Pins and needles

April 28th, 2026

Written by Lindsay Ejoh

Imagine you’re at the movies with the potential love of your life by your side. You’re so excited that you put your arm around them. Time is passing…things are going well until you realize your arm has started to feel strangely numb and tingly. You don’t want to awkwardly pull away, but at the same time, your nerves are telling you, “MOVE YOUR ARM!” Have you ever wondered why this happens? 

This numb, tingly, “pins and needles” feeling is called paresthesia¹, and occurs when you put pressure on your nerves or blood vessels. Let’s explore why nerves and blood vessels act like this when under pressure. 

Nerves under pressure

Nerves are like electrical wires that send signals between your body and your brain. When you touch your date, the nerves in your arm communicate to your brain about the position of your arm, how warm they feel, the feel of the couch behind them, etc. 

Let’s zoom into the cellular level to understand how they do this. Nerves are bathed in a fluid that contains electrically charged molecules called ions. Some of these ions have a positive charge, and others have a negative charge. Nerve cells become electrically active when  positively charged ions enter the cell. In this electrically active state, they can “fire” signals³ that allow them to communicate information about the temperature of your date and positioning of your arm to the brain.

When you put sustained pressure on a nerve, like your crush’s shoulder pressing on the nerve in your arm, or the awkward angle your arm has to sit at to maintain your position, this pressure disrupts the crucial flow of positive and negative ions between the inside and outside of the cell⁴. This in turn disrupts the ability for nerves to fire adequately, blocking messages like “I feel touch” or “my arm is placed in this position” from being sent properly, which causes the numb feeling in your arm. 

Blood vessels under pressure

Your crush’s shoulder is not only compressing the nerve in your arm, but also applying pressure on your blood vessels which limits blood flow. Think of your vessels like a water hose. Pressing down on a hose will limit the amount of water that can get through. Similarly, when under pressure, blood vessels can’t get enough blood to the body. One of the main jobs of your blood is to carry oxygen and glucose to different parts of the body including your nerves. The purpose of oxygen and glucose is to help nerve cells create a molecule called ATP, adenosine triphosphate, which is an “energy” molecule used to power them. So without enough blood, nerves cannot generate the energy they rely on for the electrical power to send enough touch signals to the brain, which as described earlier, results in that numb feeling in your limb. 

Shifting positions

When you finally remove pressure, perhaps by awkwardly switching to holding hands with your date, blood rushes back to the nerves, allowing the nerves to “wake up” and fire signals again. However, they fire rapidly and irregularly. Think of it like turning a sound system on and getting a loud burst of chaotic sound before things stabilize. When your brain receives these sudden, disorganized waves of signals from the newly decompressed nerves, scientists suspect that it doesn’t know how to make sense of them, resulting in the sensation of pins and needles on the skin. To prove this, scientists could measure brain activity after one shifts from an awkward position and compare that to how the brain would respond to tiny, light-pressure pins being applied across the arm- to see if the disorganized wave of signals is the same in both situations. 

Regardless, most of the time, this entire process is harmless, simply a signal from your nervous system to alert you to change position to prevent further damage that can result from prolonged blockage of blood flow. However, if you ever experience numbness that sticks around, happens without pressure, or comes with weakness or pain, it may be worth getting checked out by a doctor². Temporary paresthesia (lasting from a few minutes to a couple days) is harmless and common. Persistent paresthesia (lasting more than a few days) is a signal worth listening to. 

References 

1. Cleveland Clinic. (2023, April 26). Paresthesia: What it is, causes, symptoms & treatment. https://my.clevelandclinic.org/health/symptoms/24932-paresthesia
2. Healthdirect Australia. (n.d.). Limb numbness. https://www.healthdirect.gov.au/limb-numbness
3. Teach Me Physiology (2024, September 23). Action Potential. https://teachmephysiology.com/nervous-system/synapses/action-potential/
4. The Scientist. (2024). What causes the pins and needles sensation? https://www.the-scientist.com/what-causes-the-pins-and-needles-sensation-73518

Cover image sourced from Pexels user Kindel Media