Suppose that you also want to sleep better on the long term. Then that may require some lifestyle changes like exercising more. If waking up much earlier than usual and feeling that you just can't sleep more happens quite frequently, then you need to weigh your options such that sticking to your new routine is going to work the best. The problem with getting more exercise is that while sleep is known to be affected by exercise, it's not easy to get to sleep better by exercising more. You need to continue to exercise for a while to reap the benefits for sleep:
But people with insomnia and other sleep disturbances tend to be “neurologically different,” Dr. Baron said. “They have what we characterize as a hyper-arousal of the stress system,” she said. A single bout of exercise on any given day “is probably not enough to overcome that arousal,” she explained. It could potentially even exacerbate it, since exercise is itself a physical stressor.
Eventually, however, if the exercise program is maintained, Dr. Baron said, the workouts seem to start muting a person’s stress response. Her or his underlying physiological arousal is dialed down enough for sleep to arrive more readily, as it did in the 2010 experiment.
We may get a better insight into insomnia by looking at populations were insomnia is rare. It turns out that many indigenous populations don't get the amount of sleep that is conventionally recommended, but they don't suffer from insomnia anywhere near the levels that's considered to be normal in Western societies. As pointed out here:
Though the San, Tsimane, and Hadza often average less than seven hours of sleep, they seem to be getting enough sleep. They seldom nap, and they don’t have trouble dozing off. The San and Tsimane 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.
The Tsimane get far more exercise than most Westerners do. We can read here:
The Tsimane get a ton of exercise, Gurven says, but it's not really intense exercise. "I think there's a general stereotype that if you're a hunter-gatherer and farmer, that you're exercising vigorously every day, like the equivalent of running a marathon, and that's not the case," Gurven says. "It's really just that they're not sedentary."
Instead the Tsimanes do a lot of walking — about 7 1/2 miles each day. And they're active for more than 90 percent of daylight hours. In contrast, Americans spend about half their waking hours sitting down.
And they eat far less fat than we do:
When you hear "hunter-gatherer," people often think of the meat-packed paleodiet. But the Tsimane diet couldn't be further from that. More than 70 percent of their calories come from carbohydrates — ones that are packed with fiber, such as corn, cassava and plantains. The other 30 percent of the calories are split evenly between protein and fat.
So, by changing your lifestyle by getting more exercise, eating healthier and getting a larger fraction of your calories from whole grain carbs, and by not focusing too much on getting 8 hours of sleep (6.5 hours may be enough), you'll likely end up sleeping better.