There's a number of different hormones associated with the different stages of sleep. We know that melatonin is a hormone of nighttime that makes us sleepy. What about growth hormone release? When does that occur during sleep? So growth hormone release happens all day long and all night long. But the deep slow-wave sleep that you get, the very first sleep cycle is when you get a big bolus of growth hormone release.

And in men and women equally. And if you miss that first deep slow-wave sleep period, you also miss that big bolus of growth hormone release. And you might get ultimately across the day just as much overall growth hormone release. But endocrinologists will tell you that big boluses do different things than a little bit eked out over time.

So that is when we know there's also a big push to synthesize proteins. So that's when the protein synthesis part that builds memories, for example, in our brain happens in that first cycle of sleep. So you don't want to miss that, especially if you've learned something really big and needs more synaptic space to encode it.

How would somebody miss that first 90 minutes? Sleep-depriving themselves. Yeah. So let's say I normally go to sleep at 10 p.m. And then from 10 to 11.30 would be this first phase of sleep. And that's when the big bolus of growth hormone would be released. Does that mean that if I go to sleep instead at 11.30 or midnight, that I miss that first phase of sleep?

Yeah. Why is it not the case that I get that first phase of sleep just simply starting later? It is a beautiful clock that we have in our body that knows when things should happen. And every cell in our body has a clock. And all of those clocks are normally synchronized.

And the circadian clocks are synchronized. And so our cells are ready to respond to that growth hormone release at a particular time. And if we miss it-- and it's a time in relation to melatonin also. So if you miss it, yeah, you might get some growth hormone release. But it's occurring at a time when your clock has already moved to the next phase.

And so it's just a clock thing. Yeah. I don't think we can overstate the importance of what you just described. And to be honest, despite knowing a bit about the sleep research and circadian biology, this is the very first time that I've ever heard this, that if you normally go to sleep at a particular time and growth hormone is released in that first phase of sleep, that you can't simply initiate your sleep bout later and expect to capture that first phase of sleep.

Yeah. So this is incredible and, I think, important and, as many listeners are probably realizing, also highly actionable. So what this means is that we should have fairly consistent bedtimes in addition to fairly consistent wake times. Is that right? Yes. Exactly. And in fact, one of the best markers of good neurological health when we get older is consistent bedtimes.

Wow. OK. I don't want to backtrack, but I did write down something that I think is important for me to resolve or for you to resolve. So I'm going to ask this. People that sleep nine hours or more, perhaps that reflecting an issue, some underlying issue, perhaps, is being a teenager or an adolescent and undergoing a stage of development where there's a lot of bodily and brain growth, an exception to that, because I don't recall sleeping a ton when I was a teenager.

I had a ton of energy, but I know a few teenagers and they sleep a lot. Yeah. Like they'll just sleep and sleep and sleep and sleep. Should we let them sleep and sleep and sleep? OK. Let them sleep. OK. So that's the one exception. What about us? Just like babies.

OK. When you're developing something in your brain or the rest of your body, you really need sleep to help organize that. I mean, sleep is doing really hard work in organizing our brains and making it develop right. And if we deprive ourselves of sleep, we will actually also just like I said, we have a daily clock, we also have a developmental clock, and we can miss a developmental window if we don't let ourselves sleep extra like we need to.

What other things inhibit growth hormone release or other components of this first stage of sleep? In other words, if I go to sleep religiously every night at 10 p.m., are there things that I perhaps do in the preceding hours of the preceding day, like ingest caffeine or alcohol that can make that first stage of sleep less effective even if I'm going to sleep at the same time?

Alcohol definitely will do that because alcohol is a REM sleep suppressant, and it even suppresses some of that stage two transition to REM with those sleep spindles. And those sleep spindles, we didn't talk about their function yet, but they're really important for moving memories to our cortex. It's a unique time when our hippocampus, the sort of like the RAM of our brains, writes it to a hard disk, which is the cortex.

And it's a unique time when they're connected. So if you don't want to miss that, you don't want to miss REM sleep, which is also a part of the consolidation process and schema changing process. And alcohol in there, you know, before we go to sleep will do that. Until we've metabolized alcohol and put it out of our bodies, it will affect our sleep badly.

It's probably fair to say no ingestion of alcohol within the four to six hours preceding sleep given the half-life, or it all would be better, but I know some people refuse to go that way. And maybe a little bit is okay. I don't know what the dose response is, but there are studies out there you can look at.

Great. So we're still in the first stage of sleep, and I apologize for slowing us down, but it sounds like it's an incredibly important first phase of sleep. What about the second and third 90-minute blocks of sleep? Is there anything that makes those unique? What is their signature besides the fact that they come second and third in the night?

There's more and more REM sleep the later, the night we get. There's also a change in hormones, you know, the growth hormone and melatonin levels are starting to decline, but other hormones are picking up. So it is a really different stage that you also don't want to shortchange yourself on.

And I think that's the stage many studies are showing that those are the times in sleep when the most creativity can happen. That's when our dreams can incorporate and put together old and new things together into a new way, and our schema are built during that time. So yeah, we can change our minds best during those phases of sleep.

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