A 24 hr saliva cortisol test to see what his cortisol cycle might be a good idea. High cortisol in the late evening contributes to insomnia. Keeping a food journal to see if any foods and/or preservatives and artificial flavorings and colors are affecting his sleep patterns. Maybe doing a hair analysis for heavy metals and a parasite cleanse with Clarkia, or Paragone for kids or Humaworm for kids.
What is his diet like?
A long soak in very warm baths might help tire him out.