Okay, so multiple times throughout today's discussion, we've been talking about how exercise increases arousal, arousal improves brain function, that's true. You know what's also true? What's also true is that exercise improves brain health in the long-term, yes, through the deployment of things like BDNF, yes, through the deployment of things like osteocalcin and on and on, but it also does so by improving your sleep.

One question I get a lot is let's say I don't sleep that well, should I exercise? Well, the short answer is yes, provided that it was just one night of poor sleep. In fact, there are studies showing that if you're slightly sleep deprived, meaning one night's poor sleep, so most people need somewhere between six and nine hours of sleep, varies by person, varies by age, varies by time of year and so on, all discussed in that series with Matt Walker.

Most people need six to nine hours, but let's say you normally get eight or you normally get seven, but you're down two hours on sleep for whatever reason, should you exercise the next morning? The short answer is yes, provided it was just one night of poor sleep. It turns out that exercising after a poor night's sleep can help offset some of the negative effects of sleep deprivation on what?

On brain performance and health. Now, you don't want to get into a habit of this. You don't want to get into a habit of using exercise as a way to compensate for sleep loss. So if you don't sleep well for one night, exercise is a great way to offset that sleep loss effect on the brain or that would otherwise affect the brain.

You can compensate for it by doing some exercise. Keep in mind, you want to exercise in a way that's not too intense because you can drive your immune system down and be more vulnerable to infections. That's certainly the case after a poor night's sleep. You also want to be really careful with what you do for that exercise in terms of your coordinated movement.

It's much easier to get injured when you're sleep deprived. In fact, there's a really nice set of studies. Lane Norton's talked about this elsewhere, that the relationship between sleep, or I should say sleep deprivation and injury is a strong one. And the relationship between sleep loss and pain and failure to recover from injury is also a strong one.

The direct point being, if you're slightly sleep deprived, sure, go ahead and exercise. That will actually help you offset some of the negative effects of that sleep deprivation, but you want to be careful how you exercise so you don't get sick and you don't get injured. And there are actually studies of how quickly your brain starts to suffer if you don't exercise.

And the major thing that I was able to extract from that literature is that after about 10 days of not doing any training, that is no cardiovascular training, no resistance training, you start to see significant decrements in brain oxygenation levels, as well as some other markers that are indicative of brain health, or that would be indicative of brain health if they were to continue.

So if you haven't been training at all for a long period of time, your brain is suffering. The good news is you can start benefiting your brain very quickly by exercising. So you can keep in mind that if you're having trouble sleeping, or even if you're a great sleeper already, getting exercise will further improve the architecture of your sleep.

In fact, there's some evidence that doing high intensity interval training can improve the amount of deep slow wave sleep that you get. And there's some additional data showing that if you do high intensity training early in the day, and that's combined with a bunch of other things that stimulate autonomic arousal, so here we are again at autonomic arousal, things like caffeine, if that's in your program, you don't have to drink caffeine.

Things like getting bright light in your eyes early in the day, definitely do that. Don't stare at the sun or any light so bright that it's dangerous or painful to look at, but certainly get bright light in your eyes. All those things that increase autonomic arousal early in the day can also help improve the amount and the quality of sleep that you get at night, in particular, rapid eye movement sleep, which is so critical for learning and memory.

In fact, there's something called the first night effect, which is the amount and quality of rapid eye movement sleep that you get on the first night after trying to learn something, powerfully dictates whether or not you actually learn and remember that thing. Because as you recall, learning and memory, neuroplasticity is a two-step process.

You need to be focused and alert during the encoding phase, during the learning, but it's in states of deep rest, sleep in particular, but also non-sleep deep rest, but rapid eye movement sleep is the kind of king of reshaping your brain connections for the better. Unloading the emotional load of experiences that were troubling, that happens during rapid eye movement sleep.

Just a little bit of REM deprivation, rapid eye movement sleep deprivation will make you more emotional and will make the painful experiences of recent and distant past also more painful. Get more rapid eye movement sleep if you can. It also consolidates learning of things that you want to remember.

Again, exercise early in the day, in particular, high intensity exercise combined with some of the other things we just discussed, terrific way to improve the amount and quality of sleep that you get at night. And of course, all of that geysers up to what? Better brain health and performance in the short-term and in the long-term.

There are now many, many studies showing that sleep is the thing that mediates many, not all, but many of the positive effects of exercise on brain performance and long-term brain health. So what this means is that you have to make sure that you're getting adequate amounts of sleep. It's not sufficient just to exercise.

You need to get proper sleep. And I've done multiple episodes on how to optimize your sleep, how to improve your sleep, how to deal with insomnia, shift work. If you want to learn about any and all of that, either from podcasts or from our newsletter, go to hubermanlab.com, put sleep into the search function, and it will take you to the episodes and the newsletters that discuss that.

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