1
00:00:00,520 --> 00:00:03,840
Speaker 1: Welcome to Brainstuff from house stuff works dot com where

2
00:00:03,840 --> 00:00:15,120
Speaker 1: smart happens. Hi. I'm Marcial Brain with today's question. What

3
00:00:15,360 --> 00:00:19,639
Speaker 1: makes your arms, legs and feet fall asleep? This is

4
00:00:19,720 --> 00:00:22,720
Speaker 1: definitely a strange sensation. You get up out of your

5
00:00:22,760 --> 00:00:25,160
Speaker 1: seat and all you can feel from one foot is

6
00:00:25,200 --> 00:00:28,280
Speaker 1: an uncomfortable tingling. Or you wake up in the middle

7
00:00:28,320 --> 00:00:30,560
Speaker 1: of the night and you can't even move your arm

8
00:00:30,600 --> 00:00:33,479
Speaker 1: at all, and then as your body part wakes up,

9
00:00:33,560 --> 00:00:38,160
Speaker 1: this strange tingling intensifies just what is going on here.

10
00:00:38,920 --> 00:00:42,360
Speaker 1: Usually you feel this familiar sensation after you've been putting

11
00:00:42,400 --> 00:00:45,080
Speaker 1: pressure on part of your body, sitting on a foot,

12
00:00:45,159 --> 00:00:47,960
Speaker 1: sleeping on an arm, or something like that. When you

13
00:00:48,000 --> 00:00:51,400
Speaker 1: apply this pressure for a prolonged period of time, you

14
00:00:51,479 --> 00:00:54,680
Speaker 1: actually cut off communication from your brain to parts of

15
00:00:54,800 --> 00:00:58,600
Speaker 1: your body. The pressure squeezes nerve pathways so that the

16
00:00:58,680 --> 00:01:03,880
Speaker 1: nerves can't transmit a electrochemical impulses properly. Nerve impulses carry

17
00:01:03,920 --> 00:01:07,440
Speaker 1: sensation information from nerve endings in the body to the brain,

18
00:01:07,840 --> 00:01:10,520
Speaker 1: as well as instructions from the brain to the parts

19
00:01:10,520 --> 00:01:13,720
Speaker 1: of the body. When you interfere with this transfer by

20
00:01:13,840 --> 00:01:17,200
Speaker 1: squeezing the nerve pathways, you don't have full feeling in

21
00:01:17,240 --> 00:01:20,479
Speaker 1: that body part, and your brain has trouble telling that

22
00:01:20,560 --> 00:01:24,760
Speaker 1: body part what to do. This pressure can also squeeze arteries,

23
00:01:24,800 --> 00:01:29,240
Speaker 1: stopping them from carrying nutrients to body cells. Without these nutrients,

24
00:01:29,280 --> 00:01:33,080
Speaker 1: the nerve cells may behave abnormally, which can further interfere

25
00:01:33,080 --> 00:01:37,640
Speaker 1: with communicating bodily sensations. Due to both of these factors,

26
00:01:37,840 --> 00:01:42,319
Speaker 1: the information transmitted from the body part becomes somewhat jumbled

27
00:01:42,640 --> 00:01:46,760
Speaker 1: and the brain receives strange messages. Some nerve cells don't

28
00:01:46,800 --> 00:01:51,000
Speaker 1: transmit any information at all, and others start sending impulses erratically.

29
00:01:51,440 --> 00:01:55,720
Speaker 1: This causes you to feel a strange tingling sensation. Once

30
00:01:55,760 --> 00:01:58,440
Speaker 1: you do move your foot, stretch your legs, or roll

31
00:01:58,520 --> 00:02:01,280
Speaker 1: over off your arm, the nerve of impulses begin to

32
00:02:01,280 --> 00:02:05,160
Speaker 1: flow properly again. You don't regain feeling right away, However,

33
00:02:05,680 --> 00:02:08,640
Speaker 1: there is a certain amount of readjustment time before the

34
00:02:08,720 --> 00:02:14,079
Speaker 1: nerves transmit impulses correctly. This increases the intensity of the tingling,

35
00:02:14,240 --> 00:02:18,480
Speaker 1: causing the familiar pins and needles sensation. If this has

36
00:02:18,520 --> 00:02:20,920
Speaker 1: ever happened to you, you know that there are actually

37
00:02:20,960 --> 00:02:24,120
Speaker 1: a few distinct sensations you go through as your body

38
00:02:24,160 --> 00:02:27,000
Speaker 1: part wakes up. The tingling may be followed by a

39
00:02:27,080 --> 00:02:31,320
Speaker 1: more uncomfortable burning sensation before your body part finally returns

40
00:02:31,360 --> 00:02:34,760
Speaker 1: to normal. This happens because the nerves in your body

41
00:02:34,760 --> 00:02:38,360
Speaker 1: are made up of separate long nerve cells that carry

42
00:02:38,400 --> 00:02:43,760
Speaker 1: different sorts of impulses. These nerve fibers have different surrounding structures.

43
00:02:43,800 --> 00:02:47,640
Speaker 1: Some nerve fibers have thicker insulation around them, and so

44
00:02:47,680 --> 00:02:51,680
Speaker 1: they take longer to begin transmitting impulses properly after they've

45
00:02:51,680 --> 00:02:55,919
Speaker 1: been squeezed. The fibers that transmit pain and temperature information

46
00:02:56,040 --> 00:03:00,880
Speaker 1: are relatively thin, so you feel the tingling sensations pretty quickly.

47
00:03:01,360 --> 00:03:05,160
Speaker 1: Motor control fibers are thinner than the ones carrying touch information,

48
00:03:05,480 --> 00:03:08,200
Speaker 1: so you can move the body part before you've regained

49
00:03:08,240 --> 00:03:12,519
Speaker 1: complete feeling in it. Eventually, all your nerve fibers return

50
00:03:12,600 --> 00:03:15,880
Speaker 1: to normal, and you regain full use of your sleeping

51
00:03:16,000 --> 00:03:20,680
Speaker 1: body part. For more on this and thousands of other topics,

52
00:03:20,960 --> 00:03:26,320
Speaker 1: is it how staff works dot com