I think people are built differently and what works for some people doesn't work for others. I know people who can't function without a hearty breakfast. For me, eating soon after I get up makes me feel sick. I feel best if I don't eat for several hours after I get up.

For sleeping, I think the most important thing is routine / habit. If your body recognizes that you're in the routine you do before bed, it knows what comes next. What that routine is can differ from person to person.