0:00:00.130,0:00:02.572 Whether you're cramming for an exam 0:00:02.596,0:00:05.777 or trying to learn[br]a new musical instrument 0:00:05.801,0:00:08.436 or even trying to perfect a new sport, 0:00:08.460,0:00:12.166 sleep may actually be[br]your secret memory weapon. 0:00:12.190,0:00:14.999 [Sleeping with Science] 0:00:17.180,0:00:21.327 Studies have actually told us[br]that sleep is critical for memory 0:00:21.351,0:00:23.171 in at least three different ways. 0:00:23.195,0:00:26.566 First, we know that you need[br]sleep before learning 0:00:26.590,0:00:28.686 to actually get your brain ready, 0:00:28.710,0:00:31.113 almost like a dry sponge, 0:00:31.137,0:00:33.796 ready to initially soak up[br]new information. 0:00:33.820,0:00:37.526 And without sleep, the memory[br]circuits within the brain 0:00:37.550,0:00:40.506 effectively become[br]waterlogged, as it were, 0:00:40.530,0:00:43.276 and we can't absorb new information. 0:00:43.300,0:00:47.326 We can't effectively lay down[br]those new memory traces. 0:00:47.350,0:00:51.146 But it's not only important[br]that you sleep before learning, 0:00:51.170,0:00:54.766 because we also know[br]that you need sleep after learning 0:00:54.790,0:00:58.106 to essentially hit the save button[br]on those new memories 0:00:58.130,0:00:59.686 so that we don't forget. 0:00:59.710,0:01:04.336 In fact, sleep will actually[br]future-proof that information 0:01:04.360,0:01:05.716 within the brain, 0:01:05.740,0:01:07.741 cementing those memories 0:01:07.765,0:01:11.236 into the architecture[br]of those neural networks. 0:01:11.260,0:01:13.090 And we've begun to discover 0:01:13.114,0:01:19.716 exactly how sleep achieves[br]this memory-consolidation benefit. 0:01:19.740,0:01:24.966 The first mechanism[br]is a file-transfer process. 0:01:24.990,0:01:27.816 And here, we can speak about[br]two different structures 0:01:27.840,0:01:28.996 within the brain. 0:01:29.020,0:01:31.876 The first is called the hippocampus 0:01:31.900,0:01:34.676 and the hippocampus[br]sits on the left and the right side 0:01:34.700,0:01:35.976 of your brain. 0:01:36.000,0:01:37.936 And you can think of the hippocampus 0:01:37.960,0:01:41.586 almost like the informational[br]inbox of your brain. 0:01:41.610,0:01:44.376 It's very good at receiving[br]new memory files 0:01:44.400,0:01:45.776 and holding onto them. 0:01:45.800,0:01:48.266 The second structure[br]that we can speak about 0:01:48.290,0:01:49.786 is called the cortex. 0:01:49.810,0:01:53.666 This wrinkled massive tissue[br]that sits on top of your brain. 0:01:53.690,0:01:55.776 And during deep sleep, 0:01:55.800,0:01:58.656 there is this file-transfer mechanism. 0:01:58.680,0:02:01.686 Think of the hippocampus like a USB stick 0:02:01.710,0:02:04.496 and your cortex like the hard drive. 0:02:04.520,0:02:06.466 And during the day, we're going around 0:02:06.490,0:02:08.416 and we're gathering lots of files, 0:02:08.440,0:02:10.956 but then during deep sleep at night, 0:02:10.980,0:02:13.586 because of that limited storage capacity, 0:02:13.610,0:02:17.106 we have to transfer those files[br]from the hippocampus 0:02:17.130,0:02:20.156 over to the hard drive[br]of the brain, the cortex. 0:02:20.180,0:02:22.436 And that's exactly one of the mechanisms 0:02:22.460,0:02:24.516 that deep sleep seems to provide. 0:02:24.540,0:02:28.196 But there's another mechanism[br]that we've become aware of 0:02:28.220,0:02:31.686 that helps cement[br]those memories into the brain. 0:02:31.710,0:02:34.026 And it's called replay. 0:02:34.050,0:02:35.216 Several years ago, 0:02:35.240,0:02:39.225 scientists were looking[br]at how rats learned 0:02:39.249,0:02:41.316 as they would run around a maze. 0:02:41.340,0:02:45.796 And they were recording the activity[br]in the memory centers of these rats. 0:02:45.820,0:02:48.146 And as the rat was running[br]around the maze, 0:02:48.170,0:02:52.726 different brain cells would code[br]different parts of the maze. 0:02:52.750,0:02:56.422 And so if you added a tone[br]to each one of the brain cells 0:02:56.446,0:03:00.086 what you would hear[br]as the rat was starting to learn the maze 0:03:00.110,0:03:02.106 was the signature of that memory. 0:03:02.130,0:03:04.173 So it would sound a little bit like ... 0:03:04.197,0:03:07.696 (Bouncy piano music) 0:03:07.720,0:03:11.876 It was this signature of learning[br]that we could hear. 0:03:11.900,0:03:14.626 But then they did something clever. 0:03:14.650,0:03:19.236 They kept listening to the brain[br]as these rats fell asleep, 0:03:19.260,0:03:21.668 and what they heard was remarkable. 0:03:21.692,0:03:23.816 The rat, as it was sleeping, 0:03:23.840,0:03:28.676 started to replay[br]that same memory signature. 0:03:28.700,0:03:33.066 But now it started to replay it[br]almost 10 times faster 0:03:33.090,0:03:35.236 than it was doing when it was awake. 0:03:35.260,0:03:37.613 So now instead you would start to hear ... 0:03:37.637,0:03:40.636 (Fast bouncy piano music) 0:03:40.660,0:03:42.656 That seems to be the second way 0:03:42.680,0:03:45.896 in which sleep can actually[br]strengthen these memories. 0:03:45.920,0:03:50.376 Sleep is actually replaying[br]and scoring those memories 0:03:50.400,0:03:52.726 into a new circuit within the brain, 0:03:52.750,0:03:55.586 strengthening that memory representation. 0:03:55.610,0:03:58.936 The final way in which sleep[br]is beneficial for memory 0:03:58.960,0:04:01.746 is integration and association. 0:04:01.770,0:04:03.586 In fact, we're now learning that sleep 0:04:03.610,0:04:06.696 is much more intelligent[br]than we ever imagined. 0:04:06.720,0:04:10.906 Sleep doesn't just simply[br]strengthen individual memories, 0:04:10.930,0:04:15.776 sleep will actually cleverly interconnect[br]new memories together. 0:04:15.800,0:04:17.007 And as a consequence, 0:04:17.031,0:04:19.006 you can wake up the next day 0:04:19.030,0:04:24.216 with a revised mind-wide[br]web of associations, 0:04:24.240,0:04:29.546 we can come up with solutions[br]to previously impenetrable problems. 0:04:29.570,0:04:31.131 And this is probably the reason 0:04:31.155,0:04:35.726 that you've never been told[br]to stay awake on a problem. 0:04:35.750,0:04:39.616 Instead, you're told[br]to sleep on a problem, 0:04:39.640,0:04:42.103 and that's exactly[br]what the science teaching us.