Elementary school kids should go to school earlier than middle school!
While it is true that, yes, Kinder gardeners get naps and half days, I believe that it essential to note that you have not taken into consideration one essential fact to early childhood development:
It is a biological fact that the younger an individual is, the more sleep is needed to maintain a healthy mind. When someone sleeps, there is a certain key moment in deep sleep in which the individual dreams, called rapid eye movement sleep (REM sleep). In such a sleep, the eyes will move at random and the muscles will become paralyzed. At this point in sleep, this is when the individual is at the high point of whatever their dreaming. This is, by far, the MOST important stage of sleep. If someone doesn't get enough of this stage of sleeping, very serious sideffects can occur such as 'microsleeps', which is essentially people falling asleep and passing out no matter what they're doing, and only 72 hours of constant awakeness one can experience very potent and severe hollucinations, sometimes even causing serious mental trauma