The sensation of a foot, leg or arm “falling asleep” is a familiar one. We have all ended up on a particular point, with a slightly numb limbs that need to be shaken up—maybe you’re a habitual leg-crosser, or always sleep on the top of your arm. While the numbness or tingling sensation that arises can sometimes be alarming (especially if it takes a while to go away), most of the time, it really is nothing to worry about.
When a part of the body is temporarily numb, it is usually because you have too much pressure on a nerve. Nerves work like electrical wires, sending signals from the brain to parts of your body, and back again, Glenna Tolbert, M. D., assistant clinical professor at the David Geffen School of Medicine at UCLA and founder and medical director of neurological and orthopaedic rehabilitation centre Tolbert Rehab, he tells HIMSELF. When there is pressure on a nerve for a longer period of time, the signals can’t travel as efficiently. It is a bit like putting a kink in a hose.
In addition to annoying numbness, pressure on a nerve can also cause the tingling, slightly painful sensation of “pins and needles.” “The nerve becomes hypersensitive after being pressed,” and is irritated, Orly Avitzur, M. D., editor in chief of Neurology Now, the American Academy of Neurology patient magazine, and fellow of the AAN, he tells HIMSELF.
Many of the nerves in your arms and legs are superficial, or close to the surface of your skin, “If you look at your wrist, you can see the tendons and blood vessels. The nerves will be performed there, too,” Tolbert explained. Some of the nerves in your arms and legs are actually very easy to compress by simply them.
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“One of the common nerves affected for women is the nerve that sits outside of the knee, the peroneal nerve,” Avitzur says. “It’s not about one leg over the other.” Leaning on your arm, or sitting on your foot are also common triggers for a body-part siesta. It’s all very normal and should disappear within 30 seconds after removal of the pressure.
A more alarming situation is when you wake up in the middle of the night and your arm feels completely paralyzed. The first time that this happens to you, you might actually be convinced it is. But there is no reason to panic, Tolbert says. As long as the feeling and strength to come back after a few seconds, shake out (with some help from the not-dead arm), you’re good. The longer you are lying on it, though, the longer it will take for the feeling to return.
“If you laid like that day, you’re not going to get the oxygen flowing in the blood, in addition to the fact that the nerve is compromised,” that could be problematic, Tolbert says. It is not super common, but it happens. There is a condition called Saturday Night Palsy which can happen if you have been drinking, only on your arm or hand, and of your body to sloshing wake up when it starts to stun. There is also Honeymoon Palsy, which is when your bedmate is the one sleeping on your arm the whole night. Both can lead to long-term numbness, and a few months to recover, depending on how long the nerve was compressed.
As long as the structure of the nerve is intact and the myelin layer (the protective layer of fat and protein protects the nerve) is not compromised, there shouldn’t be any permanent damage. “If, for example, you have a stab or gunshot wound, and the nerve is damaged, then it is very serious,” Tobert said. “Now you have disturbed the architecture of the nerve. But as long as the architecture is not disturbed, then it has a good prognosis.”
If you have ever experienced numbness or tingling and it does not resolve after a few minutes, or if it happens randomly, contact your doctor. If it happens in the thumb, index, middle, and lower half of the ring finger, the carpal tunnel syndrome. Certain diseases, such as diabetes or a vitamin B12 deficiency, they may be more susceptible to nerve problems, and should be addressed to prevent permanent damage.