WEBVTT - What makes your arms, legs and feet fall asleep?

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<v Speaker 1>Welcome to Brainstuff from house stuff works dot com where

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<v Speaker 1>smart happens. Hi. I'm Marcial Brain with today's question. What

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<v Speaker 1>makes your arms, legs and feet fall asleep? This is

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<v Speaker 1>definitely a strange sensation. You get up out of your

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<v Speaker 1>seat and all you can feel from one foot is

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<v Speaker 1>an uncomfortable tingling. Or you wake up in the middle

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<v Speaker 1>of the night and you can't even move your arm

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<v Speaker 1>at all, and then as your body part wakes up,

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<v Speaker 1>this strange tingling intensifies just what is going on here.

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<v Speaker 1>Usually you feel this familiar sensation after you've been putting

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<v Speaker 1>pressure on part of your body, sitting on a foot,

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<v Speaker 1>sleeping on an arm, or something like that. When you

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<v Speaker 1>apply this pressure for a prolonged period of time, you

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<v Speaker 1>actually cut off communication from your brain to parts of

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<v Speaker 1>your body. The pressure squeezes nerve pathways so that the

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<v Speaker 1>nerves can't transmit a electrochemical impulses properly. Nerve impulses carry

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<v Speaker 1>sensation information from nerve endings in the body to the brain,

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<v Speaker 1>as well as instructions from the brain to the parts

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<v Speaker 1>of the body. When you interfere with this transfer by

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<v Speaker 1>squeezing the nerve pathways, you don't have full feeling in

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<v Speaker 1>that body part, and your brain has trouble telling that

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<v Speaker 1>body part what to do. This pressure can also squeeze arteries,

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<v Speaker 1>stopping them from carrying nutrients to body cells. Without these nutrients,

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<v Speaker 1>the nerve cells may behave abnormally, which can further interfere

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<v Speaker 1>with communicating bodily sensations. Due to both of these factors,

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<v Speaker 1>the information transmitted from the body part becomes somewhat jumbled

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<v Speaker 1>and the brain receives strange messages. Some nerve cells don't

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<v Speaker 1>transmit any information at all, and others start sending impulses erratically.

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<v Speaker 1>This causes you to feel a strange tingling sensation. Once

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<v Speaker 1>you do move your foot, stretch your legs, or roll

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<v Speaker 1>over off your arm, the nerve of impulses begin to

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<v Speaker 1>flow properly again. You don't regain feeling right away, However,

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<v Speaker 1>there is a certain amount of readjustment time before the

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<v Speaker 1>nerves transmit impulses correctly. This increases the intensity of the tingling,

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<v Speaker 1>causing the familiar pins and needles sensation. If this has

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<v Speaker 1>ever happened to you, you know that there are actually

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<v Speaker 1>a few distinct sensations you go through as your body

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<v Speaker 1>part wakes up. The tingling may be followed by a

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<v Speaker 1>more uncomfortable burning sensation before your body part finally returns

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<v Speaker 1>to normal. This happens because the nerves in your body

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<v Speaker 1>are made up of separate long nerve cells that carry

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<v Speaker 1>different sorts of impulses. These nerve fibers have different surrounding structures.

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<v Speaker 1>Some nerve fibers have thicker insulation around them, and so

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<v Speaker 1>they take longer to begin transmitting impulses properly after they've

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<v Speaker 1>been squeezed. The fibers that transmit pain and temperature information

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<v Speaker 1>are relatively thin, so you feel the tingling sensations pretty quickly.

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<v Speaker 1>Motor control fibers are thinner than the ones carrying touch information,

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<v Speaker 1>so you can move the body part before you've regained

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<v Speaker 1>complete feeling in it. Eventually, all your nerve fibers return

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<v Speaker 1>to normal, and you regain full use of your sleeping

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<v Speaker 1>body part. For more on this and thousands of other topics,

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<v Speaker 1>is it how staff works dot com