This is the most important question here. I hope OP has been able to address the original cause of the insomnia, lest it happen again.

Not fully, but I strongly suspect it had a lot to do with the building I work in. My building has no windows. My lab simulates space, so it is a big room that is painted black. Daylight Savings had just stopped, so I was getting an hour of sunlight driving in to work, no sunlight during the day, and leaving after it got dark. I think my circadian rhythms were completed screwed up.

Once you have insomnia for a few weeks it tends to be self-reinforcing. I didn't get adequate medical care during the first few weeks, when it was acute, so it became chronic. I tried, but the doctor wrote me a half-strength prescription for Ambien, and that was all. It didn't work.

Holy crap you were living in constant darkness. Of course you had sleep issues. Did you ever try light exposure?

Yes, of course. I got a sunlight lamp and put it over my monitor. I actually went so far as sitting outside in the evening for an hour, every day. I also tried taking melatonin.

But the thing with insomnia is that it is self-reinforcing. You get conditioned to lying in bed awake, and that's what your brain then expects to do when you go to bed. And then you get anxious about it, which makes it worse. Once you have it, removing the original cause doesn't solve the problem.

In my defense, I worked under these conditions for five years before it became an issue.

You may be interested in light therapy. Special lights for home that mimic sunlight to keep your body in sync, commonly used in northern regions (so I’ve been told).