i think what graham said about plenty of exercise, if its possible could dad take him a long walk before his bed time tire him out, it might go a long way to helping with the problem
My in laws pick my son up and take him to the park whenever I've been at work so he's actually worn out when he gets home. I just dunno why he still gets up at night. Probably just a habit that's hard to break.
''The grass may be greener on the other side of the fence but there still gonna be on it''