Susan, if you'd like some personal experience shared by me, I am not a great sleeper in terms of duration. I sleep well enough, just not long enough. And, I seem to drift toward shorter durations over time unless I 'whack it' with a good night or two. I use melatonin and zopiclone sparingly....like about once, maybe twice a week....at most. I tough it out the rest of the time. This way, the two keep their potency for my system to react to. Our bodies are designed to habituate, to adapt, to stressors and other influences (it's formally called the hormetic effect). Our bodies will adapt to drugs the same way, and the drugs soon lose their efficacy. We must increase the dosage or find a substitute that actually does the same thing for us in the way we need it to (those last seven words are important). So, I tough it out for two, three, four nights, and then take the relief. Amazingly, this has worked rather well for me. In fact, I haven't resorted to a zopiclone, usually a 1/4 pill works well enough, for well over a year.

About your overactive brain/imagination (only you know the balance that exists there between your ears 😉 , I hope you don't need some advice at your stage of life about dealing constructively with real and imagined fears. Leaving aside those imagined, which is a whole nuther problem and way of treating, the real fears must be faced and dealt with with the same determination that you use to tackle spring cleaning; purposefully, determinedly , and ruthlessly. Get them behind you!!