Matt Walker [ UC Berkeley ] I’m here to tell you about sleep — both the good things that happen when you get it and the alarmingly bad things that happen when you don’t.
But let me start with a disclaimer: It’s safe to say that, when most speakers look to their audience and see people who are falling asleep, nodding off soundly, it’s profoundly disheartening.
However, based on the topic of this presentation, I’m going to actively encourage that kind of behavior from you. It’s the greatest form of flattery for me, to see people like you not being able to resist the urge to strengthen what I’m telling you by falling asleep. So just eb and flow, in and out of consciousness. I take no offense.
Let me start with the brain and the functions of learning and memory. What we’ve discovered, over the past 20 or so years, is that sleep after learning is essential — to effectively hit the Save button on those new memories — so that you don’t forget.
But recently we’ve discovered that you also need sleep before learning — but now to prepare your brain, almost like a dry sponge, ready to soak up new information.
Without sleep, those memory circuits effectively become waterlogged and you can’t absorb information.
Let me show you the evidence. Here we’re going to test the hypothesis that pulling the all-nighter is a good idea. How do you do that? You take two groups of healthy young adults: a sleep group, and sleep-deprivation group. The sleep group is going to get a full eight hours of shut-eye across the night. The deprivation group, we’re going to keep awake all night in the laboratory under full supervision. No naps, no caffeine, it’s miserable for everyone involved.
Then the next day we are going to place them inside an MRI scanner and have them try and learn a whole list of new facts, as we’re taking snapshots of brain activity.
Then we’re going to test them, to see how effective that learning has been. And that’s what you’re looking at here — on the vertical axis — the efficiency of learning. The higher up you are, the more that you learned.
When you put those two groups head-to-head, what you find is a quite profound 40% deficit in the ability of the brain to make new memories without sleep .
This should be frightening, considering what we know is happening to sleep in education populations right now. Just to frame this in context, this would be the difference between acing an exam and failing it miserably.
We’ve gone on to discover what’s going wrong within the brain to produce these impairments.
There’s a structure on the left and the right side of your brain called the hippocampus. You can see it here in the orange yellow colors. Think of the hippocampus like the memory inbox of your brain. It’s very good at receiving new files and holding on to them. and when you look at this structure in those people who had a full night of sleep, here in green, you see lots of healthy learning-related activity.
Yet in those people who are sleep deprived, we couldn’t find any significant signal whatsoever.
It’s as though sleep deprivation had shut down your memory inbox. You couldn’t receive any new files. They were just being bounced.
In fact, if you want to know what life is like (by the way) without a functioning hippocampus, just watch the movie memento. I’m sure you’ve seen this: this gentleman suffered brain damage and, from that point forward, he can no longer make any new memories. He’s what we call densely amnesiac. The part of his brain that was damaged was the hippocampus. It is the very same structure that sleep deprivation will attack and block your brain’s capacity for new learning.
That’s the bad that happens when you take sleep away.
Let me just come back to that control group in green. Remember those people that got a full eight hours of sleep? We can ask a very different question: what is it about the physiological quality of sleep, when you do get it, that actually promotes and supports learning and memory?
By recording sleep with electrodes placed on the head, we discovered that there are big powerful brain waves that happened during a certain stage of sleep, that have riding on top of them these spectacular bursts of electrical activity.
It’s the combined quality of those sleeping brain waves, acting like a file transfer mechanism at night, that protects and refreshes your memory and learning each and every day.
It’s important that we understand what in sleep is transacting these memory benefits because there are real medical health implications
Let me just tell you about one that we’ve been moving this work out into — which is the context of aging and dementia. Why is that? Of course we all know that as we get older all learning and memory ability starts to deteriorate. What we’ve also known for a long time is that a physiological signature of aging is that your sleep gets worse.
Just recently we demonstrated that these two factors on not simply co-occurring — they are significant interrelated.
It suggests that sleep disruption is an under-appreciated factor that is contributing to memory decline in aging — and now it seems in Alzheimer’s disease as well.
I know this is remarkably depressing news, but don’t worry: there’s a silver lining here. We can do something about sleep. Sleep is a treatable target.
One way that we and others are now approaching this, in the future, is by using this: it’s called Direct Current brain stimulation. I kid you not. This is not science fiction. This is science fact. It’s a small electrical brain stimulator.
It’s an affordable portable piece of technology.
You insert electrodes into it and you insert some electrical stimulation into your brain.
If you apply that stimulation during sleep, in young healthy adults, as if you’re singing in time with those sleeping brain waves, not only do you amplify the size of those brain waves but, in doing so, you almost double the amount of memory benefit that you get from sleep .
The question now is whether we can translate this same technology into older adults and those suffering from dementia. Can we give back some healthy quality of sleep and in doing so can be salvaged their learning and memory function?
