I’m not sure why you say that.
If one takes care of themselves in terms of diet and exercise, good sleep should be a thing for most of their life.
I’m in my 50s, and I sleep about as well as I did in my 20s (possibly better).
Being exhausted when I go to bed helps and I ride a bike to get that, but having the time to get my milage high enough isn’t always possible.
Good point.
I probably should have written something like “…diet, exercise, and mental health”.