I'm interested to hear if people think being a university academic is compatible with mild/moderate ME/CFS and, if so, any ideas for managing things. My son is looking at the possibility of starting a PhD next year.
Doctoral study was a good fit for me whilst mild but I think its going to be highly variable, dependent on institution and subject domain. I was fortunate that my engineering group was not at a very competitive university, it was also largely commercial and always needed "students" to do the work. The group paid all university fees and doctoral students were given a tax-free stipend that you could live off.
We'd work collaboratively on large group contracts for 4-5 years and try to feed in our own research interests during that time. Eventually the Uni would get fed up and force us to write up a thesis, hacking together our parts of that prior work, then graduate. Usually there was a post-doc research position (leading the next group project) available after that. Those that didn't eventually leave to take a job in industry but wanted more seniority would begin to supervise their own PhD students and/or take up lecturing. Optional work was often available too: teaching workshops, marking or exam monitoring.
I "studied" part-time, usually about 15-20 hours per week in the lab and perhaps a further 5 hrs at home. Many of the "full-time" post-docs just rocked up at 10am and left at 4pm... retained bad habits from undergrad days and because of that they had to crunch hard at deadlines, but that could be avoided. It was all very flexible, too flexible really! When my health failed and I ended up more moderate-severe the Uni were exceptionally supportive and had no problem parking my progress for 18M until I was a little better and able to drag it over the finish line. In the end it took me 8 years to get the PhD, including that 18M break + crawling at the end. Honestly, I would say it requires more willpower and stubbornness than intelligence to complete!
I think it would be a different experience outside of that big research group, especially if at a competitive uni, with a fixed length & funded project and/or a more modern PhD pathway - i.e. one that includes taught/assessed courses like you'd see at graduate level. Higher workload and higher day-to-day stress probably.
I'm quite fond of a description given by someone that compared completing an MD to a PhD, after having done both. They suggested both were hard and like swimming 10K, except for the MD you swam in a warm pool, with coaches on the side-lines cheering you and a visible lap counter to rely on. The PhD was more like being dropped in the cold ocean, on your own, then told to swim blindly to where you think the land is... and invent a new stroke whilst you're at it!