I saw a naturopath on t.v. yesterday who was discussing the advantages of probiotics. He even stated that an unbalance or depletion of healthy bacteria in the intestines can give some kids nightmares and night terrors. Had never heard of this, but I do know that there is a strong relationship between the gut and the brain. (ever get nervous and then have to use the loo?)
Anyway, this may be an area you might want to pursue. My family and I take a probiotic everyday. There are a few different ones that have different bacterium so it might be best to speak to a naturopath for their suggestions.