Ok, this is sort of off the wall, and we only had mixed-results ourselves. When ds8 was about 6 we got him a bed-tent. Basically it's a little pop up tent which slips over the bed mattress and encloses the child, he really liked it for adventure-appeal and coziness but I am not sure he got to sleep a lot sooner, but they are recommended for this reason (brains not shutting off for some kids).
Now, we let him read for a while, this seems to do the trick.
Good luck! smile

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