You can tell when a writer is sick because if they are really, truly sick, they not only can't write, but they can't read either.
Imagine being stuck in a hospital bed for 3 days with nothing to do but stare at the wall. Perfect time to read and relax. Except my brain was mush, and the last thing I was capable of was creativity. Pity. I could've read at least one novel, or written a good 5000 words. Instead I lay there (with holes in me that connected to tubes with drips and medication) and did nothing. Well, I have to admit I did "listen" to dozens of conversations. Not eavesdrop, because it wasn't deliberate, but I was in an open ward where the only thing between me and all the others was a curtain. And voices carried quite clearly. Nothing I think I'd ever use in a story or novel, but impressions and emotions, and some funny incidents. Grist to the mill, as a writer friend said to me.
Other unintentional research? I got to ride in an ambulance, and see bunches of trainee doctors trailing around after the surgeon on rounds, just like on TV, and hear lots of medical terminology being used.
I also discovered that when you disappear unexpectedly for three days, all those things you had scheduled are suddenly up in the air. Discussing final editing/proofreading of your new book from your hospital bed is difficult. Deadlines sometimes can't wait.
If you ever have to rush off to hospital (public, not private), don't forget your toothbrush and toothpaste. It's not supplied. Not being able to brush my teeth was horribly disgusting, and it was the first thing I did (twice) when I was finally allowed to come home. And then I went looking for a good book to read.