Reception year, to me, does not matter a jot if summer births, too young to me.
I do agree Norah and it is a worry but, as reception year is fairly play-based and a transition between play group/nursery, I think on reflection it is better to start then than to risk missing that year at school and have to start in Year 1. It all depends on the child too, of course as loopylou says.
DGS age 2, could not sleep at all when they had nap time at nursery. I think he was the only child who could not drop off to sleep.
Doesn't take after me, I like a nap too unless I am out for the day!