That’s the real hope now>
That is sleep for memory. What else is sleep good for? Let me tell you that sleep is critical to help stabilize and support your emotional and mental health . Without sleep those emotional circuits become hyperactive and irrational.
Allow me to demonstrate with a sleep-deprived subject.
We do video diaries with our participants, across the deprivation night, and you are going to meet one — under the pseudonym of Jeff
Jeff has just entered the study. It’s 11:30 at night, on day one. He’s been awake for a perfectly normal 16 hours. Let’s hear from Jeff about what his hopes and aspirations are for the deprivation night.
Hello. It’s about 11:27 right now. I’ve been here for about an. . . I think about an hour now. Yeh, about an hour. So it’s the first hour. I’m writing my paper right now. 30 page paper. Hopefully I can get some of it done before I get too sleepy.
That’s Jeff. Perfectly likable, affable, chap. He’s hoping to get his 30 page report completed in a night of sleep deprivation.
Classic delusional undergraduate thinking. I see it all of the time.
Now let’s fast forward the clock. It’s now 5:30 the following morning. Jeff has now been awake for 22 hours straight and instantly you’ll notice how emotionally different Jeff has become — almost pendulum-like it his emotional volatility.
Let’s hear from Jeff, how that thirty-page report has been going. I apologize ahead of time for the profanity.
Hello. I’m very angry right now. Because I didn’t get any [Bleep] can I curse on this? Whatever. [Laughter] [inaudible] I’m very lucid, actually.
So did you notice how Jeff went from being remarkably upset and annoyed that he’d got none of his 30 page report completed, to then finding it almost hilarious? He’s gotten punch-drunk giddy on sleep deprivation. And then he came right back down to baseline again.
That is a remarkably abnormal emotional distance to travel within such a short time period.
I think it emphasizes the destabilizing influence that a lack of sleep has on our emotional integrity .
We are beginning to understand why, what goes wrong within the brain, to produce this change. There’s a structure deep within the brain called the Amygdala. You can see it here in red. It’s one of the centerpiece regions for the generation of negative emotional reactions. If you look at the activity in this part of the brain, in those people who had a full night of sleep, here in green, you see a nice controlled, modest degree of response.
Yet in those people who were sleep deprived, in red, we saw an aggravated — almost neanderthal-like degree of reaction — a 60% amplification in responsivity .
It is as though without sleep you become all emotional gas pedal and too little control break as it were.
What’s more concerning is that this is a neurological signature that is not dissimilar to numerous psychiatric disorders. In fact, we’re now finding that the disruption is a significant predictor of conditions such as depression, anxiety (including PTSD), and tragically suicide as well. In fact, we cannot find a single psychiatric disorder were sleep is normal.
I think sleep has a powerful story to tell us in our future understanding, treatment, maybe even prevention of serious mental health illness.
I couldn’t walk away letting you think that sleep is just for the brain. It’s essential for the body.
Let me give you one example, which is within your immune system. Here I’ll introduce these delightful little blue elements. they are called natural killer cells. Think of natural killer cells like the secret service agents of your immune system. They are very good at identifying dangerous foreign elements and eliminating them.
What they’re doing right now is embedding themselves into a malignant cancerous tumor mass and destroying it.
So what you want is a virile set of these immune cells at all times. Sadly, that’s exactly what you don’t have — if you haven’t been sleeping enough.
Here in this study, you’re not going to be deprived of sleep for an entire night. You’re simply going to have your sleep restricted to 4 hours for single night — and then we’re going to look to see what percent reduction in immune cell activity you suffer.
It’s not small . It’s not 10%. It’s not 20%. There is a 70% reduction in natural killer cell activity .
And this happens quickly — essentially after just one bad night of sleep.
Imagine the state of your immune system after weeks, if not months, of bad sleep
And it’s perhaps not surprising that we’re now finding that insufficient sleep is a significant risk factor for the development of numerous forms of cancer. Indeed that relationship, that link between a lack of sleep and cancer, is now so strong that recently the World Health Organization decided to classify shift work, because of the disruption of your sleep rhythms, as a probable carcinogen.
Jobs that will induce cancer because of sleep disruption
So that old maxim that you’ve heard, “I’ll sleep when I’m dead” is mortally unwise advice.
In summary, I think the evidence is overwhelming. It’s irrefutable. Sleep is the single most effective thing you can do to reset your brain and body health, each and every day.
If you were to ask me what the future of sleep is, ironically I would tell you, it’s about a return to the past. Because in 1910 the average American adult was hitting the sweet spot of eight and a quarter hours of sleep a night
Now that number is closer to six and three quarter hours
The decimation of sleep throughout industrialized nations is having a catastrophic impact on our health and wellness.
It’s a silent sleep loss epidemic.
I believe it’s now time for us to reclaim our right to a full night of sleep without embarrassment, without the stigma of laziness.
And in doing so, we may remember what it feels like to truly be awake during the day.
With that, I will simply say goodnight, sleep well, thanks very much.