I've noticed that I often feel better before a crash or PEM/PENE sets in. It will go something like this: I overdo something i.e. 20 minutes in a quite café with my boyfriend. I get the initial overload "I have to get out of here"-feeling, with feeling lightheaded, foggy, nauseas and generally bad. I get home and sit/lay down and I feel better than before I went out for anything from 20 minutes to a few hours. Then PEM slowly sets in, and I crash. Sometimes it doesn't propely set in before the next day or night. What causes these minutes/hours of feeling better before the PEM? Is it better bloodcirculation, adrenaline rush or something else? Does anybody have an easy and understandable way of explaining this?