A new scientific study has revealed that a woman’s brain actually changes during her menstrual cycle, not just in one small area, but across the entire brain.
The study, led by Dr Elizabeth Rizor and Dr Viktoriya Babenko from the University of California, Santa Barbara, followed 30 women through different stages of their monthly cycle to understand how hormones affect the brain.
Using MRI scans, the researchers took images of the women’s brains during three important stages: menstruation, ovulation, and the mid-luteal phase. What they found shocked even them. As hormone levels rise and fall, both the grey matter (which aids in thinking and decision-making) and the white matter (which facilitates communication within the brain) change in size and structure. Even the brain fluid that protects the brain also moves and changes during the cycle.
The study showed that just before ovulation, when hormones such as estrogen and luteinising hormone increase, the brain’s white matter becomes more active, meaning information moves faster. Another hormone, FSH (follicle-stimulating hormone), helps make the grey matter thicker, thereby improving brain performance. After ovulation, progesterone causes brain tissue to become denser, while reducing brain fluid, indicating that the brain physically adjusts throughout the menstrual cycle.
Experts say this finding changes the way people should think about menstruation. This is not just about cramps or mood swings. It also involves profound physical changes in the brain itself. Despite menstruation being a normal experience for half of the world’s population, scientists say it has been poorly studied, especially in terms of how it affects brain function.
In the past, most studies only focused on how hormones influence mood or behaviour. However, this new research is the first to demonstrate that the entire brain structure changes in response to hormonal rhythms.
Doctors believe this discovery is critical because it explains why some women feel mental fog, stress, or anxiety at certain times in their cycle. It may also help medical experts understand why some mental health issues, like depression and anxiety, are linked to hormonal changes.
Another global study, published in 2024, also confirmed that every stage of the menstrual cycle affects the brain differently, depending on a woman’s age and hormone balance.
Scientists say this discovery could alter the world’s perspective on women’s health. For years, menstruation has been viewed only as a reproductive matter, affecting the womb and ovaries. However, research now shows that it extends even further; it also occurs within the brain. In simple terms, menstruation does not just affect the body; it also rewires the brain.
