So what we've spoken about is the first two of the three stages of memory processing with sleep, sleep before to get the brain ready to lay down memories, sleep after to grab a hold of those individual memories and cement them into the neural architecture of the brain. Once you've done that, though, there's a final step. And that seemed to not depend on deep non-REM sleep but instead depend on rapid eye movement sleep or REM sleep, which is what most of us know as dream sleep.

And it's during dream sleep that your brain essentially performs informational alchemy, is what I would describe it as. It's a little bit like group therapy for memories that sleep has gathered in all of the information during the day. And during non-REM sleep, which always comes first, by the way, in our sleep cycle. We always have non-REM sleep first, then REM sleep second, then non-REM sleep again, then REM sleep second.

And we don't know why there is no good explanatory data suggesting why non-REM sleep always comes first and REM sleep comes second. But I've put forward the theory that, for information processing, it makes sense. Which is that non-REM sleep first to just get what you've learned and lock it into the brain. REM sleep then comes along, and REM sleep starts to fuse all of the information that you've recently learned with the entire back catalog of information that you've got stored up across a lifetime of experience.

And it's this sort of...Essentially, REM sleep is creating a revised mind wide web of associations. And I'd like to sort of think of what's going on with REM sleep. And we've done lots of these studies to look at this and these clever ways that you can look at sleep and associative memory processing and building new novel connections. And it's almost like memory pinball, where you take these new memories and you sort of launch them up, and you start bouncing them around into the architecture of information within the brain. And you're starting to test associations. You're starting to say, you know, "Should this new information be connected to this? Maybe not. Should it be connected to this? Maybe not."

Now some of that happens whilst were awake during the day. We make obvious connections. But what's strange is that we make connections during REM sleep but they're not of the same kind. The connections that we're making during REM sleep are the longshots. This is the bizarre...

Rhonda: The bizarre, right.

Matt: ...strange. You know, it's sort of...it would be the equivalent of saying, during the day, we take this information, and the connections we make are like a Google search gone right, which is the first page is all of the things that are most related. And it's very obvious. Page 1, that's directly related to what I inputted.

During REM sleep, it's almost as though you input the search term and you're immediately taken to page 20 of the Google search, which is about some field hockey game in Utah. And you think, I don't understand. Oh, that's interesting. I see what you're talking about. So we make these bizarre leaps of associative memory processing faith during REM sleep. And that's why we now understand that it's REM sleep that helps us divine remarkable creative insights into previously impenetrable problems.

And you can see this throughout the history of human beings, this dream-inspired insight, scientific demonstrations. You know, August Kekulé divined the idea of a benzene ring, these double carbon rings by dreaming of a serpent that swallowed its tail. Dmitri Mendeleev, you know, came up with the Periodic Table of Elements by way of dream inspiration. And, you know, people have won Nobel Prizes, Otto Loewi won the Nobel Prize for the demonstration of chemical transmission across nerve cells. And he dreamt of the experiment that helped improve that. He didn't dream of the concept itself, but he dreamt of the experiment to prove it.

Wonderful, artistic demonstrations of this, too. You know, Paul McCartney has written innumerable songs, it turns out, by way of his dreams. Keith Richards came up with the opening chords of Satisfaction by way of dream-inspired insight.

So REM sleep takes that third component of information processing. And I think it's what defines us differentially from computers in part, which is that deep sleep is about knowledge, which is gathering all of the information and holding on to it. REM sleep, I would argue, is about wisdom, which is knowing what it all means when you fit it together, you know. That's what I want from a good student. Don't just give me dry-book learning. Do you really understand it? Can you apply it? Are you creative? That's dream sleep.