It has been a long week. The start of formal education at school signals many things; long days, a more firm routine, a P.E. kit and book bag, new friends and old ones, new teachers, formal learning and some learning with play. It's more time away from Mummy and Daddy but more time with friends.
It means at short nap on a Saturday because even though you stopped napping about 18 months ago the week was just so tiring and exciting and different and Saturday night means seeing the family so you want to stay up a bit later.