The benefits of a good night's sleep - Shai Marcu — Transcript

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1. 0:07It's 4 a.m., and the big test is in eight hours,
2. 0:13followed by a piano recital.
3. 0:16You've been studying and playing for days, but you still don't feel ready for either.
4. 0:21So, what can you do?
5. 0:23Well, you can drink another cup of coffee
6. 0:25and spend the next few hours cramming and practicing,
7. 0:28but believe it or not,
8. 0:30you might be better off closing the books, putting away the music,
9. 0:33and going to sleep.
10. 0:35Sleep occupies nearly a third of our lives,
11. 0:38but many of us give surprisingly little attention and care to it.
12. 0:43This neglect is often the result of a major misunderstanding.
13. 0:46Sleep isn't lost time,
14. 0:48or just a way to rest when all our important work is done.
15. 0:52Instead, it's a critical function,
16. 0:54during which your body balances and regulates its vital systems,
17. 0:58affecting respiration
18. 1:00and regulating everything from circulation to growth and immune response.
19. 1:05That's great, but you can worry about all those things after this test, right?
20. 1:10Well, not so fast.
21. 1:12It turns out that sleep is also crucial for your brain,
22. 1:15with a fifth of your body's circulatory blood
23. 1:18being channeled to it as you drift off.
24. 1:20And what goes on in your brain while you sleep
25. 1:23is an intensely active period of restructuring
26. 1:26that's crucial for how our memory works.
27. 1:29At first glance,
28. 1:30our ability to remember things doesn't seem very impressive at all.
29. 1:3419th century psychologist Herman Ebbinghaus
30. 1:37demonstrated that we normally forget 40% of new material
31. 1:40within the first twenty minutes,
32. 1:43a phenomenon known as the forgetting curve.
33. 1:47But this loss can be prevented through memory consolidation,
34. 1:50the process by which information is moved
35. 1:53from our fleeting short-term memory to our more durable long-term memory.
36. 1:58This consolidation occurs with the help of a major part of the brain,
37. 2:02known as the hippocampus.
38. 2:05Its role in long-term memory formation
39. 2:07was demonstrated in the 1950s by Brenda Milner
40. 2:11in her research with a patient known as H.M.
41. 2:14After having his hippocampus removed,
42. 2:16H.M.'s ability to form new short-term memories was damaged,
43. 2:21but he was able to learn physical tasks through repetition.
44. 2:25Due to the removal of his hippocampus,
45. 2:27H.M.'s ability to form long-term memories was also damaged.
46. 2:32What this case revealed, among other things,
47. 2:34was that the hippocampus was specifically involved
48. 2:37in the consolidation of long-term declarative memory,
49. 2:42such as the facts and concepts you need to remember for that test,
50. 2:45rather than procedural memory,
51. 2:47such as the finger movements you need to master for that recital.
52. 2:51Milner's findings, along with work by Eric Kandel in the 90's,
53. 2:55have given us our current model of how this consolidation process works.
54. 3:00Sensory data is initially transcribed
55. 3:02and temporarily recorded in the neurons as short-term memory.
56. 3:07From there, it travels to the hippocampus,
57. 3:09which strengthens and enhances the neurons in that cortical area.
58. 3:13Thanks to the phenomenon of neuroplasticity,
59. 3:15new synaptic buds are formed, allowing new connections between neurons,
60. 3:20and strengthening the neural network
61. 3:22where the information will be returned as long-term memory.
62. 3:25So why do we remember some things and not others?
63. 3:28Well, there are a few ways to influence
64. 3:30the extent and effectiveness of memory retention.
65. 3:34For example, memories that are formed in times of heightened feeling,
66. 3:38or even stress,
67. 3:39will be better recorded due to the hippocampus' link with emotion.
68. 3:44But one of the major factors contributing to memory consolidation is,
69. 3:48you guessed it,
70. 3:49a good night's sleep.
71. 3:51Sleep is composed of four stages,
72. 3:54the deepest of which are known as slow-wave sleep
73. 3:56and rapid eye movement.
74. 3:59EEG machines monitoring people during these stages
75. 4:02have shown electrical impulses
76. 4:04moving between the brainstem, hippocampus, thalamus, and cortex,
77. 4:09which serve as relay stations of memory formation.
78. 4:13And the different stages of sleep have been shown to help consolidate
79. 4:16different types of memories.
80. 4:19During the non-REM slow-wave sleep,
81. 4:22declarative memory is encoded into a temporary store
82. 4:26in the anterior part of the hippocampus.
83. 4:28Through a continuing dialogue between the cortex and hippocampus,
84. 4:32it is then repeatedly reactivated,
85. 4:35driving its gradual redistribution to long-term storage in the cortex.
86. 4:41REM sleep, on the other hand, with its similarity to waking brain activity,
87. 4:44is associated with the consolidation of procedural memory.
88. 4:48So based on the studies,
89. 4:50going to sleep three hours after memorizing your formulas
90. 4:53and one hour after practicing your scales would be the most ideal.
91. 4:58So hopefully you can see now that skimping on sleep
92. 5:01not only harms your long-term health,
93. 5:03but actually makes it less likely
94. 5:05that you'll retain all that knowledge and practice from the previous night,
95. 5:09all of which just goes to affirm the wisdom of the phrase, "Sleep on it."
96. 5:13When you think about all the internal restructuring
97. 5:15and forming of new connections that occurs while you slumber,
98. 5:19you could even say that proper sleep
99. 5:21will have you waking up every morning with a new and improved brain,
100. 5:25ready to face the challenges ahead.