We all know that men’s hormones fluctuate in a 24-hour timeframe, which corresponds quite neatly to the solar cycle. Women’s hormones work in a longer pattern (roughly 28 days), with four phases, just like the lunar cycle.

Many moons ago, long before pinging period tracker apps came to be, the menstruating woman had to rely on more natural ways to fathom out when her period was due. So the moon, with its 29.5 day cycle of waning and waxing, seemed a good benchmark. New Moon? Period about to start. Full moon? Ovulation alert! Simple really. Even the word menstruation comes from the Greek word ‘mene’, meaning, you guessed it, moon.

A study published in the January 2021 issue of Science Advances magazine hypothesises that our monthly ebbs and flows may indeed have been synchronous with the moon during ancient times. But as artificial light took over our towns and cities, all this changed. (In our oceans, far away from the bright night lights, the amount of moonlight over the ocean is still strongly linked to spawning and breeding.)

There’s no denying that these days not everyone starts their period at the same time – can you even imagine? – but that doesn’t stop the link between periods and the moon persisting. Because even if it doesn’t happen every month, your menstrual cycle will intermittently synch.

Lunar devotees believe there are two cycles that women fall into, or just either side of. The white moon cycle – the most common – is linked to the new moon, meaning you get your period around this time, and ovulate around full moon. Because this mirrors the traditional rhythms of the moon, a woman with a white moon cycle is said to be in the ‘Mother’ stage of life, either planning or nurturing a family. The red moon cycle, where you get your period around the full moon, is known as the wise woman’s cycle, because in ancient times these women were the teachers and the healers – those who sought to empower other women around them.

A 2016 study of 7.5 million cycles by period tracker app Clue debunked the theory of lunar influence entirely, concluding that period start dates fell randomly throughout the month, regardless of the lunar phase. The takeaway being (obvs) that you need a period tracker app.

So which camp are you in? Even if you think it’s bunkum, there’s something comforting in looking up at the full moon and knowing that many millions of women around the world are feeling pretty similar to the way you are right now.