The results showed there was no difference in reaction times and accuracy between men and women .
Period-tracking apps were used to estimate which phase of their cycle women were in when they took the tests.
Women make fewer mistakes while on their periods, despite feeling less capable at this time of the month, research suggests.
Experts discovered that women experience fluctuations in mental agility throughout their menstrual cycle, with faster responses and fewer mistakes when they are on their periods.
A team from University College London (UCL) and the Institute of Sport, Exercise and Health (ISEH) studied a group of 241 men and women, who completed online tests and whose mood was recorded, together with their symptoms.
The tests – which covered reaction times, attention, ability to relate to visual information, and anticipation of when something might happen – were carried out twice, 14 days apart.
Period-tracking apps were also used to estimate which phase of their cycle women were in when they took the tests.
The results showed there was no difference in reaction times and accuracy between men and women, but the findings for women were particularly interesting.
They were found to perform better during their periods compared with during any other phase of their cycle, with faster reaction times and fewer errors.
In contrast, women showed slower reaction times and poorer timing anticipation when they were between ovulation and menstruation (luteal phase), alongside more errors around ovulation.
This was despite women reporting feeling worse on their periods, including lower mood and suffering physical symptoms.
Writing in the journal Neuropsychologia, the researchers said “a significant proportion of females felt that their symptoms were negatively affecting their cognitive performance during menstruation on testing day, which was incongruent with their actual performance.”
The tests in the study were designed to mimic mental processes that are typical in team sports
The tests in the study were designed to mimic mental processes that are typical in team sports (Alamy/PA).
The tests in the study were designed to mimic mental processes that are typical in team sports.
In one test, participants were shown smiling or winking faces and asked to press the space bar only when they saw a smiley face. This tested inhibition, attention, reaction time and accuracy.
In another, people were asked to identify mirror images in a 3D rotation task, while a further test asked them to click when two moving balls collided on screen.
The results showed that, for women on their periods, timing was on average 10 milliseconds (12%) more accurate in the moving balls task, and they pressed the space bar at the wrong time 25% less in the inhibition task.
In contrast, women’s reaction times were slower during the luteal phase of their cycle – an average of 10-20 milliseconds slower compared with being in any other phase.
They did not make more errors in this phase, however.
The authors noted that previous sports medicine research has shown that women seem to be at greater risk of sport-related injury during their luteal phase.
They suggested that fluctuations in timing could mean the difference between an injury or not.
Dr Flaminia Ronca, first author of the study from UCL and ISEH, said: “What is surprising is that the participants’ performance was better when they were on their period, which challenges what women, and perhaps society more generally, assume about their abilities at this particular time of the month.
“I hope that this will provide the basis for positive conversations between coaches and athletes about perceptions and performance: how we feel doesn’t always reflect how we perform.”
Dr Ronca told the PA news agency the tests measured timing and other processes, but the study did not measure IQ or intelligence.
She said it could not be suggested that women were more or less intelligent at any given phase of their cycle, adding “we are purely talking about reaction times and timing of movements”.
Dr Megan Lowery, who also worked on the study, said: “There’s lots of anecdotal evidence from women that they might feel clumsy just before ovulation, for example, which is supported by our findings here.
“My hope is that if women understand how their brains and bodies change during the month, it will help them to adapt.”
