Yeah, I have been trying to do that for many years, because obviously poor sleep has plenty of bad outcomes, not only long-term but also including immediately obvious ones.

But for some of us, it's hard. I have taken measures like exercising, having dinner earlier, trying to read for a while before going to bed, etc. and they do help somewhat, but the truth is I seem to be too sensitive to stress. When a backlog of tasks accumulates (which, in my job, is most of the time) I start ruminating about work in bed, sometimes this gets compounded by gas and reflux (I once thought this was about food, but no, I have long found out that it's totally about stress, if I'm on holiday I can eat like a horse and never get gas and if I'm stressed I can get it from pretty much anything) and there goes my night's sleep.

My work is pretty stressful (and hard to reduce the workload) but I don't think I can just blame the job, as this happens even when the backlog isn't such a huge deal objectively speaking, and I can handle it. But it seems that I'm just bad at disconnecting from things. In fact for example if I have a morning flight the next day I always sleep like crap, not because I have any fear of flying at all, but my mind is just not at rest thinking what if the alarm clocks fail (which never happens), etc. I know it won't happen, but the thought keeps me awake anyway.

People with treatment-resistant primary insomnia should go ahead and make their peace. If CBT-i, calming exercises, or the small stable of medications (all of modest efficacy and some themselves implicated in dementia among other risks) don't work for you, then there's not much that can be done.

We don't have very powerful tools to help with sleep, which is a damned shame seeing as insomnia is a consequence or cause of so many problems.