Why do we spend one third of our lives asleep?

What does this have to do with living in an underground cave with no light,

or whether we can die from a lack of sleep, or the length of a day on Mars. Why are some people night owls and some

morning larks? How long is it possible to keep yourself awake physically? And why does the Guinness

Book of World Records no longer track that record.

Welcome to Inner Cosmos with me, David Eagleman.

I'm a neuroscientist and author at Stanford.

And in these episodes, we sail deeply into our three-pound universe to understand why and how our lives look the way they do.

Thank you. why and how our lives look the way they do. Today's episode is about sleep.

Why do we do it?

Why do we spend so much of our lives in this weird doppelganger state when you're asleep.

It still looks like you, but you are essentially shut off.

And even though we're not typically aware of being in this state, because we have no sense of the passage of time there,

we spend so much of our lives there more time than you spend

doing almost anything else, whether that's eating or showering or being with friends or listening

to podcasts. All of those presumably take up a smaller fraction of your life. Sleeping is at the top of your list of activities, and certainly

at the top of the list of activities that you do consistently. Other hobbies come and go,

sleep remains. So in today's episode, we're going to talk about everything you've ever wanted to know about sleep,

and we're going to uncover what the brain is really doing during this time.

And this is the first part of a three-parter.

Next week, we're going to dive into dreams.

Why do we dream? What's that about?

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