Curious Kids is a series for kids of all ages. If you have a question you’d like an expert to answer, send it to [email protected]
What happens when your foot falls asleep? – Helen E., age 8, Somerville, Massachusetts
Imagine that you have just sat down to watch your favorite TV show. You decide to sleep with your legs slanted because you find it more comfortable that way.
When the episode ends, you try to stand up and suddenly your right leg is not working. At first you can’t move it, then it feels like there are pins and needles all around. It feels uncomfortable and awkward for a minute or two, but soon you can stand up and walk normally.
What just happened?
I am an exercise physiologist – a scientist who studies what happens to our bodies when we walk and exercise. The goal of most of my research has been to understand how the brain talks to and controls the different parts of our bodies. When your foot falls asleep, something goes wrong with the communication between your brain and the muscles in that area.
Every time you decide to move your body, whether it’s standing, walking or playing a sport, your brain sends signals to your muscles to make sure they move correctly. When the brain is unable to talk with muscles or muscle groups, some strange things can happen – including a strange sleepy feeling in that part of your body.
It usually begins with a feeling of numbness or tingling in that area. This sensation, which people often refer to as “pins and needles”, is technically known as paresthesia.
Some people mistakenly think that the lack of blood flow causes this feeling. They imagine that feeling of “sleep” occurs when your blood, which carries nutrients throughout your body, cannot reach your leg. But it is not correct.
When your leg falls asleep, it’s actually because the nerves connecting the brain to the leg are constricting, depending on the position you’re sitting in. Remember, these are the nerves that carry messages back and forth between your brain and your leg to communicate. With each other. If the nerves have been compressed for a while, you won’t feel much in your leg because it can’t travel through your brain to see how it feels or whether it’s moving.
Once you start moving again, the pressure on the nerves is relieved. They “wake up” and you will start to feel the “pins and needles”. Don’t worry, this feeling will only last for a few minutes and then everything will be back to normal.
Now comes the important question: is it dangerous? Most of the time, when your leg or any other part of the body falls asleep, it is temporary and nothing to worry about. In fact, since it only lasts a minute or two, you might not even remember it happened until the end of the day.
Even if it isn’t causing any permanent damage, you’ll want to avoid the uncomfortable feeling that comes with your feet falling asleep. Here are some tips that may help:
- Change your position often.
- Don’t cross your legs for too long.
- When you have been sitting for a long time, try to stand up frequently.
You can probably never 100% stop your leg from falling asleep. So don’t worry when it happens every once in a while. It will go away very quickly – and perhaps it can remind you of those all-important brain messages your nerves are usually transmitting without you noticing.
Hello curious kids! Do you have a question that you would like an expert to answer? Ask an adult to send your question to [email protected] Please tell us your name, age and city where you live.
And since Curiosity has no age limit – adults, let us know what you’re thinking, too. We won’t be able to answer every question, but we will do our best.