When I got CFS in 2015 I was living in Tucson then moved to Southern Utah, and am currently living in Phoenix. Although I'm still debilitated by this illness I have had more energy here in Phoenix than either Tucson or Utah. Have always wondered why I feel better here than in the other 2 places, but wrote wro elevation as I had assumed Tucson and Phoenix were close in that regard. Evidently, that is not the case. Phoenix is about 1,000 ft above sea level, whereas Tucson is 2,389 ft and the city I lived in/will be moving back to is 2,860 ft above sea level. Obviously none are high altitude cities but is the difference enough that someone with ME/CFS would feel more fatigued, sleepy and/or tired with the elevation increase?