You know that tingly feeling you get when a foot falls asleep? It's almost like a cross between a tickle and a cramp, and it's pretty harmless, unless you're trying to stand up and fall flat on your face. We tend to reference this situation as a limb falling asleep, which definitely works to explain the feeling, but doesn't really make sense on a scientific level, since, you know, arms and legs don't have consciousness. So what does it actually mean when your arms and legs fall asleep, and why does it happen in the first place?
In general, feeling temporary tingling or numbness in any of your limbs is a totally normal thing, and nothing to be worried about. The scientific term for it is "paresthesia," and it's caused by a lack of blood flow to the affected area.
Lack of blood flow sounds pretty scary, but if it's a temporary thing (like your dog lying on your leg while you're watching a movie), then it's no big deal at all.
The tingling is often a sensory response by your nerves from being "pinched" through consistent applied pressure.
This is why you feel so funny when you finally get the blood flowing again- your nerves are responding to the newfound blood flow and reacting to the increased circulation. For anyone who's ever smacked their funny bone and burst into laughter, you know that it's a pretty similar tingly feeling to a limb falling asleep. That's because both sensations derive pressure being placed directly on your nerves.
In general, paresthesia has no long term side effects and is nothing to be stressed out about, so you can totally feel free to walk around pretending you're a zombie until the feeling comes back, at which point you can go on with your life.
Don't freak out if you don't immediately get sensation back to your afflicted body part, or if it initially feels entirely numb. The longer you've been applying pressure to the limb, the longer it'll take to get blood flow back, which is why you can sometimes wake up with an arm that feels lifeless, and wait several minutes to regain feeling in your fingers. There's no need to stress. Just make sure that you're extra careful with the limb until you get feeling back, because you could potentially hurt yourself indirectly by stumbling or dropping something.
If you're experiencing any level of chronic paresthesia, though, it could be a sign of something serious.
Chronic numbness or tingling sensations in your limbs is usually an indicator of any number of health matters, ranging from the mild to the severe. It could indicate a vitamin B deficiency, too much fluid retention, carpal tunnel syndrome, or it might even be a sign of nerve damage.
Whenever you're experiencing chronic nerve-related symptoms like limbs falling asleep, you should immediately talk to a medical professional. But again, it's beyond important to pay attention to when, and why, this might be happening.
For example, if your leg falls asleep every day because you tend to sit in a crossed-leg position at your desk, then that's not the same as feeling chronic numbness in limbs for no reason at all. The first thing that you should always consider is blood flow: Are you getting enough to the area, or are you applying pressure in some way?
If you feel numbness or tingling for long periods of time even when there's absolutely no pressure being applied to your limbs, that is when it's time to talk to someone ASAP. Otherwise, the only thing you really need to do is shake it off.