Hi there, it's Matt Walker here and welcome back to the podcast.

Today is going to be the first of a two-part episode series all about sleep, eating, and body weight.

So let's just get right into it.

You've probably noticed a desire to eat more when you're not getting sufficient sleep,

and this is not a coincidence.

Some rather fiendish changes will unfold within both your brain and your body when sleep gets short

and it will lead to a path of potential overeating and as a consequence weight gain.

The first issue concerns two appetite regulating hormones called Leptin and Grellin.

Now, I often joke, they actually sound to me more like two

Hobbets from Lord of the Rings, but I promise you they are actually real hormones.

Leptin will send a satiety signal to your brain,

which in other words in plain speak means

that it sends a signal of fullness.

So when Leptin levels are high, your appetite is reduced and as a result you feel satisfied by the food that you've eaten.

Grellin in contrast does the exact opposite. Grellin will rev up your hunger and And so when growling levels are high, you don't feel

satisfied by the food that you just ate and as a result you'll want to eat more.

And sadly these two hormones go in opposite

directions when you're not getting sufficient sleep. So if we limit people,

healthy individuals to let's, four or five hours of sleep a night for a few

nights, what happens?

First we see a marked reduction in Lepton.

Lepton levels will drop by about 18%. And Leptin, as you will remember, tells your

...