Then CFS seems more appropriate than PEM which is one symptom.How long after the exertion is the exacerbation supposed to occur so that it would be clear that it is cause and effect and it is not necessary to look for other mechanisms or environmental factors or even reaction to chemicals in the body?(I suspect that the higher levels of hormones in the middle and the end of my cycle adversely affect my liver and my symptoms,also exposure to chemicals such as freshly painted spaces cause symptoms.I have read though that some ME sufferers felt better while pregnant so hormones are not an issue for everyone).Are there consistent patterns of exacerbation including timing when you exert yourself?
The timing of exacerbation seems to differ from person to person and it also seems to depend on the severity of illness. Nobody is saying that exposure to chemicals or menstrual cycle can't adversely affect symptoms. But not everyone with this illness reports sensitivities to chemicals or hormones whereas pretty much everyone reports being made sicker by exertion, whether physical or cognitive, which is why PEM is emphasised as a hallmark symptom and why people are trying to figure out what is wrong with the metabolism, the nervous system, the immune system etc. which may be causing these symptoms.