Does he have to pee really bad when he wakes at 4am?
Mine will toss and turn for an hour and then finally wake up and be so scared to get up and go pee if the night light's not on that by the time he does he's fully awake (at 6am).
Is he teething? Is he crashing off a sugar high from a snack before bed? It doesnt even have to be a sugary snack. The body's blood sugar drops something like 4- 6 hours after eating. Try offering a high-protein snack before bed.
That's all my ideas...
