Here is the full transcript of neuroscientist Penny Lewis’ TEDx Talk Presentation on Sleep-Engineering: Improve Your Life By Manipulating at TEDxGrandRapids conference. Dr. Penny (Penelope) Lewis is a neuroscientist at the University of Manchester and is the author of The Secret World of Sleep. To learn more about the speaker, read the full bio here.
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Penny (Penelope) Lewis – Neuroscientist
You know, for a sleep scientist, I actually don’t sleep very well. Any little chink of light in the room and I’m awake all night. And my eye mask is just as important to me as my laptop. But really I take sleep very seriously, and I’m hoping this talk will be a sort of a wake-up call to all of you, to make some of you feel the same about it.
Now, what I’m not going to do is preach to you about how you should get more sleep. We all know that; we all know we live in a sleep-deprived society.
Instead, I’m going to talk about something which I think is much more interesting. This is how we can manipulate the sleep that we do get in order to get the most out of it, in order to improve our quality of life and I call this the New Science of Sleep Engineering.
But let’s start from the beginning. As humans, we spend roughly a third of our lives of sleep, eight hours a day. That’s more time than we spend doing anything else. That’s a huge amount of time. And just the pure fact of that time investment suggests that sleep must be doing something incredibly important.
Sleep is All About The Brain
But what is this? Well, it turns out that sleep is all about the brain. Contrary to popular opinion, the brain doesn’t just switch off when we go to sleep. Instead it goes through a series of highly specific different types of activities. We can measure these by putting electrodes all over the scalp like this. This by the way is a sleep scientist’s idea of a selfie.
With these electrodes, we can measure the electrical activity of the brain, and during wake it looks something like this, just a wiggly line, with time going from left to right. And what that tells us is the brain is active, good — and that the activity is not particularly synchronized. So things aren’t summing up in any particular way.
But as we fall asleep, the pattern changes a little bit. It slows down a little bit and the amplitude of those brain waves gets a little bit higher showing a bit more synchrony. And we also start to see occasional bursts of high-frequency activity that we call Sleep Spindles. These spindles don’t occur across the whole brain; they just occur in localized areas at any one time. And I’m going to come back to them several times during the talk to try and remember what those look like.
Now as we go deeper into sleep, the activity slows down still more. And we start to see these high amplitude slow oscillations that we call Slow Waves. And this shows a high degree of synchrony in the firing across the cortex. Many neurons are all firing together, then pausing, then firing together. It’s very different than the kind of activity that we see during awake.
And if we go still deeper, we go into a sleep stage that I’m sure you’ve all heard about Rapid Eye Movement Sleep. This is famous for the way the eyes dart around under closed lids. And it actually looks very similar to the brain activity that we see during wake, probably because of all the dreaming that’s happening, not much cortical synchrony.
So why do we do this? Why do our brain spend a third of our life going through these highly precise different types of activity in a cycle from one stage to another?
Well, there are two main answers to this. One of them relates to sleep’s role in maintaining a healthy brain; and the other to its role in learning and memory. And I’m going to start by talking about the healthy brain.
Sleep plays sort of a housekeeping role. It cleans our brains. It helps us to remove toxins. And some of the most interesting studies of this have shown that the spaces between brain cells expand during that slow wave sleep I showed you by as much as about 60%. And this allows cerebrospinal spinal fluid (CSF), the fluid in the brain, to flush through and efficiently clear away toxins that have built up during wake.
One of these toxins that’s particularly interesting is something you might have heard about: beta amyloid. This is a protein that can build up not only during wake but actually across a lifetime and build-ups of beta-amyloid are linked to the formation of plaques in the brain that are predictive of cognitive impairment, particularly problems with memory. If it gets bad, it’s also linked to dementia and Alzheimer’s disease.
Beta amyloid is also linked to cell death in the brain and a gradual degeneration of some parts of the cortex that can happen with aging — again in dementia and Alzheimer’s disease. So it’s obvious that it’s important for us to flush this out of the brain if we possibly can.
Now, interestingly, as we age our sleep patterns also change. As sleep becomes more fragmented and those high amplitude slow oscillations that I told you about gradually stretch and flatten out and after the age of 65 or so is quite common not to get any more slow wave sleep at all; problem, right?
Furthermore, this gradual decline in slow wave across the life cycle has been shown to predict the extent to which the cortex actually attributes and shrinks. So some of the prefrontal regions of the cortex and that shrinkage is predicted by the decrease in slow wave sleep.
So wouldn’t it be great if there was a way that we could maintain those slow waves as we got older and not have that decline? And this is where we come to sleep engineering.
Very recent research has suggested a way that we can do this. If we play sounds to people, just click — simple click sounds while they’re in slow wave sleep, and if we place those sounds near the peaks of those high amplitude slow oscillations, it turns out that it can enhance them. Let me show you what this looks like.
So the clicks occurring just near the peak boost the amplitude and they’ve also been shown to improve memory the next day. That works very well in healthy young people. And I’ve got several quite sleep-deprived graduate students who are working hard on taking this to the older population. And right now our results are very promising. So we’re hoping that in not too many years we might be able to offer a sort of a preventative treatment that could help people to maintain their slow wave sleep as they get older, and possibly might slow down some of this decline — cortical and cognitive that happens.
So let me move on now to talk about learning and memory. And in his famous book One Hundred Years of Solitude, Gabriel García Márquez wrote about a plague of insomnia that swept across the land. People just couldn’t sleep and at first they didn’t mind that at all. But eventually negative symptoms started to manifest and these symptoms were the fact that they lost their memories. They couldn’t learn new things and they started to forget what objects were; they had to cover things with note, saying things like ‘This is a cow; it gives milk, pull here.’
Given that this book was published in 1967 when we knew almost nothing about sleep’s role in memory, it’s really quite remarkable that Garcia Marquez had insight into this. But subsequent research has shown that he was absolutely right. Sleep is very important for forming new memories and also integrating those memories with what we know already, also strengthening memories.