Agree totally! I just could not believe there was no setting for bedtime.
I just turned 70. I get up at 07:30 and usually go to bed close to 23:30. I have no problems going to sleep, but do agree that late night screen time probably influences how long it takes me to fall asleep.
I have a friend who is even older than I am and has never slept more than 4 hours a night (difficult to keep up with him intellectually! he has so much more time than I to read and think). He would be totally dissatisfied with f.lux.
So, when are we getting a setting for how many hours we are normally active and awake, or bedtime or something similar.
There is a setting for sleeping in on the weekend, which I never do. Anyway: sleeping in on weekends is equivalent to providing yourself with one or more hours of jetlag.
But I do want a setting for bedtime.