Numb Hands at Night: Is It Really Carpal Tunnel Syndrome?

There are several possible explanations for night-time worsening of numbness. At night the hands and wrists often take up positions that increase pressure on the nerves: wrist flexion (for example when the hand is tucked under the pillow), elbow flexion (the ulnar nerve) or raising the arms above the head (the thoracic outlet region). Lying still also favours the accumulation of fluid in the tissues of the hands, and fewer movements mean the nerve stays compressed for longer because there is no stimulus prompting a change of position. Not every one of these hypotheses is fully supported by studies, but the dependence on position is well documented.

What follows from this? First, nocturnal tingling of the hands is a very common phenomenon and does not always mean disease — it also occurs in young, healthy people. Second, sleeping position matters, which gives a first, safe intervention: avoiding sleeping with the wrists and elbows strongly flexed. It should be remembered, however, that the study is cross-sectional and based on a questionnaire, so it shows an association and does not prove that a change of position will cure the symptoms. We rate the evidence as preliminary.

The distribution of numbness is one of the most useful clues. The median nerve (carpal tunnel syndrome) supplies sensation to the thumb, index finger, middle finger and the half of the ring finger on the thumb side; the ulnar nerve to the little finger and the other half of the ring finger; the cervical nerve roots have their own areas, for example the C6 root usually the thumb and index finger, C7 the middle finger, C8 the little finger. In practice the distribution is imprecise, but it helps to form a suspicion.

The table is an aid and does not replace an examination. It is also worth knowing that nerve compression may occur at several sites at once (for example the median nerve at the wrist and irritation of a root in the neck), which doctors call double crush syndrome. A slight improvement after one intervention does not therefore always mean the whole cause has been explained.

According to the review by Padua et al. (Lancet Neurology, 2016) carpal tunnel syndrome is the most common peripheral nerve entrapment syndrome worldwide. Its symptoms and examination findings are widely recognised, and both conservative and surgical treatment are available. The authors note, however, that there is little evidence as to which approaches to assessment best guide the choice of treatment; nerve conduction studies (electrodiagnostics) and nerve imaging provide additional information on the degree of damage, but their exact benefit to patients is unknown.

What does this mean for a person with night-time numbness? The classic picture — numbness of the thumb, index and middle fingers, waking one at night, easing after shaking the hand — strongly suggests carpal tunnel syndrome. When, however, the symptoms involve the little finger, appear together with neck pain, worsen with head movements or involve both hands and feet, another or an additional cause should be sought. We write about carpal tunnel syndrome itself — its mechanism, treatment and surgery — in a separate article and in an entry in our knowledge base.

Factors associated with more frequent carpal tunnel syndrome include obesity, diabetes, hypothyroidism, pregnancy, repetitive manual work and wrist injuries. The evidence for individual factors varies in strength — two of them, diabetes and hypothyroidism, are discussed below because they can be tested by blood tests and influence diagnostic decisions.

It follows that in a person with diabetes night-time numbness of the hands is more often linked to carpal tunnel syndrome, but diabetes can also cause polyneuropathy, which produces 'glove and stocking' numbness — so telling them apart requires an examination. We remind you that diabetes increases the risk of carpal tunnel, and does not mean that every numb hand is carpal tunnel. We write about diabetes in our knowledge base.

The link between hypothyroidism and carpal tunnel syndrome is weaker than is often assumed. In the meta-analysis by Shiri (Muscle & Nerve, 2014) covering 18 studies, uncontrolled analyses pointed to a strong association (for hypothyroidism an effect of 2.15; 95% CI 1.64–2.83), but after accounting for confounders the effect fell to 1.44 (95% CI 1.27–1.63), and the author noted possible publication bias and found only a modest association. The practical conclusion: measuring TSH is sometimes justified in the work-up, especially when other symptoms of hypothyroidism accompany the numbness (fatigue, cold intolerance, constipation, weight gain), but hypothyroidism is not the main cause of most cases of carpal tunnel. We write more about the thyroid in our entries on TSH and thyroid hormones and on hypothyroidism.

