Recorded at | July 15, 2020 |
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Event | Sleeping with Science |
Duration (min:sec) | 04:47 |
Video Type | Original Content |
Words per minute | 176.69 medium |
Readability (FK) | 57.93 easy |
Speaker | Matt Walker |
Official TED page for this talk
Synopsis
Did you know you go on a journey every night after you close your eyes? Sleep scientist Matt Walker breaks down the difference between REM (Rapid-Eye Movement) and non-REM sleep, what occurs during each stage of sleep -- and why it's important to get enough of both.
1 | 00:00 | Sleep is perhaps the single most effective thing | ||
2 | 00:02 | that we can do each and every day | ||
3 | 00:05 | to reset the health of our brain and our body. | ||
4 | 00:08 | And by understanding a little bit more about what sleep is, | ||
5 | 00:12 | perhaps we can get the chance to improve both the quantity and the quality | ||
6 | 00:17 | of our sleep. | ||
7 | 00:18 | [Sleeping with Science] | ||
8 | 00:20 | (Music) | ||
9 | 00:23 | So, exactly what is sleep? | ||
10 | 00:26 | Well, sleep, at least in human beings, | ||
11 | 00:28 | is subdivided into two main types. | ||
12 | 00:31 | On the one hand, we have non-rapid eye movement sleep, | ||
13 | 00:35 | or non-REM sleep for short. | ||
14 | 00:37 | But on the other hand, | ||
15 | 00:38 | we have rapid eye movement sleep, or REM sleep. | ||
16 | 00:42 | And non-REM sleep has been further subdivided | ||
17 | 00:45 | into four separate stages, | ||
18 | 00:47 | unimaginatively called stages one through four, | ||
19 | 00:51 | increasing in their depth of sleep. | ||
20 | 00:54 | And as we go into those light stages of non-REM sleep, | ||
21 | 00:58 | your heart rate starts to decrease, | ||
22 | 01:01 | your body temperature starts to drop | ||
23 | 01:03 | and your electrical brain wave activity starts to slow down. | ||
24 | 01:07 | But as we move into deeper non-rapid eye movement sleep, | ||
25 | 01:11 | stages three and four, | ||
26 | 01:13 | now all of a sudden the brain erupts | ||
27 | 01:16 | with these huge, big, powerful brain waves. | ||
28 | 01:20 | The body is actually recharged in terms of its immune system. | ||
29 | 01:25 | We also get this beautiful overhaul of our cardiovascular system. | ||
30 | 01:30 | And, in fact, upstairs in the brain, | ||
31 | 01:32 | deep non-REM sleep will help consolidate memories | ||
32 | 01:36 | and fixate them into the neural architecture of the brain. | ||
33 | 01:39 | So that's non-REM sleep. | ||
34 | 01:42 | But let's come on to REM sleep, | ||
35 | 01:44 | which is the other main type of sleep. | ||
36 | 01:46 | And it's during REM sleep when we principally have the most vivid, | ||
37 | 01:51 | the most hallucinogenic types of dreams. | ||
38 | 01:54 | The brain wave activity actually starts to speed up again. | ||
39 | 01:58 | It's during REM sleep that we receive almost a form of emotional first aid. | ||
40 | 02:04 | And it's also during REM sleep where we get a boost for creativity, | ||
41 | 02:09 | that it stitches information together | ||
42 | 02:12 | so that we wake up with solutions | ||
43 | 02:14 | to previously difficult problems that we were facing. | ||
44 | 02:18 | Coming back to these two types of sleep, | ||
45 | 02:20 | it turns out that non-REM and REM will play out | ||
46 | 02:24 | in a battle for brain domination throughout the night, | ||
47 | 02:28 | and that cerebral war is going to be won and lost | ||
48 | 02:33 | every 90 minutes, | ||
49 | 02:34 | and then it's going to be replayed every 90 minutes. | ||
50 | 02:38 | And what this produces is a standard cycling architecture of human sleep, | ||
51 | 02:44 | a standard 90-minute cycle. | ||
52 | 02:46 | But what's different, however, | ||
53 | 02:48 | is that the ratio of non-REM to REM within those 90-minute cycles | ||
54 | 02:54 | changes as we move across the night, | ||
55 | 02:57 | such that in the first half the night, | ||
56 | 02:59 | the majority of those 90-minute cycles | ||
57 | 03:02 | are comprised of lots of deep non-REM sleep, | ||
58 | 03:06 | particularly stages three and four of non-REM sleep. | ||
59 | 03:09 | But as we push through to the second half of the night, | ||
60 | 03:13 | now that seesaw balance actually shifts over, | ||
61 | 03:17 | and instead, most of those 90-minute cycles | ||
62 | 03:20 | are comprised of a lot more rapid eye movement sleep, or dream sleep, | ||
63 | 03:25 | as well as stage-two non-REM sleep, | ||
64 | 03:28 | that lighter form of non-REM sleep. | ||
65 | 03:30 | And it turns out that there are implications | ||
66 | 03:34 | for understanding how sleep is structured in this way. | ||
67 | 03:38 | Let's take someone who typically goes to bed at 10pm, | ||
68 | 03:42 | and they wake up at 6am, | ||
69 | 03:44 | so they have an eight-hour sleep window. | ||
70 | 03:47 | But this morning, they have to wake up early | ||
71 | 03:50 | for an early morning meeting, | ||
72 | 03:52 | or they want to get a jump start on the day | ||
73 | 03:54 | to get to the gym. | ||
74 | 03:55 | And as a consequence, they have to wake up at 4am in the morning, | ||
75 | 03:59 | rather than 6am in the morning. | ||
76 | 04:02 | How much sleep have they actually lost? | ||
77 | 04:04 | Two hours out of an eight-hour night of sleep | ||
78 | 04:07 | means that they've lost 25 percent of their sleep. | ||
79 | 04:11 | Well, yes and no. | ||
80 | 04:13 | They have lost 25 percent of all of their sleep, | ||
81 | 04:17 | but because REM sleep comes mostly in the second half of the night | ||
82 | 04:21 | and particularly in those last few hours, | ||
83 | 04:23 | they may have lost perhaps 50, 60, maybe even 70 percent | ||
84 | 04:28 | of all of their REM sleep. | ||
85 | 04:30 | So there are real consequences to understanding what sleep is | ||
86 | 04:36 | and how sleep is structured. | ||
87 | 04:37 | And we'll learn all about the benefits of these different stages of sleep | ||
88 | 04:42 | and the detriments that happen when we don't get enough of them | ||
89 | 04:45 | in subsequent episodes. |