Sleep. You know it, you love it, and most of us do it every night. But for something that every person on the planet experiences, the scientific study of sleep is surprisingly complex. There are a lot of theories out there about why we need sleep and what the evolutionary functions of sleep have been throughout the history of our species.

Some research says that we need sleep in order to process our memories.

Others suggest it's an opportunity for our bodies to metabolize or for our brains to prune or even clear out waste after a long day.

No matter the theory,

we can all agree that sleep is one of the most important things that our bodies do.

So, for this episode of Curiosity Weekly, we'll be diving into the science of sleep.

I'll speak with Dr. Jeffrey Iliff, who is part of the research team that discovered the glymphatic system,

which is all about how our brain

cleanses itself through sleep. I'll also dig into a new study that proposes five different

sleep types and how they affect our mental and bodily processes. Plus, we'll explore how we can

learn more about human sleep patterns from studying the fun and different ways that animals sleep. My name is

Dr. Samantha Eamene. Let's dive in. Did you know jellyfish don't sleep? Well, not in the same way

that you and I do. Or how about dolphins? They only rest half their brains at a time. Talk about

multitasking. Most animals sleep, but not all of them, and we're not exactly

sure why. From the tiniest fruit fly to the majestic tiger or the stealthy bat to the drifting jellyfish,

not all animals sleep the same. Some aren't thought to sleep at all, at least not in the way we

typically think of sleep. Understanding the diverse ways animal sleep could unlock new treatments for sleep disorders,

sleep medication, and help us all get some shut-eye.

Previous research looked at the big picture, the cost and benefits of how animals sleep.

And then they honed in on two different factors that led to these behaviors,

the threat of predation and the promise of food. When it comes to predation,

for example, animals will sleep longer if they're in a protected place like a burrow or tree top.

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