Biologically, it comes down to two things: the natural rise and fall of women’s hormone levels and our body’s response to heat, which are different to men’s, Dr Arif said.
Women produce less sweat and start sweating at a higher temperature, research – including this 2025 study, external – shows.
This impairs our ability to quickly shed excess heat and makes it harder to judge when our bodies are under burden, simply because we can’t see as much sweat on our skin or clothing.
The same research found, external that women also have a higher core body temperature and body fat percentage than men, which acts like an extra insulating layer.
Now combine this with the natural fluctuations of women’s hormones, which already put our brain’s temperature regulation systems “out of kilter”, according to Dr Arif.
Our levels of oestrogen and progesterone shift most substantially during the menstrual cycle, perimenopause, menopause, pregnancy and while breastfeeding – which can make you less able to regulate your temperature.
All of this is hard work for our cardiovascular systems, especially in hot weather.