According to the charity PoTS UK, postural tachycardia syndrome is “an abnormality of the functioning of the autonomic nervous system”. Broken down, it means the position of the body (“postural”) causes a faster-than-normal heart rate (“tachycardia”) alongside a combination of other symptoms.

Dr Lesley Kavi, visiting professor at the University of Birmingham, has been the charity’s chair since 2017. She explains: “When a healthy person stands up, blood vessels narrow and heart rate increases slightly to maintain blood supply to heart and brain. In PoTS, this automatic adjustment to upright posture is not working correctly, resulting in an excessive rise in heart rate, increased norepinephrine (a chemical produced by our fight or flight response) in the blood and altered blood flow to the brain.”

PoTS: postural tachycardia syndrome affects 5 times more women than men, but what exactly is it?