A look at the causes behind your legs, feet, hands, and arms falling asleep, and why they tingle and have pins and needles pain.
At one time or another, everyone has had the experience of having some body part falling asleep. It may happen when you wake up in the night and realize that you have been laying on one of your arms or hands while sleeping. You could have sat too long in one position on a hard surface and your leg or foot went to sleep.
Regardless of how it happened, the tingling sensation coupled with the slightly painful feeling of pins and needles make it impossible to miss the fact that you have some limb or limbs that have fallen asleep. Knowing how it happens does little to improve the understanding of why it happens.
Your body constantly talks to your brain.
Every part of your body stays in communication with your brain by way of your central nervous system. Your body parts send signals to your brain informing it of the general well being of that area of the body. As long as this communication is functioning properly, your body feels right to you.
The tingling sensation happens because of nerve issues in the affected limb.
When you have a limb fall asleep, it means that signals from that limb are no longer reaching the brain in the way your brain expects. If you sit too long on a hard surface or lay on your arm while you sleep, nerves are compressed in that area. When nerves are compressed for too long, they can be damaged. Your body reacts to this compression in a way to warn you of potential nerve problems.
Tingling and pain like pins and needles are signals that you need to give the nerve relief.
When nerves are compressed for an extended period of time, they stop being able to send the proper signal to the brain. Sometimes if the signal becomes intermittent, your brain responds by making a mild tingling sensation in the affected area.
The name for this feeling is paresthesia. If the signal stops altogether, you may just feel nothing. For severe cases of limbs falling asleep, people sometimes just feel that the limb is numb for a while before the tingling begins.
The pins and needles pain is caused by the nerve attempting to establish a correct connection with the brain.
Communication does not start up perfectly when the nerve is decompressed. The nerve will fire somewhat randomly at first. This brings the pain. Some other nerves may even join in to reinforce the signal. Until the nerve becomes synchronized with the central nervous system, the pain will continue. This is to keep you from using a limb that is not yet functioning properly. Walking on a leg or foot that is asleep is a fall risk. Trying to use a hand that is asleep can get it injured.
Blood flow has to be restored before the nerve can function at its best.
The same conditions that compress the nerve act as a tourniquet to blood vessels in the area. Without a good supply of blood delivering oxygen, the nerve can have problems generating the right type of signal for the brain. This can delay the restoring of communication and prolong the discomfort until circulation is normal for the nerves in the area.