I guess you could read from the chart that it tails off fast but it still says between 6a - 9am is the highest all day. Yes it tails off but I dont read the chart contradicting anything that was said. Its highest in the morning and tails off to nothing but midnight. I did read somewhere, to lazy to go look, that people that work night shift or up during the evening manage to manipulate their circadian rhythm. It definitely was not me. I worked third shift for about a year. About died from no sleep. I think Brian1950 original question was why the Rhumy pushback. I think this is a good explanation but only his DR knows. I say whatever works best. Maybe Brian1950 sleeps all day. I take about an hour nap.