It would be good to have more data on this. If it’s true for a lot of people it tells you something about what PEM actually is.
When you exert past a certain point the body shifts how it’s functioning, metabolic state, immune recruitment, whatever the mechanism is. Say that shift is the PEM trigger, and where it sits is set by your baseline. Then there’s two ways PEM could work.
Option 1. Going into state 2 releases something, call it X. X kicks off a cascade with its own shelf life, e.g. 4 days. State 2 itself isn’t sticky, drop your exertion and you’re back in state 1. So what you’re feeling is X doing its thing, not the state you’re in. Your exertional function is back to baseline, you just feel terrible because a process got started. Resting doesn’t shorten it because the thing you’d be resting isn’t what’s driving the symptoms anymore. All rest does is stop you releasing X again. That’s the sunburn version.
Option 2. PEM is state 2. You drift out of it rather than switch out, symptoms follow that drift, and how fast depends on how little you do. Your exertional function is actually changed for the whole crash and rest works directly.
So basically: does exertion start a separate process, or is your exertional function itself different until PEM calms down.
A week and a half ago, I woke up in PEM, and decided to try my new strategy of doing nothing. For five straight days, 16 hours a day, I lay as still as possible with an eye mask on, briefly using my phone only once every 10 minutes.
I managed to avoid the intolerable deep muscular leg pain that has crept into my PEM in recent episodes. However, I would not say that the duration of my PEM was significantly reduced.
Also, this episode was more concussed/cognitive/microglial than normal, so perhaps I was not due for muscle pain anyway.
My current suspicion is that my post exertional malaise is like a sunburn: the length of time to heal is preprogrammed, and the only thing that matters is not going back out into the sun and making it worse. Doing nothing is a good heuristic for not overexerting, but it is itself a form of torture through ennui.
In future episodes, I will try to land somewhere in the middle between boredom and overexertion and see if anything changes.