Discriminating Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and comorbid conditions using metabolomics in UK Biobank, 2024, Huang et al

So do you think the nervousness precipitated the PEM or did the nervousness create the insomnia and being awake for so long precipitated the PEM?

 

Not speaking for Kitty, but I also get insomnia the night after a day of intense overexertion. Might take like 3-4 hours longer to fall asleep. This is before any real PEM. It just feels kind of like trying to sleep after drinking a coffee.

I guess it's possible less or worse sleep can at least partly cause PEM.

 

If we were to say PEM is caused by energy being expended beyond a certain level then this would make sense.

Patients discuss limiting exertion but what they refer to is limiting exertion they control, most energy is used outside of our control to keep us functioning day-to day. Beyond that, it sounds like sometimes things happen to patients that are beyond their control and burn more energy. Being awake burns more energy than being a sleep, feeling wired or anxious burns more energy than feeling relaxed, etc.

I suspect PEM is often precipitated by burning energy beyond the patient control. If it is fight-flight then the autonomic measurements like HRV could be useful as a predictor of PEM.

 

I don't think it was a big factor, but feeling a bit nervy for the first half hour would probably use up more capacity than usual.

Most of the overstimulation was caused by being in a busy, noisy environment, working my diaphragm hard to blow a woodwind, tapping my feet to the beat, plus travelling and back. It's always hard to sleep when I've overdone things, but music seems a particularly effective way to trigger the wired-but-tired effect.

Usually I just factor that into my pacing, but this looked like disaster-scale PEM—the sort where the level of lymph gland swelling and sore throat suggested I was in for weeks of feeling terrible. Thankfully it turned out I'd picked up Covid.

This makes sense of the pattern and the experience, but maybe we should be careful about accepting it just because it makes sense. Envisaging PEM in terms of energy might not be helpful; I've started using the word capacity instead, to try and break out of that mindset. (Not very successfully so far, if I'm honest.)

We do feel as if we've run out of something when we trigger PEM, but it may have nothing to do with energy. It could be that it just sets off a signal, in the same way that getting infected with Covid set off a chain of consequences.

Fo what it's worth, the only reliable indicator I've found is an after-the-event one. My overnight resting heart rate goes up noticeably during PEM and illness, and not just for the night when I can't sleep. I don't think it's unusual to see a raised RHR during illness, but it's interesting that it happens with PEM too.

 

Yes agreed. Not stuck to the concept of PEM and energy or capacity. It does seem like the most often discussed connection but best to keep the mind open.