After I read what you had written, I recalled, after so many years, that my strict nanny was like that. Except lunch was a bit later

I went to the wikipedia article about Circadian rhythm. They have an interesting graphic (you need to click on it to enlarge) that shows the clock with best time for stuff and with certain events, e.g. when melatonin production stops and starts. I cannot go running at 5PM (spent after work) when it is optimum for cardiovascular efficiency , but I can begin work promptly by 10AM when it is highest alertness time. So I was happy that I can time at least something to those rhythms.

I THINK THE BIGGEST problem is that with this illness, it is so darn difficult to keep the rhythm yet for health it is so widely recommended to stick to it.