When in Your Menstrual Cycle Do You Think Fastest?

Imagine your brain reacting faster at one point in your menstrual cycle than another.

A team at University College London (UCL) tracked participants across four phases of the menstrual cycle and found that cognitive performance peaked at ovulation.

However, physical activity level had an even larger effect on reaction speed and error rates.

Why the menstrual cycle matters for cognition

Women are still under-represented in sport and exercise science studies. Across six major journals, just 6% of studies include female-only participants. Many sport‒science studies have excluded women or failed to track their menstrual cycle because hormone fluctuations are seen as a “confounding” factor, leaving gaps in what we know about how the menstrual cycle affects performance.

It is widely believed that changing levels of estrogen and progesterone across the menstrual cycle affect mood, cognition, reaction time and injury risk. Some studies report slower reaction times or reduced focus in the mid-luteal phase – when progesterone is high – or more errors just after menstruation, yet other studies find little or no effect. Athletes often feel that their performance declines during menstruation, despite scarce empirical support for that view. Evidence from injury research suggests the risk of anterior cruciate ligament tears or concussion may vary across the cycle, possibly linked to changes in biomechanics or neuromotor control.

The new study aimed to test directly how cognitive performance, mood and symptoms change across the menstrual cycle. It also examined whether being more physically active altered those fluctuations.

Cognition varies across the menstrual cycle

The UCL team recruited 54 people aged 18–40 years who had regular, natural menstrual cycles and were not using hormonal contraception. Each participant was placed in one of four groups based on activity level: inactive, recreationally active, club competitors and elite athletes.

They completed short online tests four times in a single menstrual cycle – on the first day of menstruation, two days after bleeding stopped (late follicular), the day ovulation was confirmed by urinary testing and around one week later in the mid-luteal phase. The tests measured reaction time, sustained attention, inhibition and spatial anticipation – quick-thinking skills used in team sports and daily movement. Participants also rated their mood and recorded symptoms such as cramps, fatigue and low energy.

Cognitive performance peaked at ovulation, when estrogen levels rise and progesterone remains low. Reaction times were ~30 milliseconds faster and accuracy improved. Responses slowed in the mid-luteal phase and participants made more errors in the late-follicular phase.

“This is the first time we’ve directly measured ovulation in this context and we found that cognitive performance was at its best during this phase,” said lead author Dr. Flaminia Ronca, an associate professor at UCL.

The elite athlete group showed larger swings in performance across phases, hinting that intense training may amplify menstrual-cycle effects on cognition.

“But the really interesting finding for me is that the difference between those who were active and inactive was much greater at ~70 milliseconds, which is enough time for the brain to register a stimulus and initiate a voluntary reaction, and is therefore far more meaningful for everyday life,” Ronca added.

Inactive women also made roughly three times as many impulsive errors as active participants.

Mood patterns followed the hormones. Energy was highest at ovulation and lowest during menstruation, but these changes didn’t affect performance.

What this means beyond the menstrual cycle

For athletes, even a 20-millisecond difference in reaction time can matter. “At the elite level, this could make the difference between sustaining a serious injury in a collision or not,” said Ronca.

For everyone else, the results underline a simpler point: staying active benefits the brain far more than menstrual timing hinders it.

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“This shows the importance of incorporating some form of recreational physical activity into our lives. It doesn’t have to be that intense or competitive to make a difference – and crucially, it’s something that we can control,” Ronca added.

The study also helps dismantle a persistent myth – that menstruation makes women less focused or capable. Over half of the participants believed they performed worse during their period, yet their results showed no drop in attention or reaction time.

“It’s great to see that, while participants assumed that they were performing worse during menstruation, the findings don’t demonstrate any detriment to cognition. If anything, cognitive performance peaked during ovulation,” said co-author Evelyn Watson, a research assistant at UCL. “This is a positive outcome that we hope can help develop a new narrative in female health and performance.”

However, hormone levels were inferred from ovulation kits, not directly measured and each person was tracked for only one cycle. The cognitive tests were also completed online, meaning the setting couldn’t be controlled.

Future work should incorporate hormonal sampling and brain-imaging data to clarify why cognition shifts throughout the cycle. Comparing women who use hormonal contraception and studying specific sports could offer deeper insights.

“Working exercise into our day doesn’t need to be difficult. Some of our previous studies have shown that 15 minutes of moderate activity is enough to boost our mood and cognitive performance, which is equivalent to taking a brisk walk around the block or cycling to the shops,” concluded Ronca.

Reference: Ronca F, Watson E, Metcalf I, Tari B. Menstrual cycle and athletic status interact to influence symptoms, mood, and cognition in females. Sports Med - Open. 2025;11(1):104. doi: 10.1186/s40798-025-00924-8

This article is a rework of a press release issued by University College London. Material has been edited for length and content.