Spending at least some time outside, part of it in the direct sunlight if possible. IMO it's what our bodies need to stay in the right balance.

Since I'm doing this at least 3/4 of a year (winters are bleak here), the nights I have trouble sleeping are ultra rare. Like a few days in a year. And I'm a night owl, staying late, waking up late, sleeping in the daylight with no blinds on, no screen hygiene at all... none.

Also watch your food habits, heavy and spicey meals consumed late in the day or just before you go to sleep makes for shallow sleep that easily gets disrupted by even a small noise. The same applies to alcohol.