When my little guy was around 3 and had a hard time sleeping, I remember going into his room and asking him why he wasn't asleep. He said something about being too excited remembering his day, or just not being tired or looking forward to something that was going to happen the next day. Then I said; " Oh, silly me, I forgot to give you your 'sleeping dust'. I'd lightly brush his eyelids closed 3 or 4 times, and sofly touch his cheeks and nose with my fingertips, like I was gently typing on his face, and let him know that now that he had sleeping dust, he'd drift off to sleep in no time, but ONLY if he kept his eyes closed.
This worked really well. Then one night, after he had called for me from his bedroom that he couldn't sleep and needed more sleeping dust, I let him know that it was he too had the power to administer sleeping dust and that if he brushed his face the way I did and kept his eyes shut that it would work.. I was still happy to get him started as I put him to bed, but if he needed a little extra, he could do it himself.
This also worked well.
Then came the 'monster' issue. The night I was first informed that sleeping dust was not working as well has he had hoped because there was a persistant monster that was trying to get into his dreams, I exclaimed 'silly me, I forgot to give you 'unicorn power''. Everyone one knows that monsters are afraid of unicorns, and unicorns can only do good, so if a monster starts bothering you, just call for the unicorn and it will scare the monster away. So, when he went to bed, I would brush his eyelids and tell him I'm give him 'sleeping dust WITH unicorn power'.
He's seven now and when I'm tucking him in I rarely say the phrase, but I can see that as soon as I brush his face, he's calm and not worried about a thing. He might not go to sleep right away (often he needs to read stories to his stuffed animals so that they can fall asleep too) but he doesn't have a worry to his name.
Hope this helps.
Keith.