Never had any mental health issues myself, but my dad did have an 'episode' last year, honestly no idea what the proper terminology is!
Think until then it was something I'd always been a bit ignorant of, not really seeing the true extent of things first hand can make it difficult to really understand things sometimes. The change in him was incredibly stark though and really opened my eyes to how it can affect people.
For as long as I can remember my dad had always seemed pretty comfortable with himself, not like one of these people who was always the life and soul of the party but he was sociable with pretty much anyone and just as happy with his own company. Probably a bit of a pessimist and for some reason oddly paranoid about things being locked but otherwise nothing out of the ordinary, just a pretty normal guy with wife, kids, house and a decent job.
Think he was first diagnosed with anxiety, he became really uncomfortable around people especially large groups, and was prescribed some medication. That had the side effect of messing with his sleep and think after a few more trips to the doctors he was diagnosed with some level of depression too, he ended up being signed off from work at that point and was just confined to the house spiraling deeper and deeper. He didn't seem to get any benefit from medication, just side effects like the lack of sleep that made things worse for him. Yet despite that he couldn't get any alternative treatments through the NHS, after a while my nan ended up paying for him to go see someone private and that seemed to get him back on the right track.
Thankfully it was a relatively short lived ordeal for him and seems to be his old self again now, no longer on any medication either as far as I'm aware. Few things really stood out for me in that time though, namely the speed/scale of the change in him and how badly my mom seemed to deal with him whilst he was suffering.
The only thing I can remember happening around the time it started was that he tore a muscle in his calf. We hadn't long returned from my sister's wedding in Cyprus where he'd been playing quite a bit of squash, tennis and swimming with us lot who were all under half his age. He carried on going to play squash with my brother in law afterwards and that's where he had his injury. Obviously I'm no expert in this subject but I've always thought that it might have been the trigger, a sort of realisation he was getting old and becoming more vulnerable, think that then worried him about doing other things he'd never have been concerned about before.
When he first opened up about his troubles to me I found it quite uncomfortable, I'm a bit dead inside and never really been one for any sort of emotional displays. As I was still at my parents at the time, I'd frequently be joined by him at breakfast time and although it was far from the start to the day I wanted before driving over an hour to work, it seemed like he needed to get things off his chest so I always made the time for him. Not sure he got the same patience from my mom very often though, there were several occasions I can remember where I'd overhear her going off on one at him, think once he even questioned if I'd heard them arguing when we had our breakfast chat but I pleaded ignorance. It was clear to me that he wasn't really my dad at that point, not the man I'd grown up knowing anyway, so I had to extend a degree of leeway for this new personality as difficult as it could be sometimes. My mom just seemed to get increasingly frustrated with him through, like this new personality was a choice he was making and he should just snap out of it to avoid the problems it was causing.