‘Stress hormone’ cortisol is blamed for infertility, but major new study hints that could be wrong

engin akyurt/Unsplash 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 by its pattern of release: the ups and downs.

Social media will have you believe a cortisol “spike” is always bad news.

But precisely timed increases in cortisol are not necessarily bad – they may be exactly the signal your body needs to start one of its physiological processes, such as regulating your sleep.

The long shadow of early cortisol research Discovered less than 100 years ago , cortisol is a relative newcomer to biology.

At the time, researchers had no reliable way to measure natural cortisol levels in blood.