This is a much more common problem than even physicians are aware of. Childhood ADHD and behavioral problems can be caused by Sleep Apnea. Even if your children are examined by and ENT or Pediatritian, most just want to medicate your child. Insist that they do a Sleep Study (PSG) and tell them you want their tonsils and adenoids removed.
Do your research before you take them to the doctor. If your child snores, the odds are they have sleep apnea.