Speaker 1: Welcome to Brainstuff from house stuff works dot com where
Speaker 1: smart happens. Hi. I'm Marcial Brain with today's question. What
Speaker 1: makes your arms, legs and feet fall asleep? This is
Speaker 1: definitely a strange sensation. You get up out of your
Speaker 1: seat and all you can feel from one foot is
Speaker 1: an uncomfortable tingling. Or you wake up in the middle
Speaker 1: of the night and you can't even move your arm
Speaker 1: at all, and then as your body part wakes up,
Speaker 1: this strange tingling intensifies just what is going on here.
Speaker 1: Usually you feel this familiar sensation after you've been putting
Speaker 1: pressure on part of your body, sitting on a foot,
Speaker 1: sleeping on an arm, or something like that. When you
Speaker 1: apply this pressure for a prolonged period of time, you
Speaker 1: actually cut off communication from your brain to parts of
Speaker 1: your body. The pressure squeezes nerve pathways so that the
Speaker 1: nerves can't transmit a electrochemical impulses properly. Nerve impulses carry
Speaker 1: sensation information from nerve endings in the body to the brain,
Speaker 1: as well as instructions from the brain to the parts
Speaker 1: of the body. When you interfere with this transfer by
Speaker 1: squeezing the nerve pathways, you don't have full feeling in
Speaker 1: that body part, and your brain has trouble telling that
Speaker 1: body part what to do. This pressure can also squeeze arteries,
Speaker 1: stopping them from carrying nutrients to body cells. Without these nutrients,
Speaker 1: the nerve cells may behave abnormally, which can further interfere
Speaker 1: with communicating bodily sensations. Due to both of these factors,
Speaker 1: the information transmitted from the body part becomes somewhat jumbled
Speaker 1: and the brain receives strange messages. Some nerve cells don't
Speaker 1: transmit any information at all, and others start sending impulses erratically.
Speaker 1: This causes you to feel a strange tingling sensation. Once
Speaker 1: you do move your foot, stretch your legs, or roll
Speaker 1: over off your arm, the nerve of impulses begin to
Speaker 1: flow properly again. You don't regain feeling right away, However,
Speaker 1: there is a certain amount of readjustment time before the
Speaker 1: nerves transmit impulses correctly. This increases the intensity of the tingling,
Speaker 1: causing the familiar pins and needles sensation. If this has
Speaker 1: ever happened to you, you know that there are actually
Speaker 1: a few distinct sensations you go through as your body
Speaker 1: part wakes up. The tingling may be followed by a
Speaker 1: more uncomfortable burning sensation before your body part finally returns
Speaker 1: to normal. This happens because the nerves in your body
Speaker 1: are made up of separate long nerve cells that carry
Speaker 1: different sorts of impulses. These nerve fibers have different surrounding structures.
Speaker 1: Some nerve fibers have thicker insulation around them, and so
Speaker 1: they take longer to begin transmitting impulses properly after they've
Speaker 1: been squeezed. The fibers that transmit pain and temperature information
Speaker 1: are relatively thin, so you feel the tingling sensations pretty quickly.
Speaker 1: Motor control fibers are thinner than the ones carrying touch information,
Speaker 1: so you can move the body part before you've regained
Speaker 1: complete feeling in it. Eventually, all your nerve fibers return
Speaker 1: to normal, and you regain full use of your sleeping
Speaker 1: body part. For more on this and thousands of other topics,
Speaker 1: is it how staff works dot com