes with numbness that never fully goes away, a weak thumb, trouble doing up buttons, and dropping things. At this stage you should have nerve conduction studies; electromyography (EMG) shows how far the nerve fibers are damaged (Padua and colleagues, 2016), so that a specialist can discuss decompression surgery with you.
Numbness in both hands with clumsy hands and an unsteady walk needs an early neurological examination, because the spinal cord in the neck may be compressed. And if your mouth suddenly droops to one side, you have trouble speaking, or one side of your body suddenly goes numb or weak, call emergency services right away, because it may be a stroke; do not wait to see whether you just slept on your arm.
Muscle testing in the exact position you sleep in
At your consultation with Dr. Dinh Ngoc Duc (MD, MSc in Traditional Medicine), you will be asked to point to exactly which fingers go numb and at what time of night the numbness comes. The doctor examines your wrist, neck, sensation and reflexes in both arms, then uses muscle testing on the opponens pollicis. This small muscle brings the thumb across to meet the tips of the other fingers, and the median nerve only reaches it after passing through the carpal tunnel. The result is set beside a few muscles in the forearm and upper arm that also receive fibers from the neck roots. If only the thumb mound is weak, the wrist is more suspect; if the weakness spreads to the muscles higher up, the doctor looks up toward the neck or the elbow.
You lie down as you do when you sleep, with your wrist in its usual position, bent under your cheek or curled against your chest, and your head raised as high or as low as your pillow at home. The doctor then checks the strength of your thumb muscle in that position. The first time with the wrist bent, the next time with the neck tilted the way your pillow holds it, each time checking whether a thumb muscle that was strong becomes clearly weaker.
A night splint, the pillow and needles
When the wrist is the main problem, the first step is to keep the wrist straight while you sleep. A Cochrane review by Page and colleagues (2012) cites one low-quality study of 80 wrists, in which people who wore a splint at night were three times more likely to feel better after 4 weeks than those who had no treatment.
When the neck contributes, the doctor reviews your pillow height and sleeping position, and mobilizes the neck vertebrae if the examination shows a section of the neck not moving properly, one step in an Applied Kinesiology consultation. You are shown chin-tuck exercises to do at home.
Acupuncture uses points around the wrist crease such as Daling and Neiguan, with points at the back of the neck added when the neck is also contributing. Dong and colleagues (2023) found that acupuncture used alongside other treatments may also improve electrophysiological measures of the nerve, although the certainty of the evidence is still low. For people who are pregnant, the clinic does not use needles.
For people with numb hands who also often have spells of blurred or dimming vision, the doctor thinks of a blood deficiency pattern (血虚 / 血虛, xuè xū). Traditional medicine explains that when you lie down at night the fingertips get even less blood to nourish them, so the numbness is worse at night, and for this pattern the doctor prescribes an herbal decoction that nourishes the blood and opens the meridians. If treatment does not help, the doctor will refer you to a specialist.
Worth keeping
- Sleep with your wrists straight; don’t bend your hand under the pillow or rest your cheek on the back of your hand;
- Try wearing a splint that keeps the wrist straight while you sleep for a few weeks, and see whether you wake up less often because of numbness;
- Write down which fingers go numb, at what time, and whether the little finger goes numb;
- Once a month, put your hands side by side and compare the mounds at the base of the thumbs; if one side has flattened, go for nerve testing;
- If you are being treated for diabetes or thyroid disease, or you are pregnant, and your hands go numb at night, tell the doctor who is looking after you.
References
- Padua L, Coraci D, Erra C, Pazzaglia C, Paolasso I, Loreti C, Caliandro P, Hobson-Webb LD (2016). Carpal tunnel syndrome: clinical features, diagnosis, and management. Lancet Neurol 15(12):1273-1284. https://doi.org/10.1016/S1474-4422(16)30231-9
- Kane PM, Daniels AH, Akelman E (2015). Double Crush Syndrome. J Am Acad Orthop Surg 23(9):558-62. https://doi.org/10.5435/JAAOS-D-14-00176
- Page MJ, Massy-Westropp N, O’Connor D, Pitt V (2012). Splinting for carpal tunnel syndrome. Cochrane Database Syst Rev 2012(7):CD010003. https://doi.org/10.1002/14651858.CD010003
- Dong Q, Li X, Yuan P, Chen G, Li J, Deng J, et al. (2023). Acupuncture for carpal tunnel syndrome: A systematic review and meta-analysis of randomized controlled trials. Front Neurosci 17:1097455. https://doi.org/10.3389/fnins.2023.1097455
