Cycle syncing has the potential to change lives

Adapting to hormonal fluctuations throughout the menstrual cycle could be a secret weapon in the fight against breast cancer

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Cycle syncing is having 'a moment.' The practice, which involves women adjusting their habits to align with their menstrual cycle, is all over the digital realm.

Menstrual tracking apps - Clue and Flo are just two examples of the many available - are popular. Downloaded to phones, smartwatches and other wearable tech, they're currently used by an estimated 50 million people. Most women use them to track their periods and understand their cycles. On social media, however, cycle syncing is touted by influencers as a means to enhance fitness, help you lose weight and even boost your creativity.

There's scant evidence to back those claims, however. Research published this year from McMaster University, in Canada, for example, found no link between synchronising menstruation phases and exercise routines with the body's ability to build muscle and strength. It hasn't stopped #cyclesyncing from notching up more than 500 million views on TikTok, but it has drawn attention away from another application for cycle syncing: making drugs and medical tests work better.

For drugs to be authorised for use, they have to first be tested in clinical trials. Before the 1990s, however, women were largely excluded from these trials because, it was thought, their fluctuating hormones would cloud the results. The female body was considered too complex and variable, and so most of the studies were done on men. Even female animals were often omitted from laboratory research for the same reasons.

This has changed now, but the effects of the menstrual cycle on drug response remain murky. It’s known, for example, that certain painkillers, such as morphine, are more or less effective at different points in the cycle. Beyond that though, little is known.