Last week I spent time with a 8 year old who had trouble getting to sleep. We made a poster together listing all the things he could try to get to sleep (eg slow breathing, reading, thinking about his favourite things, listening to his ipod etc).
Having it by his bed for him to choose strategies from has helped a lot, according to his mum today. Giving him some control over his sleep also made him feel good about himself. Over the long run, this will be more successful than just telling him what to do.
Helping your child draw up a list like this might be worth a try if you have a mildly insomniac child in your house.
These two cuties in the video below on the other hand, don't need any help at all!!