I'm a teacher teaching young children & I can honestly say the only children who are tired in school are those that go to bed late. The children are very honest when we ask them. Primary aged children should be in bed by 9 at the latest. Many children in my class have an afternoon nap as well. Yes it is air conditioned in the building, but how about break times, lunch hours & outside sports? Children need to run off their energy they can't always be cooped up in the building. Kids adapt to routines very quickly & soon get used to getting up.