There’s arguably no single hormone that has grabbed hold of the collective consciousness as much as cortisol.

Social media is overflowing with information about the evils of cortisol: it messes with your face, your belly, your sleep, your skin, and, perhaps most concerning, your fertility.

There’s no shortage of gimmicks available to help fight this hormone: cortisol masks, cortisol diets, cortisol watches, cortisol-suppressing supplements.

But the widely held view that cortisol always causes problems with reproduction hinges on a key assumption that hasn’t been tested. Our new review, published in Journal of Experimental Biology, provides evidence that this assumption is flawed. In fact, cortisol may actually promote healthy reproduction.

The hormone we love to hate

Cortisol has been cast as a modern health villain, seeking to slowly destroy you. But it’s actually a critical hormone – one of a few hormones your body can’t live without.

This is because cortisol affects almost every cell in the body and helps to regulate many essential aspects of physiology, including circadian rhythm, metabolism and immune function.

Importantly, how cortisol affects you is governed........

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