Dr. Matthew Walker: The Science & Practice of Perfecting Your Sleep | Episode 31

There is no major psychiatric disorder that we can find in which sleep is normal ... There is a very intimate association between your emotional & mental health and your sleep health.

Alcohol is, because it's a sedative, what it's really doing is trying to essentially knock out your cortex. It's sedating your cortex, and sedation is not sleep. But when we have a couple of drinks in the evening, when we have a couple of nightcaps, we mistake sedation for sleep, saying 'Well, I always, when I have a couple of whiskeys or a couple of cocktails, it always helps me fall asleep faster.' In truth, what's happening is that you're losing consciousness quicker, but you're not necessarily falling naturalistically asleep any quicker.

When you fight biology, you normally lose—and the way you know you've lost is disease, sickness, and empowerment. And I think if you sleep in accordance with the natural biological edict that we've all been given, life tends to be both of a higher quality and a longer duration.

Alcohol is often used as a sleep aid for people who are struggling with sleep when things like over-the-counter remedies, etc., or herbal remedies have just not worked out for them. And alcohol, unfortunately, is anything but a sleep aid.

If you look at the contribution of different sleep stages to your lifespan, REM sleep was the strongest predictor of your longevity. And it was a linear relationship ... The less and less REM sleep that you were getting, the higher and higher your probability of death.

There were three really good randomized placebo crossover trials with tart cherries. And what they found was that in one study, it reduced the amount of time that you spent awake at night by over an hour. And in the other two studies, one of them found that it increased the amount of sleep that you got by 34 minutes; the other it increased the amount of sleep that you got by 84 minutes.

We found that for every 1 hour of sleep, extra sleep, that a woman gets, her interest in becoming sexually intimate with her partner increases by 14%.

What changes, to your question, is the ratio of non-REM to REM within that 90-minute cycle as you move across the night ... In the first half of the night, the majority of those 90-minute cycles are comprised of lots of deep non-REM sleep ... Once I push through to the second half of the night, now that seesaw balance changes, and instead, the majority of those 90-minute cycles are comprised either of this lighter form of non-REM sleep (stage 2 non-REM sleep) and much more, increasingly more, rapid eye movement sleep.

In sleep science, we think of sleep efficiency. So, of the total amount of time that you're in bed, how much of that percent time is spent asleep? And we usually look to numbers that are above 85% or more as a healthy sleep efficiency.

In order for us to fall asleep and stay asleep across the night, we do need to drop our core body temperature by about 1 degree Celsius or about 2 to 3 degrees Fahrenheit. And that's why it's always easier to fall asleep in a room that's too cold than too hot.

Difficulty and anxiety at night in the dark is not the same difficulty and anxiety in the light of day. And, when we have those thoughts at night, it comes with a magnitude of rumination and catastrophization that is disproportionate to that which you would describe when you are awake.

Sleep is probably the single most effective thing you can do to reset your brain and body health.

REM sleep is a fascinating time, which is another stage of sleep often called dream sleep, which is rapid eye movement sleep. That stage of sleep, some parts of your brain are up to 30% more active than when you're awake.

The great science of sleep in the past 5 or 10 years has has been 'Yes, quantity is important, but quality is just as important.' And you can't have one without the other in terms of a good beneficial next day outcome.

What if we started off sleeping, and it was from sleep that wakefulness emerged? Why do we assume that it's the other way around?

During deep non-REM sleep, that's where we get this—it's almost a form of natural blood pressure medication ... When I take that away from you, the next day, we're usually going to see autonomic dysfunction, we're usually going to see abnormalities in heart rate [and] blood pressure.

Both exercise and daylight are wonderful cues for circadian rhythm alignment and also circadian rhythm reset each day.

Naps can have some really great benefits. We found benefits for cardiovascular health—blood pressure, for example. We found benefits for levels of cortisol. We found benefits for learning & memory and also emotional regulation.

When you go into dream sleep, you are locked into a physical incarceration of your own body. Why would mother nature do such a thing? And it's, in some ways, very simple: The brain paralyzes the body so that the mind can dream safely.