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.
Listen to the MP3 Audio: Sleep-Engineering- Improve Your Life By Manipulating Your Sleep by Penny Lewis at TEDxGrandRapids
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.