Why do pins and needles happen?

You’ve been sitting with your legs crossed for too long and hit your elbow on something hard. Welcome to Pins and Needles City, where you are the only resident. But what causes that strange feeling of tingling and numbness happening at the same time? Most of us think it’s a lack of blood flow to the area because pins and needles usually happen when we put pressure on a body part and don’t move it for a long time. However, as the latest episode of SciShow shows, blood flow is only half of the story.

Pins and needles, also called paraesthesia, happens when you cut off the blood supply to your sensory nerves. This means that they can’t get the oxygen and energy they need to keep sending signals to your brain about what you’re touching. This will make you feel numb, and the feeling won’t go away until you uncross your legs or start moving around again. The fun part comes next: the horrible, overwhelming tingling.

The pins-and-needles feeling happens when your nerves are suddenly given access to blood again. This causes them to misfire as they start up again, which your brain interprets as pins-and-needles.

You can also get pins and needles by putting pressure on a nerve, which also stops blood from getting to the tissues around it. A classic example is when you hit your funny bone and make yourself miserable for the next minute. Hank Green says in the video above that this feeling is caused by your elbow because it’s connected to the ulnar nerve, which runs from your neck to your hands and is especially exposed and vulnerable in the elbow area.

But having pins and needles isn’t that bad because it only lasts a minute or two, right? Well, if you’re really unlucky, that tingling feeling can last for days. DAYS. And the same thing can happen if a nerve is severely damaged, if a tumor presses on nerves, or if a person has a disorder of the nervous system like multiple sclerosis.

How do you get rid of pins and needles? I’ll let Hank tell you that little secret in the SciShow episode above, but let’s just say that until it’s all over, you’re going to have to be okay with looking like a fool. But, hey, it’s worth it if I don’t tingle anymore, right?