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Welcome to Brain Stuff, a production of IHeart Radio.

Hey, Brainstuff, Lauren Vogelbaum here.

Laughter can be contagious, which can lead to some happy, good times.

As social animals, we humans laugh a lot more heartily when others are laughing too,

but laughter isn't always a gleeful response.

Like other more negative-coded symptoms, like crying, fainting, and shortness of breath,

it can be a sign that someone is feeling really distressed.

In January of 1962, in a small British-run boarding school in a remote town on the coast of

Lake Victoria in what's now Tanzania, three girls began laughing, possibly in response to a joke,

and couldn't stop.

Soon, the fit of giggles spread to their classmates until nearly 60% of the students were

experiencing a rare collection of symptoms.

The students were restless, alternating between uncontrollable bouts of laughter and sobbing

that lasted from a few minutes

to a few hours at a time. Some of the girls experienced other symptoms like physical pain,

respiratory problems, fainting, and rashes. Psychologists, doctors, and other scientists were called

in, all of them at a loss for an explanation for what was happening.

No toxins or other environmental factors seemed to be causing the laughter epidemic, and all of the girls' lab tests came back normal.

By March, the school officials gave up and requested that parents take their daughters home.

But as the girls fanned out into their respective communities around the country,

...