Give Now

A Moment of Science

When Your Arm Falls Off

Why do arms sometimes fall asleep and why do they start to tingle?

A man's veiny arm

Photo: davco9200 (Flickr)

Nerves allow you to sense feeling by delivering messages to the brain, therefore describing sensory input.

If you put extended pressure on your arm, by leaning or sleeping on it, it might go numb and then give you a tingling feeling. Your arm falls asleep like this because prolonged pressure on a nerve, or on a nerve’s blood supply, can temporarily damage it.

Sensory Input

Nerves allow you to sense feeling by sending messages to the brain describing sensory input. If you touch a hot burner, you pull your hand back because the nerves in your hand have sent the message to your brain that your hand is in pain.

When a nerve is compressed or when the blood supply to a nerve is compromised, the normal messages nerves send to the brain are stopped or altered. At this point, when the nerve is no longer functioning appropriately, numbness occurs.

Nerve Recovery

When the nerve begins to recover, you may feel a tingling sensation. This feeling of pins and needles is due to the fact that at the early stages of the nerves’ recovery, it functions inappropriately, giving your brain misinformation.

To understand why nerves work this way, we need to think about the anatomy of a nerve. Every nerve is filled with thousands of nerve fibers, each carrying specific information to the brain.

False Signals

Some of these fibers are large, others are small, and all recover at different rates. Because the thousands of fibers that make up a damaged nerve recover at different speeds, the message they collectively send the brain as they are recovering is inaccurate.

So though your arm isn’t actually tingling at all, the way it would if you received a mild electric shock, your brain believes that it’s tingling because the brain always believes messages that nerves send–whether those messages are accurate or not.

  • http://profiles.yahoo.com/u/LUNNKMP6WW3K2MJ4ZYJUHTQU2Y athikities supabiola

    If you feel abnormal at your foots,don't ignore it.You have to learn for amall fiber neuropathy at http://www.small-fiber-neuropathy.com/

Stay Connected

What is RSS? RSS makes it possible to subscribe to a website's updates instead of visiting it by delivering new posts to your RSS reader automatically. Choose to receive some or all of the updates from A Moment of Science:

Support for Indiana Public Media Comes From

About A Moment of Science

Search A Moment of Science