Vitamin B12 deficiency can damage peripheral nerves and cause tingling and numbness of the hands and feet, often on both sides. The review in American Family Physician (Patel and McGuirk, 2025) indicates that B12 deficiency occurs in about 2–3% of adults in the US, and that risk factors include malabsorption, a poor diet, certain drugs (including metformin and proton pump inhibitors) and older age; symptoms may include fatigue, 'brain fog', depression, peripheral neuropathy and ataxia. The authors recommend testing when there is at least one risk factor and one clinical feature; a total B12 below 180 pg/mL is diagnostic of deficiency, and borderline values (180–350 pg/mL) call for a methylmalonic acid measurement. We write separately about B12 deficiency in the context of metformin, and about the vitamin itself in an entry in our knowledge base.

Cervical radiculopathy is irritation of a nerve root, most often by a disc protrusion or narrowing of the intervertebral foramen. It produces pain radiating from the neck to the arm and tingling and numbness in the area of a particular root, often worse on tilting or turning the head. Clinical assessment is based on the history and neurological examination; the review by Thoomes et al. (Spine Journal, 2018) showed that evidence on the accuracy of physical tests is limited, and the only test assessed in more than one study was Spurling's test, with high specificity (0.89–1.00) and variable sensitivity (0.38–0.97). The authors suggest that, when consistent with the history, a combination of Spurling's test, axial traction and the arm squeeze test increases the likelihood of radiculopathy, and four negative neurodynamic tests with the arm squeeze test may help to exclude it. We write about neck pain and its diagnosis separately.

Compression of the ulnar nerve near the elbow produces numbness of the little finger and half of the ring finger, which worsens with a bent elbow — the kind we often adopt during sleep or a phone call. The diagnosis rests on the distribution of symptoms, examination and, if needed, a nerve conduction study. Conservative treatment includes avoiding flexion and prolonged leaning on the elbow (for example a night splint or soft wrap that keeps the elbow straight); evidence for individual methods is, however, limited, and the decision is made by the doctor.

Thoracic outlet syndrome (compression of the brachial plexus or vessels in the region between the collarbone and the first rib) is rarer and can be difficult to recognise. Typically symptoms worsen on raising the arms or carrying loads and may involve the whole arm. Its diagnosis requires exclusion of other causes and is often difficult, so specialist assessment is needed when it is suspected. We do not give figures here for the frequency of this syndrome because we do not rely on a verified source in this regard.

A splint holding the wrist in a neutral position is one of the most frequently used methods of self-treatment of night-time numbness, provided the cause is carpal tunnel syndrome. The evidence for its effectiveness is, however, modest.

In practice this means: a night splint is a reasonable, cheap and low-risk trial in a person with typical symptoms of carpal tunnel, but a sure effect should not be expected. If after a few weeks there is no improvement or symptoms are getting worse, it is not worth continuing to assume that the problem lies only in the wrist. A splint also does not treat cervical radiculopathy or polyneuropathy.

The first step is the history (distribution of numbness, times of day, triggering positions, coexisting diseases, drugs) and a neurological examination of the hands and neck. A quick aid is to mark the area of numbness on a hand diagram completed by the patient. Further investigation depends on the suspicion and is not always needed in a person with typical, mild carpal tunnel syndrome.

The review by Padua et al. shows that carpal tunnel syndrome can be diagnosed quickly and patients respond well to treatment, but there is a lack of certain evidence on how best to combine clinical, functional and anatomical data when choosing treatment. When there are differential doubts it is therefore worth seeing a neurologist or a doctor who deals with diseases of the locomotor system. We write more about the role of MRI in our entry on MRI.

Remember that self-management makes sense for mild, intermittent symptoms. When numbness is getting worse, is constant, is accompanied by weakness of the hand or comes with other neurological symptoms, do not try to improve the situation yourself — contact a doctor.

See a doctor (within days to weeks) if the numbness is constant, getting worse, involves both hands or also the feet, is accompanied by weakness of grip, dropping objects, wasting of the hand muscles or pain radiating from the neck, or when symptoms last longer than a few weeks despite a change in sleeping position and the use of a splint. Delay in treating nerve compression can lead to permanent damage, so progressive weakness is a reason for earlier assessment.

Night-time numbness of the hands is a common and usually harmless symptom, but it is worth identifying its cause, because the treatment depends on it: treatment of median nerve compression differs from that of the ulnar nerve, a cervical root and polyneuropathy. The distribution of numbness, its dependence on position and coexisting diseases are the best clues. When symptoms are atypical or progressive, medical assessment is a better route than further home trials.