This is another one of those posts where I try to describe some highly subjective symptom in the hopes of improving our understanding of the illness. I think that everyone knows the kind of fatigue where there is an intense fatigue sensation. This is more the kind that you get after sufficiently intense activities or at the end of a day of work. It makes you want to rest. There is another kind which I suspect is much less common and it's the kind of fatigue that makes someone say they have no energy, or more accurately, no energy reserves. Because that is what it feels like: it is an absence of energy reserves. You know in that you're in a state with little stamina and reduced strength. It makes you want to limit and avoid activities that aren't necessary. The second kind seems to be more common with delayed PEM and with disrupted sleep. I am not sure that fatigue is a good name for it. Does any of this make sense?