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← Hacking your memory -- with sleep

We've all been told to get a good night's sleep before a test -- finally, here's the reason why. Sleep scientist Matt Walker explains how getting enough sleep affects how our brains store and process memories.

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Showing Revision 5 created 08/11/2020 by Erin Gregory.

  1. Whether you're cramming for an exam
  2. or trying to learn
    a new musical instrument
  3. or even trying to perfect a new sport,
  4. sleep may actually be
    your secret memory weapon.
  5. [Sleeping with Science]

  6. Studies have actually told us
    that sleep is critical for memory

  7. in at least three different ways.
  8. First, we know that you need
    sleep before learning
  9. to actually get your brain ready,
  10. almost like a dry sponge,
  11. ready to initially soak up
    new information.
  12. And without sleep, the memory
    circuits within the brain
  13. effectively become
    waterlogged, as it were,
  14. and we can't absorb new information.
  15. We can't effectively lay down
    those new memory traces.
  16. But it's not only important
    that you sleep before learning,

  17. because we also know
    that you need sleep after learning
  18. to essentially hit the save button
    on those new memories
  19. so that we don't forget.
  20. In fact, sleep will actually
    future-proof that information
  21. within the brain,
  22. cementing those memories
  23. into the architecture
    of those neural networks.
  24. And we've begun to discover
  25. exactly how sleep achieves
    this memory-consolidation benefit.
  26. The first mechanism
    is a file-transfer process.

  27. And here, we can speak about
    two different structures
  28. within the brain.
  29. The first is called the hippocampus
  30. and the hippocampus
    sits on the left and the right side
  31. of your brain.
  32. And you can think of the hippocampus
  33. almost like the informational
    inbox of your brain.
  34. It's very good at receiving
    new memory files
  35. and holding onto them.
  36. The second structure
    that we can speak about

  37. is called the cortex.
  38. This wrinkled massive tissue
    that sits on top of your brain.
  39. And during deep sleep,
  40. there is this file-transfer mechanism.
  41. Think of the hippocampus like a USB stick
  42. and your cortex like the hard drive.
  43. And during the day, we're going around
  44. and we're gathering lots of files,
  45. but then during deep sleep at night,
  46. because of that limited storage capacity,
  47. we have to transfer those files
    from the hippocampus
  48. over to the hard drive
    of the brain, the cortex.
  49. And that's exactly one of the mechanisms
  50. that deep sleep seems to provide.
  51. But there's another mechanism
    that we've become aware of

  52. that helps cement
    those memories into the brain.
  53. And it's called replay.
  54. Several years ago,
  55. scientists were looking
    at how rats learned
  56. as they would run around a maze.
  57. And they were recording the activity
    in the memory centers of these rats.
  58. And as the rat was running
    around the maze,
  59. different brain cells would code
    different parts of the maze.
  60. And so if you added a tone
    to each one of the brain cells
  61. what you would hear
    as the rat was starting to learn the maze
  62. was the signature of that memory.
  63. So it would sound a little bit like ...
  64. (Bouncy piano music)

  65. It was this signature of learning
    that we could hear.

  66. But then they did something clever.
  67. They kept listening to the brain
    as these rats fell asleep,
  68. and what they heard was remarkable.
  69. The rat, as it was sleeping,
  70. started to replay
    that same memory signature.
  71. But now it started to replay it
    almost 10 times faster
  72. than it was doing when it was awake.
  73. So now instead you would start to hear ...
  74. (Fast bouncy piano music)

  75. That seems to be the second way

  76. in which sleep can actually
    strengthen these memories.
  77. Sleep is actually replaying
    and scoring those memories
  78. into a new circuit within the brain,
  79. strengthening that memory representation.
  80. The final way in which sleep
    is beneficial for memory

  81. is integration and association.
  82. In fact, we're now learning that sleep
  83. is much more intelligent
    than we ever imagined.
  84. Sleep doesn't just simply
    strengthen individual memories,
  85. sleep will actually cleverly interconnect
    new memories together.
  86. And as a consequence,
  87. you can wake up the next day
  88. with a revised mind-wide
    web of associations,
  89. we can come up with solutions
    to previously impenetrable problems.
  90. And this is probably the reason

  91. that you've never been told
    to stay awake on a problem.
  92. Instead, you're told
    to sleep on a problem,
  93. and that's exactly
    what the science teaching us.