What’s Actually Happening When Your Arms ‘Fall off to Sleep’?

Do you often wake up in the middle of the night to a numb arm? Here’s what’s going on inside your body.

A slumbering arm, a dormant foot, apparently your body doesn’t always wake up at the same time as your brain – can this be dangerous? (Photo: iStock altered by The Quint)

You’re awake at the middle of the night but the hand under your pillow is not. Or you sit for too long on your office chair but as you get up to move, nothing...

Complete dead...ness!

A dead limb, you no longer have control over, is a weird experience. My mom often recalls my drama after the first time I had this at the age of 9 or 10. I freaked out the next morning assuming something has happened and I’ll never be able to move my hands! But here I am, writing this story with hands and fingers. All intact.

Apparently, dead arms, hands, fingers is a pretty common phenomenon. Medically it goes by the name, paresthesia, or temporary paralysis. But don’t freak out, it’s a very cool example of how the body protects itself during the paralysis of sleep.

Three Reasons Why Limbs 'Fall Asleep'

(Photo courtesy: Tumblr/Imgur)

In colloquial terms when we’re stuck in one position for too long and an arm or leg goes numb, we say, ‘it’s fallen off to sleep.’

Common myth is that ‘pins and needles sensation’ or dead limbs are caused by lack of blood flow to the nerves, if that was the case then your limbs would turn blue. In reality, it is nerve compression, the nerves are getting smashed and squashed.

And this could happen because of three main reasons:

1) Your Cells Freak Out From the Pressure

(Photo courtesy: Tumblr/ jmckeehen)

‘Move arm’, ‘lift leg’ – your brain does all the communication through the rest of your body via sensory nerve receptors. Now these neural pathways also carry the information back upstairs to the brain, that’s how you know how something feels, tastes, or smells.

While snoozing or staying in one position for too long, extreme amount of pressure can pinch the neural pathways, blocking the nutrient supply (and NOT the blood) to reach the nerve receptors. This drought makes your nerve cells get all weird. The transmitters might stop sending signals entirely, become erratic or just be all over the place.

The cacophony results in you experiencing a range of sensations within seconds – warm, prickly, numb, dead. (Photo courtesy: Tumblr/UCLA)

At this point, the brain stirs you awake, so you re-position yourself before tissue death can happen. At this point that you have an extended period of tingling sensation, it’s the nerve fibers starting to fire up again.

Also Read: Broken Sleep Is Worse Than No Sleep

2) You Wake up in the Middle of REM Sleep

Like most automated process in the human body, parenthesis is designed to keep us safe and sound. (Photo courtesy: Tumblr/TBDMovie)

During REM (rapid eye movement) sleep, where most of the recalled dreams occur – your eyes are darting but the brain signals the rest of the body into temporary paralysis so that you don’t start acting out your dreams.

A 2011 study on 36,000 volunteers found that in nearly 10% of the general population, a-third of people suffering from mental health disorders like depression, wake up during the REM phase.

As a result, temporarily stuck somewhere between dreaming and wakefulness, people momentarily experience the most bizarre sensations like heaviness on the chest, parched lungs and throat and even hallucinate. This is called sleep paralysis and can be pretty darn frightening.

3) Vitamin B Deficiency

Because behind everything totally random, there is (almost) always a deficiency. Seriously. (Photo: iStock altered by The Quint)

Frequent ‘pins and needles sensation’ or numbness is often a sign that you’re not getting your palak and fish dose. Pale skin, fatigue and body pain are other symptoms of this vitamin deficiency.

Unlike the LoC, Misfiring Here Is Not a Big Deal Unless...

It goes on for days or weeks. Even if it is for a few seconds at one go. Not that your arm will fall off but with prolonged pressure the nerves could stop feeling sensation all together. So see a doctor and find out exactly why is the repeated compression happening.

There is also a genetic neurological ailment, HNPP, where unknowingly people are prone to nerve compression in the night. This bunch of people needs to be extra mindful of their sleep position. But for the rest, it’s just really napping on the job. Chill.

Also Read: The Science Of Dreams - Why Do We Dream?