Given the circumstances, mostly the timing of the events and the external pressures on him to address some big stressors on a given schedule, I guessed that stress was a key contributor in his case. Doctors seemed to want my friend to focus on that aspect.
This particular friend tends to keep things bottled up, and then grows more emotional as events arrive and progress. It's hard to watch, and I've tried to approach the _topic_ of approaching it with him, with little luck. But it has been a good lesson to me: Even if you think you are OK and life is great, continue venting information about stressors regularly. Personally I regularly word-dump into a journal or into my phone for health purposes. My journaling template has evolved a lot over the years and it's still one of my top tools for moderating stress. The stress will always be there, but it seems that, perhaps depending on circumstances and individual psychology, one can do _enough_ of this kind of work to avoid some major stress-related health issues.
An example paper you can read if you are curious:
The most interesting part, for me, was that while I was in hospital I was visited by a guy I'd met for the first time the previous day, during the lost 36 hours. I instantly remembered his name but was also quite sure I'd never seen him before. That was weird.
But then I thought about zolpidem, which I take every day. I've pretty much gotten used to the idea that I won't remember much of anything after it takes effect, until it wears off, perhaps four hours later.
I always lock computer screens, before taking it.