In other words, if your child can go to bed, fall asleep easily, wake up easily, and not be tired during the day, then
he is getting enough sleep.
Is your child complaining about a bedtime that’s earlier than
his friends’ bedtimes, and saying that everyone else gets to stay up later? Let
him know that every child is different and that this is his bedtime. Tell your
child that you’re keeping his bedtime at the right time for
him because it’s healthy. He’ll feel better during the day if
he sleeps well at night.
Source: www.med.umich.edu