"Listen to your body" has become something of a meaningless mantra. But when it comes to that tingling-meets-numb sensation that happens after falling asleep on your forearm or sitting cross-legged for too long, your body knows what it wants—and it wants to move. Pins and needles, or what science calls temporary paresthesia, occurs when some sort of exterior pressure hits your body with a one-two punch, compressing the nerve and cutting off localized blood flow, which messes with their ability to send signals to the brain, says Naomi Feuer, M.D., an assistant professor of neurology, neuroscience, and neuromuscular disease at Weill Cornell Medical College.
Your legs can fall asleep in all sorts of situations, but there's something particularly undignified about it happening on the john—probably after spending too much time scrolling through Instagram. As it happens, your nerves are caught between a rock and a hard place. “You have the toilet seat right up against your leg, and it can really put pressure on the blood vessels," Feuer says. It turns out bodies aren’t made to be squeezed against a hard surface for a prolonged period of time. With those tiny blood vessels impaired, your nerves sense something's not right; they send the tingling sensation as a pain response, which is supposed to tell you to move. Fine, body. We get it.
Your leg (or arm or foot) keeps hurting even after adjusting your position because the nerves have already raised the alarm, and until they get back to their normal state, you’ll feel a cascade of sensations, Feuer says. That could be everything from feeling hot to cold to numb—basically a Katy Perry song of pain.
Is There No Escape?
There’s no hard-and-fast rule for how quickly your leg (or any other extremity) will fall asleep, so keep an eye on when it tends to hit, and go from there, says Stephen Kamin, M.D., an associate professor of neurology at Rutgers New Jersey Medical School. If you notice you always feel an ominous tingle ten minutes into Netflix and chill, start massaging your legs just before that, Feuer advises. It’ll help bring blood to the area, and stretching and shifting positions is also always a good idea. According to Feuer, people with poor circulation are more prone to having their legs fall asleep, so if you’ve always got cold hands or bring a sweater everywhere, you may want to avoid sitting cross-legged.
In general, temporary paresthesia is usually nothing to worry about. (In rare cases, seemingly endless pins and needles could be a sign of chronic paresthesia, which often requires medical attention.) But if you feel your legs going numb and decide to throw caution to the wind and not adjust your position, just know what you’re signing up for: The longer the compression, the more likely you'll go from a few seconds of tingling to minutes of feeling like you're dragging along a limp, lifeless limb, Kamin says. Extreme scenario, though—otherwise, a few minutes of Stomp the Yard, bathroom edition should wake the nerves up again.