Many of us will have woken up in the morning with a numb sensation in our feet. Sometimes, our feet ‘fall asleep’ during the day, leading to the strange tingling sensation.
Why does this happen? We look at the causes of foot numbness during sleep, and when to be concerned.
Causes of foot numbness during sleep
There are many different things that can cause foot numbness, so the answer isn’t always straightforward.
The actual numbness and feeling of pins and needles happen when the nerves in your leg stop communicating with your brain. The medical term for this feeling is paresthesia and it is a sign that your foot has ‘gone to sleep’.
Paresthesia is very common, and most causes are harmless. But sometimes, it can be a sign of a problem.
Transient versus persistent paresthesia
Paresthesia is referred to as transient or persistent. Transient paresthesia is temporary and will go away after a short time. It’s usually harmless and happens when the way you position your body puts pressure on a nerve or restricts blood flow to the leg (or other parts of the body).
For example, crossing your legs for a long time puts pressure on the blood vessels that are carrying blood to the nerves in your leg. When they don’t get enough blood flow, the nerve’s function is interrupted.
If your foot is numb when you wake up, it’s probably because you have slept in a position that has limited blood supply to your foot. Stretching or moving your leg is usually enough to resolve it.
Transient paresthesia can also happen if you knock a part of your body against a hard object – think of the tingling sensation that happens when you knock your elbow, referred to as hitting your funny bone.
Persistent or chronic paresthesia doesn’t go away and is often a sign of an underlying condition that needs medical attention. The causes of persistent paresthesia tend to be one of the following:
- Circulatory causes
- Nervous system causes
- Metabolic and endocrine causes
- Infectious diseases
- Autoimmune and inflammatory diseases
- Toxic effects.
When to seek help for foot numbness
Most of us will experience numbness in our legs or feet at some stage. It’s a very common condition, usually caused by the way we are positioned. Moving or stretching will soon relieve the feeling.
But if you experience numbness in your leg, or any other part of your body frequently, or the feeling doesn’t go away, always talk to your doctor as it could be a sign of a more serious underlying condition.