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REM sleep vs. deep sleep and their importance for cardiovascular and emotional health | Matt Walker

January 24, 2020

[Matt]: REM sleep takes a backseat. At sort of, you know, a bit of a neglected
stepsister in the sort of sleep conversation. REM sleep, we found all manner of different
functions, one of which is emotional first-aid. It’s incredible for palliative emotional benefit. It’s not time that heals all wounds, but it’s
time during REM sleep that provides emotional convalescence. [Rhonda]: I guess that would also then be
important to help you sleep better, because if you are managing your emotions better,
you probably have less anxiety… [Matt]: Correct. Exactly. But also REM is for the body, too, you know. It seems to regulate cardiovascular function. So REM sleep is critical too. [Rhonda]: Oh, really? Is REM what’s important for lowering the blood
pressure? [Matt]: No. Well, it’s during deep sleep that you get
this lowering of blood pressure, and we’ve got some data right now that we’re about to
publish that deep sleep provides actually a homeostatic recalibration of blood pressure. What do I mean by that? If I measure your blood pressure before sleep
and then after sleep at a matched circadian time, so we remove the circadian fluctuation
of which there is a large one to your systolic blood pressure, but we match it, and so the
only thing that’s different is the quality of your sleep, what we’ve discovered firstly
is that the amount of deep sleep that you have measured in these big delta slow waves
during deep non-REM sleep, that predicts how much of a drop in your systolic blood pressure
you will have in the morning relative to the evening as if deep sleep provides a recalibration
of the cardiovascular system. [Rhonda]: Wow. [Matt]: If you’re having higher frequency
brainwaves that are not like the deep sleep, that’s what we call unrestorative sleep, if
you have a ratio of very little deep brainwave activity and a lot of high-frequency wake-like
brain activity, what we call delta-beta ratio that predicts very bad cardiovascular outcomes,
that if anything, your systolic blood pressure is even worse after sleep than it is the night
before. And what we found is that during aging, now
we looked at this and healthy people, then we replicated in older adults, and we found
that the older that you get, the less deep sleep that you get, the more sort of wake-like
or faster-frequency brainwave activity, which isn’t good during deep sleep. And that accurately predicts the cardiovascular
dysfunction that we see in aging. So we now think we understand in part why
poor sleep is linked into poor cardiovascular outcomes. One of the benefits of sleep is that it resets
cardiovascular tone and particularly systolic tone. It doesn’t stop there. There’s lots of other benefits, heart rate
drops, etc. But REM sleep also seems to have this strange
function where you go through these cycles where you get a massive activation of the
cardiovascular system, and then it falls silent, and then a massive escalation again. And you get this really remarkable increase
in heart rate variability. And heart rate variability has been used as
a metric of health outcome, that if you have high current rate variability, it’s very good. It predicts lots of health outcomes. That’s what you get during REM sleep. So we should be careful not to think of everything
being all about deep sleep. It’s about all stages. Every stage of sleep that we have, we have
ascribed a function to. Which makes sense, you know, during sleep…Sleep
is the most idiotic of all things in terms of a creation from Mother Nature. You know, you’re not finding a mate. You’re not reproducing. You’re not eating. You’re not caring for your young. And worse of all, you’re vulnerable to predation. So on any one of those grounds, sleep should
have been strongly selected against in the course of evolution. The exact opposite is true. Every species that we’ve studied to date sleeps. What that means is that sleepers fought its
way through heroically every step along the evolutionary pathway, which must mean that
if sleep doesn’t serve an absolutely vital function, it is the biggest mistake that the
evolutionary process has ever made. And if any one of those stages of sleep could
be removed, because it was not important, because I want to, you know, emphasize this
type of sleep because that other sleep must not be important, I promise you, mother nature
would have thought, I’m gonna excise that stage of sleep out because you’re just too
vulnerable. But I think, in your position, of course I
would be concerned about my deep sleep, thinking about things like apoe-4 Alzheimer’s risk,
too. But I think the bottom line is that no matter
which way you slice the sleep pie, you just can’t shortchange sleep.


  • Reply FMF Clips February 28, 2019 at 3:54 pm

    Watch the full episode:

    FoundMyFitness episode page:

    More clips from this guest:

  • Reply Joel Mounts March 3, 2019 at 2:36 pm

    It's cool seeing stage info from sleep trackers and seeing how it gets affected. I love dreaming and try to recall the 3-4 dreams I have during my 3-4 REM segments each night.

  • Reply antichrist pug March 25, 2019 at 2:59 pm

    awesome content, you are truly making a change by bringing this to our awareness

  • Reply AlmostABeast665 June 4, 2019 at 12:46 pm

    I heard so many people claiming "it doesn't matter how long you sleep, it's important how much REM you have". Thanks for this video.

  • Reply christian monturano II December 6, 2019 at 8:12 am

    Look at the people and cars outside the window am I dreaming

  • Reply Richard Middleton December 6, 2019 at 12:23 pm

    I have had an Oura ring for a week now and even if I get 8 hours sleep I only get less than an hour of REM but I get 1.5 – 2 hours of deep. I do wake multiple times at night which is down to my wife coughing, snoring, moving around, singing, talking you name it! 😡. Wearing ear plugs is helping and I'm thinking of getting a new mattress.

  • Reply Boi Mesa January 5, 2020 at 11:03 pm

    Ehm…. English pls???

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