I have done all of these for a long time but still find myself waking up earlier as I get older despite no changes to going to bed.
A friend let me in on the real secret: "I've never slept better in my life than I have since retiring. I get up when I want, and I feel no need to maximize my evenings with late nights because i have my actual days."
In addition to the aforementioned items, I've recently accidentally discovered that I sleep way better with earplugs. Silicon ones (they require some know-how when it comes to putting them in properly, which is mostly a process of trial and error) work best for me, because of their comfort and decent sound insulation. I'm apparently sensitive to all the small noises around me (refrigerator, random street sounds, etc).
Another thing that helped me is reducing my water intake (this might vary a lot per person). I suspect I had a form of electrolyte imbalance, because I've been drinking a lot of water, but still felt thirsty quite often. I've learned that balance is key when it comes to hydration, so now I drink a bit less of fluids but as a result feel overall a lot better. I also try to include more of magnesium and potassium rich foods in my diet.
A friend let me in on the real secret: "I've never slept better in my life than I have since retiring. I get up when I want, and I feel no need to maximize my evenings with late nights because i have my actual days."