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Why do you get brain fog around your period – and what can you do about it?

Experts use the term brain fog to describe a range of temporary ‘cognitive difficulties’, such as trouble focussing, forgetfulness and mild confusion. Brain fog isn’t a medical diagnosis; rather, it’s a symptom associated with a slew of health conditions, including pregnancy, depression, long Covid and, yes, PMS.

The research on PMS-related brain fog is limited, but anecdotally, going through it can be a slog, says Dr Jennifer Roelands, an ob-gyn who specialises in holistic medicine. For example, mental cloudiness and impaired concentration may hurt your performance at work, and research suggests PMS symptoms, including cognitive ones such as confusion, can also impact personal relationships.

Why might menstruation trigger brain fog? I’ve always chalked premenstrual brain fog up to hormonal fluctuations that occur during my cycle. I thought the mental sludge had something to do with cyclical changes in oestrogen and progesterone. That’s possibly not too far off, according to Dr Roelands.

Menstruation can cause all sorts of drastic and rapid hormonal changes associated with an array of symptoms (a.k.a. PMS). Oestrogen and progesterone also play a role in brain function and cognition, but how, specifically, changes in those hormones may directly contribute to brain fog is somewhat unclear, says Dr Cheruba Prabakar, ob-gyn and chief medical advisor for wellness- ingredient company Purissima.

The evidence has been mixed: a small 2017 study concluded there’s no relationship between brain fog and the hormonal changes that take place leading up to menstruation, while a 2020 analysis suggests it’s too early to declare, either way, if and how menstrual-related hormone changes impact cognitive functioning.

Though the research on PMS and brain fog is inconclusive, many reproductive health specialists, including those talked to for this story, say that, anecdotally, people commonly report experiencing brain fog before and during menstruation.

The theory, according to Dr Roelands and Dr Prabakar: the mentally fuzzy feeling is probably due to significant changes in hormones, neurotransmitters and insulin levels that happen during your menstrual cycle.

Research shows oestrogen and progesterone influence neurotransmitters such as dopamine and serotonin that deal with executive functions (a group of complex cognitive abilities that includes working memory and problem-solving).

Studies have also linked low oestrogen levels to cognitive impairment and higher oestrogen levels to improvements in memory and learning. There are oestrogen receptors all over the brain, says Dr Roelands, so it makes sense why your cognitive function is affected by the oestrogen dip that happens during PMS. Experts also know cognitive issues are common in menopausal people with chronically low oestrogen levels.

Insulin levels also go a bit haywire during your period, and the increased insulin resistance – which occurs when your body has a harder time using glucose (blood sugar) for energy – that can result from that fluctuation may impact brain function and memory too, Dr Roelands says. Another theory is that anaemia – a lack of red blood cells in the body that can occur with heavy menstrual bleeding – can contribute to cognitive issues during PMS, including brain fog and fatigue, she adds.

Of course, PMS symptoms vary from person to person. Some people experience overwhelming brain fog during menstruation, while others remain clear-headed.

Genetics, certain health conditions and psychological issues, among other factors, can influence the types and intensity of symptoms people experience around their period, according to Dr Prabakar.


There’s no quick fix to prevent or end brain fog before or during your period – but there are some ways to make it less disruptive and uncomfortable.

Get your heart rate up

Research suggests regular exercise might help lift the fog. Exercise balances out insulin levels and encourages blood flow to the brain, says Dr Roelands, which helps boost memory, attention and information processing, making it a potentially effective way to counteract brain fog.

Prioritise sleep

If you’re not getting enough high-quality sleep around your period – which, for most adults, is seven to nine hours per night – your brain fog will probably get that much worse. Sleep lets your brain rest and recuperate, says Dr Roelands, which helps it function better the next day. Sometimes, PMS keeps you awake at night – do what you can to give yourself enough time in bed and to create a restful environment, but don’t stress if you don’t get the deep sleep you want.

Track your brain fog – and plan around it

It might help to use a period tracking app or journal to record when you tend to experience your heaviest brain fog, So you can try to take it a bit easier on those hazy days – by, say, rescheduling meetings or cancelling social plans. It's unfair, but despite what our patriarchal society may suggest, it’s not as if brain fog makes people completely useless during their periods. Dr Prabakar recommends focusing on all the things you can do to improve your cognition around your period – such as moving your body and resting when you can – while also accepting that you may not feel 100% at the time, and that’s perfectly OK.

This article was originally published in our April/May ‘Wellness’ Issue. Get your digital copy here.

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