Women make fewer mistakes and have better mental agility while on their period despite feeling worse than at any other time during their menstrual cycle, research suggests. The research, conducted by the UCL Institute of Sport, Exercise and Health (ISEH), found that women’s reaction times, accuracy and attention to detail were heightened while menstruating, challenging current hypotheses regarding how women perform in sports during their period. The study, published in the journal Neuropsychologia, involved the analysis of data from 241 participants (including 96 who were male and 47 women who were not regularly menstruating due to their contraception, for comparative purposes) completing a battery of cognitive tests, two weeks apart, and the collection of reaction time and error data. Participants also recorded their moods and filled in a questionnaire regarding their symptoms, while period-tracking apps were used to estimate which phase of their cycle the participants were in when they took the tests. The tests covered reaction times, attention, ability to relate to visual information, and anticipation of when something might happen, and were designed to mimic mental processes during sports. There was no group difference in reaction times and accuracy between the male and female participants, but the women who regularly menstruated were found to have performed better during their period compared with any other phase of their menstrual cycle, displaying faster reaction times and making fewer errors. This is despite the participants reporting feeling worse during their period, and believing this to have negatively affected their performances. Dr Flaminia Ronca, the lead author of the study, from UCL Division of Surgery and Interventional Science and ISEH, said finding that women performed better during their period was “surprising”, and that this could change the way female athletes’ performance was considered in relation to their menstrual cycle. She added: “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 Megan Lowery, an author of the study from UCL Surgery and Interventional Science and ISEH, 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. “Though there’s a lot more research needed in this area, these findings are an important first step towards understanding how women’s cognition affects their athletic performance at different points during their cycle, which will hopefully facilitate positive conversations between coaches and athletes around performance and wellbeing.” Prof Paul Burgess, a senior author of the study from UCL’s Institute of Cognitive Neuroscience, said that the idea for the study came from speaking to female footballers and their coaches. He said: “We created bespoke cognitive tests to try to mimic the demands made upon the brain at the points in the game where they were telling us that injuries and problems of timing occur at certain times of the menstrual cycle. “As suggested by what the soccer players had told us, the data suggested that women who menstruate – whether they are athletes or not – do tend to vary in their performance at certain stages of the cycle. As a neuroscientist, I am amazed that we don’t already know more about this, and hope that our study will help motivate increasing interest in this vital aspect of sports medicine.”