Whether you’ve sat cross-legged for too long or slept on your arm, you’re likely familiar with that pins-and-needles sensation when a limb “falls asleep.”
It may feel really weird and uncomfortable but, in most cases, this phenomenon is completely normal.
If you’ve ever wondered what it’s called when your foot or arm falls asleep, or you want to understand what’s going on when this happens, read on.
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What Is It Called When Your Foot Falls Asleep?
The technical term for when a limb falls asleep is paresthesia. It occurs when sustained pressure causes one or more of the nerves in a body part to become compressed.
This temporarily interferes with the nerve’s ability to communicate with your brain. As a result, you experience numbness in the affected limb, along with a sensation of burning, tingling, skin crawling, or “pins and needles,” as the National Institutes of Health describes.
Common factors that can trigger paresthesia include crossing your legs, sitting in the same position for an extended period of time, and sleeping on your arm or hand.
Fortunately, the odd feelings that accompany paresthesia typically clear up once the pressure on the nerve is removed.
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Why Does Your Foot Fall Asleep?
In most cases, paresthesia is temporary and harmless. Sometimes, though, paresthesia can signal an underlying condition.
In these cases, paresthesia is usually chronic and not the result of simple mechanical pressure. Instead, chronic paresthesia tends to be a symptom of a neurological disease or nerve damage.
Causes of chronic numbness and tingling in the limbs can include:
- Multiple sclerosis
- Carpal tunnel syndrome
- Brain tumors or spinal cord tumors
A pinched nerve also can cause a limb to fall asleep, depending on where it’s located. If you experience feelings of pins and needles often, you should contact your doctor.
Otherwise, if your leg falls asleep and you want to know what to do, try:
- Switching positions often
- Not crossing your legs for long periods of time
- Sleeping on your back rather than your side
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