I'm sure that a lot of you out there are like me and enjoy reading for a while before you go to sleep at night.

And I'm willing to bet that some of you are also like me and sometimes you fall asleep while you're reading,

which is usually followed by the unpleasant shock of a book or an e-reader or a phone

smacking into your nose.

If you're one of us, I have a question.

Do you ever hallucinate just a little while you're trying to read in that in-between state

between being awake and being asleep?

Because this happens to me all the time. Maybe it's because I read a lot

and I'm always tired, but I'll be there reading and I'm struggling to keep going and I restart

the page again and I'm nodding off. And I'm pretty sure my brain starts to invent paragraphs that

aren't there. And I don't remember them, but I know that it happens.

Now, thanks to Quanta staff writer Yasmin Saplicolu, I know the name of that feeling.

It's called a hypnagogic state.

And apparently it can lead to things like dreamy hallucinations or enhanced creativity. It's like dreams get blurred into waking time. And some famously creative people like Salvador Dali and Thomas Edison used to actively try to get into this state to get their brains working in new ways.

Welcome to the Quantum Podcast, where we explore the frontiers of fundamental science and math.

I'm Samir Patel, editor-in-chief of Quantum Magazine.

The story that Yasmin wrote for us that I'm referring to here was about more than groggy almost sleep.

It explains the latest understanding in how the brain makes transitions between sleep and wakefulness or between stages of sleep and some of the things that can go wrong in the process.

She's here to talk to us about that story today called How the Brain Moves from Waking Life to Sleep and Back again.

Welcome back to the show, Yasmin.

Hi, thanks for having me back.

As we always like to start, can you tell us what's the big idea here?

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