Limbs fall asleep
Published: February 12, 2024
Ever had an appendage go numb and lifeless while napping, sitting or standing?
Shoot, we’ve all experienced this “falling asleep” phenomenon countless times throughout our lives.
Matter of fact it’s such a common event that we rarely give it a second thought.
Yet despite the lion’s share of these falling asleep incidents being quite benign, there actually are instances where they should be taken seriously.
So let’s take a look at both sides of this rather bizarre occurrence, the benign side, which is as ordinary as the hiccup, and the serious side, which can sometimes be an indication of something a bit more insidious taking place.
First of all, this weird feeling we all get when an appendage falls asleep is termed paresthesia, and one of the Cleveland Clinic’s many .org websites defines paresthesia as, “the technical term for the sensation of tingling, burning, pricking or prickling, skin-crawling, itching, “pins and needles” or numbness on or just underneath your skin. It can affect places on and throughout your body and happens without an outside cause or warning.”
The most common rational offered up for this strange sensation centers on a lack of blood flow to the affected area, but typically this is not the primary reason. In most cases this phenomenon centers far more on brain-to-muscle communication than it does on blood flow.
Yup, medical science says that these situations are largely a result of the brain and muscles loosing their ability to communicate with one another.
A great example of one such situation is when we put an appendage in a compressed pose for an indeterminate amount of time - such as when sleeping or napping with one’s head resting on an arm.
Compress those arm nerves for a while and communication between the brain and arm muscles can be temporarily lost. That’s when the arm falls asleep.
Later when you wake up, take pressure off the arm and shake it out, that arm starts for feel normal again with brain-to-arm communication being restored.
What’s more, this type of paresthesia can also occur when a body part experiences a hard bump or impact, say for instance like bumping an elbow against a solid object.
Such a bump can cause an explosive tingling pain in the ulnar nerve hitting that proverbial “funny bone.”
So those two benign and ephemeral examples of paresthesia fall into a variety of paresthesia called transient paresthesia, which also includes paresthesias caused by dehydration, hyperventilation, migraines, carpal tunnel, panic attacks, seizures and whiplash.
Most of the time such transient paresthesia episodes are short-term and nothing to fret about.
But far less frequently there’s paresthesia events that have to be taken far more seriously because they’re not benign nor are they ephemeral.
These paresthesia events fall into a variety of paresthesia termed persistent paresthesia, which is composed of several sub categories.
Circulatory induced paresthesia involves poor circulation. That poor circulation disrupts nerve signals to and from the brain. One such example is Thorasic Outlet Syndrome, a circulatory condition that if chronic can result in Reynaud’s Syndrome.
This sub category can involve brain, spinal cord and/or any of the body’s nerves. Examples include brain tumors/bleeds, concussions/TBIs (traumatic brain injuries), along with herniated disks, nerve damage from frostbite, neuropathies, pinched nerves, spinal stenosis and strokes.
Metabolic and endocrine
This wide ranging sub category can be the result of vitamin deficiencies along with metabolic issues like diabetes.
Infectious diseases can cause persistent paresthesia when they affect nerves or parts of your brain. Examples of this include autoimmune and inflammatory maladies.
The nervous system is vulnerable to persistent paresthesia due to toxins like arsenic, carbon monoxide, lead and mercury. Toxins from snakes, spiders and scorpions can also cause persistent paresthesia.
As you can see there’s a wide range of causalities for persistent paresthesia, so if that falling asleep phenomenon you’re experiencing turns into a persistent and/or unabating issue that lasts for 30 minutes or more then you should seek the consultation of a healthcare provider.
Yet with this being said, know that transient paresthesia is by far the most common variety of paresthesia.
So when a limb does fall asleep know that it’s likely a temporary communication issue between your brain and muscles, and you probably need only to relieve pressure on that limb to get everybody talking again.