You can try adjusting the sleep times more gradually, for example, cut the nap by 15 minutes and bring bedtime earlier by the say amount. Do that for 3-5 days, then reduce the nap by another 15 and move bedtime up that amount. We have had really good luck with this approach when we needed to adjust the boys' sleep schedules. One thing we have found is that longer night sleep can be more restorative than naps and a shorter sleep at night. At age five, our relatively high sleep needs son was usually out by 7:15 and up by 7. If he was really tired, he might be out by 7 at night. We do pretty short bath and bedtime routines.

Emotions can be felt very deeply at this age, in our experience. What does he say or do about the reasons for his anger?