I don't know if it's the kind of story shared on that show, but I once had to be wheeled into an ER with hypothermia on a warm day (dry, properly clothed, etc).
Physical stress seems to do it the most. For example, if I get sick or injured (such as have surgery), everything starts to go haywire.
Often it's more random seeming but with less extreme impacts.
But also, as you said, it can be like a battery percentage. Like, I get more and more and more worn down over a handful of hours or days or weeks, and then that causes a bunch of other symptoms. I've learned to pace myself to avoid that.