I'm going *slightly* off topic here, but I do believe a good night's sleep is the core of having a happy and healthy child. I know when I don't get enough sleep I feel awful and my whole day goes sour. Imagine being a sleep deprived child who has very little control over their day. Parents are likely going to face behavior problems all day, including mealtime behavior.
How much sleep does a child need? Parents magazine has a great chart that shows the amount needed by age. Grayson is 6 years old and sleeps from 8 pm - 7 am. He literally falls asleep within 5 minutes of going to bed and wakes up on his own naturally around 7 am, so I know 11 hours is what his body needs. Harper is 3 (almost 4) and goes to bed at 8 pm when Grayson does but doesn't fall asleep until usually 9 pm (she "reads" and plays quietly with her stuffed animals until she falls asleep) and wakes up around 7:30. She still takes a nap on most days and goes to sleep earlier on days she doesn't, so she averages about 11-12 hours of sleep a night.
I know a lot of parents who have trouble getting their kids to go to bed and trouble waking them up in the morning. I believe strongly in a consistent bedtime/sleep routine to solve these problems. Good sleep behavior is learned, and you make the rules! Don't forget - a child needs far more sleep than an adult. When the sleep is good, behavior is going to improve and mealtime struggles will usually be less.