You wake up and your arm under the pillow feels foreign: heavy, as if filled with cotton wool, and those same "pins and needles" everyone has known since childhood are crawling through it. Within a few minutes it passes, and you forget about it until next time. But sometimes these sensations do not pass so quickly — and then it makes sense to understand where they come from.
When a nerve is simply compressed
The medical term for this sensation is paresthesia: tingling, itching, or burning of the skin without visible irritation. Its best-known variety is the feeling of "pins and needles" or an extremity "falling asleep", although there are rarer variants such as "ants crawling" under the skin. The most common, everyday cause of numbness is temporary restriction of nerve impulses caused by an uncomfortable position or "sitting too long" on part of the body. Relieving the pressure usually leads to gradual relief. A brief sensation resembling an "electric shock" can occur even from hitting the ulnar nerve. In older age, spinal disorders sometimes produce brief paresthesias when the head or body is in unusual positions.
Carpal tunnel syndrome is a separate story: pressure on the nerve in the wrist area that causes tingling, numbness, and pain in the hand and fingers. Symptoms often begin gradually, come and go, and are usually worse at night. The risk is higher if a person is overweight, pregnant, does work or a hobby involving frequent wrist bending or strong gripping, has arthritis or diabetes, has previously injured the wrist, or has relatives with this syndrome.
When the nerves themselves are affected
Peripheral neuropathy develops when the nerves in the extremities — the hands, feet, forearms — are damaged. The main symptoms include numbness and tingling in the feet or hands, burning, stabbing or shooting pain, loss of balance and coordination, and muscle weakness, especially in the feet. In the UK, almost one in ten people aged 55 and over has peripheral neuropathy.
Diabetes is cited as the most common cause: over time, high blood sugar levels damage the nerves. Other causes include physical nerve injury, viral infection (for example, shingles), side effects of certain medications, or excessive alcohol consumption. Chronic paresthesias can also indicate vitamin deficiency and malnutrition, metabolic disorders, poor circulation in the extremities due to atherosclerotic narrowing of blood vessels, and in rare cases, mercury poisoning. Without adequate blood supply, nerve cells cannot adequately transmit signals to the brain.
The most common type of neuropathy — polyneuropathy — begins with the longest nerves, so symptoms usually start in the feet and later seem to "rise" higher and eventually affect the hands.
What else can underlie numbness
- Hypocalcemia — a lowered calcium level, which can manifest as severe pain and paresthesias in the extremities.
- Fabry disease — a rare inherited metabolic condition that causes acroparesthesia.
- Deficiency and metabolic conditions — in particular hypothyroidism and hypoparathyroidism.
- Consequences of central nervous system damage — in people who have had a stroke or traumatic brain injury.
To understand the picture, a doctor may refer for nerve conduction studies, and to rule out a role of the central nervous system — for a computed tomography scan. If carpal tunnel syndrome is suspected, a nerve test in the wrist area, ultrasound, or MRI is sometimes ordered.
If numbness or weakness of an arm or leg suddenly affects one side of the body, the face is distorted, or speech is impaired — this is a reason to immediately call emergency services — 103 or 112.
You should see a doctor if symptoms worsen or do not pass, if there is pain, tingling, or loss of sensation in the feet, balance problems or weakness, and also if a wound or ulcer that does not heal appears on the foot. People at high risk of neuropathy, in particular those with diabetes, are advised to have regular check-ups. In general, the earlier peripheral neuropathy is diagnosed, the greater the chance of limiting damage and preventing complications.
What to write down before a visit to a neurologist
At the appointment, the doctor asks about symptoms and examines the arm or leg, so the most useful thing is to bring specifics rather than a general "it's numb". Write down which areas are numb and on which side; when it happens — at night, after exertion, in a certain position; whether there is pain, burning, weakness, or difficulty picking something up with the hand; how long ago it started and whether it changes over time. Add a list of medications you take, mention past injuries, viral infections, alcohol, as well as conditions such as diabetes, arthritis, or thyroid problems. These details are not a formality: they are what the doctor uses to chart the direction of the search.
This material is for reference and does not replace a doctor's consultation: numbness has too many causes to make a diagnosis from a text.
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This content is for reference and does not replace a doctor's consultation. Medical disclaimer