E.E.
If this is something that has not happened in 6 months, then I would take him to the doctor to be sure he does not have an infection. If he is healthy, then you can think about waking him up about 1/2 hour before it usually happens and have him go to the bathroom. Then if he is still tired, he can go back to bed. Also try to limit fluids about 2 hours before bedtime.