As is the case with most women’s health issues, there is limited research into what causes period brain fog, but experts believe it has something to do with the hormonal changes that happen during the pre-menstrual period and the relationship these hormones have with vital neurotransmitters in the brain.

“The decline in hormones before the period – mainly progesterone and oestrogen – can lead to brain fog symptoms,” Dr Roked explains. “This decline shouldn’t necessarily cause long-term issues, but the temporary reduction in progesterone and oestrogen can affect our focus and concentration, as both hormones can impact neurotransmitters and areas in the brain involved in memory and learning.”

It’s worth noting that there’s little conclusive evidence to show that these hormonal variations drive period brain fog or that period brain fog is related to our hormones in any way. For example, a small 2017 study concluded that there was “no consistent association” between oestrogen and progesterone levels and cognitive function. But that doesn’t mean there isn’t some kind of link.

“Why do I get brain fog in the week before my period?” A hormone doctor explains