This is pretty much the same as I've said before to people regarding my wife. To the DWP, ambulance crew, and others. It's a description that helps give the uninformed a better insight into just how catastrophic the loss of energy is. And that whereas the marathon runner will recover pretty speedily, my wife will likely hit it several times a day, or simply be stuck in that state for ages. And if I'm feeling slightly bitter about it, I suggest they ponder how they might cope with that situation. ETA: And of course for those with severe ME, they are more or less permanently in this state, and some worse.