Help for 3 year old boy

Hello,

I would appreciate any help for my young nephew. For the past few weeks, he has started waking up any time from 11pm - 2 am. He goes straight to sleep when he is put down at 7, but when he wakes, he is fully awake and ready to play. He might then go to sleep at 4:30.

He has had dreams of monsters coming to get him for the past few weeks as well. He has also started to ignore some of the things I say, which is a recent development - he can switch from being such a good polite boy to running around throwing things. When like this, he laughs in not a nice way, almost a mocking laugh.

He has also started to go to the toilet when he is asleep, mostly loosening of the bowels (which might be because his bowels relax when he is asleep?).

We are trying to get him to do pre school work, and he has a tendency to angry with himself if he can't do it first time, and will say that he is tired.

He will also bring up an injury (like a scraped knee) that happened a few hours ago and then cry, like it just happened. He will also look at me as if it was somehow my fault.

I hope this information will be useful in determining a remedy; any help would be appreciated, as I really need to get some sleep as well!

Thank you.