Glad to see this thread. I finished my PhD in a very writing-heavy discipline before being diagnosed, though in retrospect I’ve had narcolepsy since before I started grad school and maybe since before college as well. I almost didn’t finish my dissertation because of my inability to stay awake while writing, and it was only when I was pretty far into that stage that I began to think my exhaustion was not psychological, laziness, depression, procrastination, anxiety-induced insomnia, etc. etc. Anyway, I only wish I had advice on how to deal with faculty and my grad school’s administration vis-à-vis accommodations and the like. But I can say grad school is definitely not impossible, even though it be would be fair to say I was not – once I hit dissertating – on an accelerated path
I can, however, offer some advice from the perspective of having been a professor for a few years. First of all, when on the job market for academic positions, it’s common to have your advisor explain gaps, blips, or discrepancies in your record in his or her letter of reference. If you have a professor you trust, you may want to ask him or her to address the impact of your condition on your academic performance. I would have taken such a request very seriously from a student who was obviously bright, capable, and motivated, but clearly underperforming (and that’s not hard to see, especially in smaller classes). I also would have worked out with the student the extent to which he or she wanted me to disclose the disability in the letter. And as a general piece of advice about letter-writing, keep in mind that everyone in academia is where they are because someone wrote letters for them, and at pretty much all career levels. So when you’re asking for a letter, you’re not doing anything the person you’re asking hasn’t had to do.
That said, my second piece of advice is if you’re thinking about a PhD, give some serious consideration to the career paths it leads to. I have more or less taken myself out of the tenure-track game because I realized (even before diagnosis) that I would not be able to publish articles and books at the pace the tenure clock required. I have an alt-ac (alternative-academic) job that I really like, that is more or less in my field, and that allows me to produce scholarship at a different pace, but this is pretty rare among those of my grad school peers who did not end up in tenure-track jobs. The academy is going through a crisis at the moment, and good jobs are scarce. I’d tell anyone thinking about a PhD to peruse Inside Higher Ed or the Vitae column of the Chronicle of Higher Education, or just google “adjunct crisis,” in order to make an informed decision about grad school. It may very well be that in environmental science, there are quite a lot of other careers to pursue with a master’s or doctorate, which would be great; just make sure you know what’s on the other side before going in. Good luck!