I do not have classic POTs as I do not in the very short term have any noticeable problems standing upright within the constraints of my current ME symptoms, other than when my ME is more marked requiring a stick for balance. However, I am wondering if being upright, either standing or sitting is for me more exhausting than you would expect from the physical exertion. Being upright seems to be a more significant factor in limiting the amount of time I have out of bed each day rather than other aspects of exertion. For example sitting upright and talking to someone is as tiring as doing housework for the same period of time, however the talking is not the limiting factor as when I can only tolerate say half an hour sitting talking, I could tolerate an hour or so talking with someone whilst lying down. Similarly I can spend significantly more time using my iPad lying down than I can using a computer sitting up. Obviously sitting uses additional energy, but for me sitting at the computer is as tiring as gardening for the same amount of time. I have not for some time kept a detailed activity record. In the past it has been very useful in identifying problem foods (eg gluten intolerance) and helping me understand my boom and bust cycles and the implications of post exertional malaise, but given I currently only have two or three hours a day in total not lying down it feels that the essentials of daily living are more of a priority. However this means I can not be certain if my subjective impression that just being upright is as tiring as undertaking physical activity for the same amount of time is accurate. Does anyone else have a similar experience? Does any of the published literature on orthostatic intolerance or POTs look at it as a continuum rather than an all or nothing phenomenon? Is there such a thing as mild orthostatic intolerance?