I have so many years of not-sleeping behind me, I'm practically a professional. I used to think the Department of Defense should be studying me. The more exhausted I was, the less able to sleep I became. I finally found the answer to this lifelong problem at drgominak.com but I still do these things below too. Maybe someday I'll be a 'sleep anywhere, anyhow' person, but probably not.
1. If you let your insomnia bother you, it gets worse. Even when I feel like hell in the morning, by the end of the day, I don't feel too bad. So, when I get up, I tell myself “Yesterday was fine, and today is going to be fine, too, even if I didn't get enough sleep.” Because it usually is.
2. Avoid eating sugar, simple carbs like pasta or potatoes etc. in the evening. For some people, these can cause sleepiness, but as we age our bodies have a harder time dealing with them, especially at the end of the day, and they keep some people awake. Even innocent things like fruit can do this because it contains sugar in the form of fructose.
3. Supplements that might help: lemon balm extract, cinnamon, turmeric, piperine (Indian plant called Pippali) mixed with some fat/oil taken about 2 hours before bed. This has helped me but not consistently. About ½ tsp of each powder, in hot water or milk, all together. It doesn't taste good, but you can put a microdot of honey in there. Some people find Magnesium chelate or glycinate helpful but it gives me diarrhea.
4. Keep a regular schedule. Go to bed about the same time every night, and get up about the same time every morning, even if you didn't sleep enough. Even if you're exhausted, don't go to bed at 8pm but stay up until your bedtime. Think about it. If you usually only manage 5 or 6 hours of sleep, going to bed at 10 and falling asleep will have you waking up at 4am. So you'll still have a frustrating night. Find something to do that will keep you awake until bedtime. I've found needlepoint to be the right amount of mindlessness and engagement.
5. Disconnect from all screens and devices at least an hour (preferably 2) before bedtime. The blue light they emit STOPS melatonin (sleep hormone) production. If you wake up at night, DON'T go look at a screen! If you must look at a screen, use blue-light-blocking glasses. They're available from lowbluelights.com
6. Some LEDs have a lot of blue wavelengths, and do the same thing. You can change the bulb near your bed to a yellow bug light, which mimics candlelight, and is more restful.
7. Speaking of light in the bedroom, that's a definite sleep-killer! The new super-bright street lights are a real pain. When I used to travel a lot, I sometimes carried black bin bags and tape to darken the rooms. Finally solved this problem by wrapping a long, soft scarf around my head and over my eyes. Now it's another signal to my body that it's sleepy time.
8. Some people find a warm bath helpful. It raises your core temperature and as it falls after the bath it's supposed to mimic what your body temp does in response to your circadian rhythm. This has never worked for me. Speaking of circadian rhythm, allow at least 12 hours between your last meal of the day, and the first. And when you get up in the morning, expose yourself to bright light for at least 20 minutes. It helps get your body clock on track.
9. You can try melatonin supplements, but the dosage is tricky. Some research shows that the therapeutic dose is .25mg. It is often sold in 1 or 3mg tablets, and so it's hard to get a small enough dose. Liquid melatonin can be given in smaller quantities. Personally, I've never found it helpful, but some people do. It's a hormone.
I see now that my body was physiologically unable to sleep normally. It didn't have enough of what it needed to create adequate neurotransmitters for sleep, which explains why all those supposedly sleep-inducing teas, herbs, soundtracks and so on were not effective. Drgominak.com really saved me!