Actually the title is a bit of a misnomer. My good spells last no more than half a day. While my symptoms tend to fluctuate a little depending on what I'm doing etc most days are just like any other. However, on average three times a year, I suddenly feel better. Not just marginally better but almost 100% well - the way I was pre-ME. These spells are not related to any activity, the weather etc. The way I conceive it is if you think of the various bodily systems as like a long sine wave, dipping above and below optimal, but all out of sync. Inevitably they will all be in phase at at optimal level at some stage. Of course, when this happens I tend to want to do the things everyone else takes for granted and we arrange to go to the cinema, out for a meal or something. Without fail this 'overexcitement' results in a completely sleepless night, as if my brain just can't process all the information, followed the next day by a mighty crash and a further few days before I'm back to my 'normal' routine. As for the bad days they tend to be prompted by more specific things such as doing to much physically or mentally. Apart from the complete mental shutdown I suddenly go from being generally mobile to a bent over, pidgeon toed, limping pseudo-pensioner just about capable of dragging myself to bed. Does any of this sound familiar.