Dr. Matthew Walker

And that's why you have really intense dreaming and you have these really crazy, bizarre experiences. Does your brain get back all of the REM sleep that it lost? No, it doesn't. It can only accumulate about 50% of the debt. So you will still be REM sleep deficient. REM sleep, it turns out, if you want to say... Give the head-to-head challenge, which is more important, non-REM versus REM?

Well, I'm going to firstly tell you that all stages of sleep are important. Different stages do different things at different times of night. But the ultimate test of what's more important is presumably death. How quickly do you die when you don't have one versus the other?

Well, I'm going to firstly tell you that all stages of sleep are important. Different stages do different things at different times of night. But the ultimate test of what's more important is presumably death. How quickly do you die when you don't have one versus the other?

Well, I'm going to firstly tell you that all stages of sleep are important. Different stages do different things at different times of night. But the ultimate test of what's more important is presumably death. How quickly do you die when you don't have one versus the other?

They did a series of studies back in the 1980s that will never be replicated again because I think they were just, you know, so barbaric. They started to sleep deprive rats to the point when they died. And what they found is firstly that rats will die as quickly of food deprivation as they will of sleep deprivation.

They did a series of studies back in the 1980s that will never be replicated again because I think they were just, you know, so barbaric. They started to sleep deprive rats to the point when they died. And what they found is firstly that rats will die as quickly of food deprivation as they will of sleep deprivation.

They did a series of studies back in the 1980s that will never be replicated again because I think they were just, you know, so barbaric. They started to sleep deprive rats to the point when they died. And what they found is firstly that rats will die as quickly of food deprivation as they will of sleep deprivation.

Sleep deprivation will kill you just as quickly as no food, about 11 days in the rats. Then they said, okay, let me now selectively just deprive the rats of deep sleep. So they still get REM sleep or they get deep sleep and we remove REM sleep. And when they looked at that, the rats died from REM sleep after about 20 days. So REM sleep was, you know, still lethal.

Sleep deprivation will kill you just as quickly as no food, about 11 days in the rats. Then they said, okay, let me now selectively just deprive the rats of deep sleep. So they still get REM sleep or they get deep sleep and we remove REM sleep. And when they looked at that, the rats died from REM sleep after about 20 days. So REM sleep was, you know, still lethal.

Sleep deprivation will kill you just as quickly as no food, about 11 days in the rats. Then they said, okay, let me now selectively just deprive the rats of deep sleep. So they still get REM sleep or they get deep sleep and we remove REM sleep. And when they looked at that, the rats died from REM sleep after about 20 days. So REM sleep was, you know, still lethal.

A lack of REM sleep was still lethal. Non REM sleep, they still died, but they died after about 60 days. So in other words, rats will die quicker from REM sleep deprivation than they will from deep non REM sleep deprivation. We all predicted the opposite in those studies. Why? Because I told you that non REM sleep was the original OG. in terms of the evolutionary course of sleep.

A lack of REM sleep was still lethal. Non REM sleep, they still died, but they died after about 60 days. So in other words, rats will die quicker from REM sleep deprivation than they will from deep non REM sleep deprivation. We all predicted the opposite in those studies. Why? Because I told you that non REM sleep was the original OG. in terms of the evolutionary course of sleep.

A lack of REM sleep was still lethal. Non REM sleep, they still died, but they died after about 60 days. So in other words, rats will die quicker from REM sleep deprivation than they will from deep non REM sleep deprivation. We all predicted the opposite in those studies. Why? Because I told you that non REM sleep was the original OG. in terms of the evolutionary course of sleep.

It was the first stage of sleep. So surely the first stage of sleep that emerged in the course of evolution would be the fundamental, elemental, most important. The opposite was true. Great study then back at Harvard. And what we find is that a lack of sleep, short sleep, as I said, shorter your sleep, shorter your life. And it's sort of a

It was the first stage of sleep. So surely the first stage of sleep that emerged in the course of evolution would be the fundamental, elemental, most important. The opposite was true. Great study then back at Harvard. And what we find is that a lack of sleep, short sleep, as I said, shorter your sleep, shorter your life. And it's sort of a

It was the first stage of sleep. So surely the first stage of sleep that emerged in the course of evolution would be the fundamental, elemental, most important. The opposite was true. Great study then back at Harvard. And what we find is that a lack of sleep, short sleep, as I said, shorter your sleep, shorter your life. And it's sort of a

It's a decaying curve, which is that, you know, the less sleep that you have, the higher and higher your death risk. But let's come back to that seven to nine hours of sweet spot because something odd happens. When you get past about nine, your death risk does not keep going down. it goes back up as if more sleep after nine hours is deathly.

It's a decaying curve, which is that, you know, the less sleep that you have, the higher and higher your death risk. But let's come back to that seven to nine hours of sweet spot because something odd happens. When you get past about nine, your death risk does not keep going down. it goes back up as if more sleep after nine hours is deathly.

It's a decaying curve, which is that, you know, the less sleep that you have, the higher and higher your death risk. But let's come back to that seven to nine hours of sweet spot because something odd happens. When you get past about nine, your death risk does not keep going down. it goes back up as if more sleep after nine hours is deathly.

And people have said, well, that's proof that sleep can actually kill you. If you look at the data, at least one of two things is happening in those studies. When you get sick, what is the first thing that you typically want to do? Sleep. Exactly.