As nice a theory as it is, more recent studies do suggest that it’s more coincidence than anything else. Lakhani suggests: “If you are living with several other women, and given the duration of a menstrual cycle, the probability of some of you having your period at the same time is quite high.”

Menstrual cycle coach Roxy King agrees. “Overall, scientific studies have not been able to prove that menstruators’ cycles do sync, and if they do, it’s been put down to coincidence and confirmation bias,” she says.

In fact, what the studies do show clearly, is that women want it to be true. In one study, menstrual synchrony was noted as a positive as it creates a collective experience and offers an opportunity to feel part of a group, which is a primal human instinct. Let’s face it, when we’re feeling bloated, crampy and irritable, what we really want is someone to agree and empathise with us, not tell us how great they’re doing.

Menstrual cycling syncing: here’s why you end up coming on your period just after your housemate