I know that sleep is important, and on weeks, that I consistently get enough sleep I feel my best. The problem is sometimes I wake in the middle of the night and can not go back to sleep for hours. I know that insomnia in general is a somewhat common problem. I do not want to take medication, but want my sleep to improve. Any suggestions would be helpful.
Sleep Hygiene. Learn it, try it, and see if it resolves your issue.
I've answered this similar question before.
Insomnia has different causes. The most common, outside of poor sleep hygiene, is anxiety or depression. That's something else to consider.
I recommend seeing your doctor in general to discuss it, they can help guide you whether there are any alarm features that might require tests or treatment, like signs of sleep apnea.
Insomnia is extremely rare in indigenous populations, as mentioned in this article where the sleeping habits of 94 members of the Hadza of Tanzania, the San of Namibia and the Tsimané of Bolivia were studied:
Only 1.5 to 2.5 percent of the hunter-gatherers the researchers studied experienced insomnia more than once a year. In comparison, 10 to 30 percent of people in industrial societies report chronic insomnia, the scientists noted. Insomnia was so rare among the San and the Tsimané, they do not have a word for the disorder.
As suggested in the article, one can then try to adopt some of the relevant lifestyle factors that are plausibly involved in sleep. A new finding was the importance of temperature:
The scientists found that the amount of sleep these hunter-gatherers got had less to do with the length of daylight hours than with temperature. These groups sleep an hour more in the winter than they do in the summer. "In natural conditions, humans sleep [more] during a period of declining temperature," Siegel said. "In contrast, in most modern settings, while we may turn the temperature down at night, it is not declining." In other words, modern life has "almost completely eliminated a major sleep regulator," he said.
Another thing that is mentioned in the article is that these indigenous people sleep less than we tend to do:
Investigations showed that these traditional peoples slept slightly less than 6.5 hours a night on average. In comparison, people in industrial societies usually average seven to eight hours per night.
This combined with the fact that these people get a lot more exercise than most of us get radically changes the balance between sleep and daytime exertion. And the diet has a totally different balance between fats and carbohydrates. As mentioned here:
A high carbohydrate diet of rice, plantain, manioc and corn, with a small amount of wild game and fish – plus around six hours’ exercise every day – has given the Tsimané people of the Bolivian Amazon the healthiest hearts in the world.
Their diet is high in unrefined carbohydrates (72%) with about 14% protein and it is very low in sugar and in fat – also 14%, which amounts to about 38g of fat a day including 11g of saturated fat.
So, the bigger picture that we don't get if we only study sleep in Western societies, is that the Western lifestyle is not so robust at preventing insomnia compared to indigenous populations. The people who sleep well in Western societies are still just one or two steps away of getting insomnia, while the way indigenous populations live, put them many more steps away from getting insomnia, which makes insomnia far less likely to occur there, so much so that their languages don't have a word for it:
The San and Tsimané languages have no word for insomnia, and when researchers tried to explain it to them, “they still don’t seem to quite understand,” Siegel says.
which really emphasizes the point that insomnia just doesn't happen there, otherwise the people there would be able to understand it from their own personal experience. From my personal experience, I think that sleep time and exercise may be the most important factor. I run every day for about one hour (and quite fast with my heart rate at about 150 bpm), and I sleep on average slightly less than 7 hours a day. When I was younger I slept for 8 hours and I didn't exercise anywhere near my current level. I did have sleeping problems far more frequently than I have today. So, to me at least, this seems to be a a problem that's caused by the body getting way too much rest and way too little exertion.