My 6 yr old son has been going to sleep at 600 everynite for a week is that normal

Is he complaining that he's feeling sick at all?

It very well could be that he's going through a growth spurt. I remember those times with my kids, they slept a lot more during that time.

When in doubt, it's never a bad idea to speak to your family doctor.

Did school just begin? My kindergarteners are exhausted by lunchtime and their parents say they go to bed very early.