Taking that saying to heart - 'don't tell me the problem, tell me the solution' here's a message to anyone who has a late-to-bed light sleeping 3 year old:
Up till new year, it was a miracle if I could get my toddler to sleep before 9.00 any night. Then he started a new nursery - hours from 9.30 to 3.00 - on the first day he arrived home and fell asleep at 5.30 and was totally unrousable.
Thinking it was due to first day fatigue, I put him to bed and expected him to get up later - he didn't, though briefly woke up for a quick drink around midnight. The next few days were the same - suddenly, literally overnight, his sleep routine changed from owl to lark. We are now moderationg this routine and he has been going to bed betweeen 6.30 and 8.00. - waking up around 7.00 am. Perfect for me, and all it took was a strenuous nursery day to change the habit of a year or two. I'm crossing my fingers the new sleep routine remains. It feels so wierd to have no toddler running around at 8.30 pm every night, wierd but nice!!
Anyway, if you have a late sleeping toddler, hang in there and wait for nursery to begin - hopefully like me you will see a significant change.