Sophie Scott

So you get a change in the uptake of the body's naturally circulating painkillers, which are endorphins.

And that's why you feel buzzy and good when you've been laughing.

It's exactly the same as anything you might do after exercise, which is when you also get an endorphin hit.

You get a runner's high when you've been laughing.

You also get a reduction in adrenaline and that endorphin buzz you get from any kind of laughter, even really fakes laughter.

It seems to be to do with how you're engaging your rib cage.

But you also get a change in adrenaline.

Adrenaline is that fight or flight hormone that makes your heart start racing.

and you're scared.

And that is lower after you've been laughing than it was before you were laughing.

While you're actually laughing, it tends to go up because you're doing quite a lot of work.

It's quite stressful for your heart when you're laughing.

You also get a reduction in cortisol associated with laughter.

Cortisol is a stress hormone.

It's what wakes you up in the morning.

It's why waking up in the morning can sometimes feel a bit grim.

And it's also the hormone that runs at high levels when you are feeling stressed and you sleep badly and your appetite goes over and you don't feel right.

That's cortisol at work.

And high levels of cortisol running chronically is not good for your mental health.

It's not good for your physical health.