If you've ever woken up in the night with a dead arm then you'll know what an unpleasant and sometimes alarming experience it can be. You wake up to find that you have absolutely no sensation and no movement in that limb and the only way you can move it is to pick it up with the other arm. While arms are commonly the victims of this effect though, it can also impact affect our legs, our torsos, our hands and really nothing is safe from the occasional 'sleep'.
Most of us remember the first time a limb fell asleep as a scary moment. If you've never experienced the sensation before it can understandably give you cause for concern as you worry that you may have permanently damaged it.
Not to fear though – a limb falling asleep is usually harmless, and once you know what's going on it all makes a little more sense.
Why Our Limbs Fall Asleep
The common misconception with limbs falling asleep is that it's due to the blood circulation being cut off. If this were actually true though, then it really would be a cause for concern as a complete lack of blood would result in serious damage.
What's happening instead, is that the application of pressure is causing the nerve cells to become starved of nutrients. This then results in a variety of strange effects – preventing normal communication between the brain and the limb and also resulting in the random firing of those nerves which causes the 'pins and needles' feeling that is technically known as 'parasthesia'. This is also what happens when you hit your funny bone or your 'ulnar nerve' located on your elbow.
Is it a Problem?
One of the reasons that our nerves respond in this way is that it has survival value in that it warns us that we're causing damage and should move. While a case of dead arm or pins and needles is nothing to worry about in the short term, if it goes on for a prolonged period the nerves can stop transmitting feeling altogether.
So there you have it, a dead arm is a result of squeezing your nerves and starving them of nutrients. It's no big deal, but it's still a good idea to stop once you notice that tingling feeling.