787 Windows Dark For Whole Flight - Please Hear Me Out

I recently flew from PHL-DOH, departing Philadelphia at 7pm or so. 14.5 hours. I totally respect having the cabin dark for the benefit of those who want to sleep, but I find it strange that the cabin needed to be dark for all (except the last 30 minutes) of 14 hours of flight. Wouldn't it be sensible to remove the darkness around sunrise or after say 10 hours of darkness? We humans tend to sleep 8 hours if we are lucky, so I don't understand the purpose of a darkened cabin for 14+. Thoughts?