You will run in to different protocols on the forums. If you follow the Ayurvedic method it is important to do it by 10. Anybody else it probably is not important.
We always, as far as we can, go to sleep at 10 pm. we follow the Ayurvedic method and get up at 5 or 6. Believe it or not we are retired and we get up that early.
We follow Ask Andreas Moritz
It is kind of interesting I use to eat when I got up during the night, but now I know the body is not always processing it and it ferments.
I can't give you the hours, but it is important to sleep between 10 and 2 am.
If you are ever interested in it google Ayurvedic or buy Andreas Moritz
book "Timely secrets etc" http://www.ener-chi.com
If you are interested read the healthinfo, articles, interviews.
Twenty years or so ago I bought the book of Deepak Chopra, that is when I was exposed to Ayurvedic medicine. I also, at that time, visited the institute of Marahishi (sp?) Ayurveda in Lancaster, MA where moviestars Elizabeth Taylor and George Hamilton went too.
Andreas is a vegetarian, but I don't know if all Ayurveda's are that way.