It is tough isn't it.. I would say he may feel a little insecure about his little world at the moment..

This is what I would do.. I would leave the house lights on ect but lay down with him in his room.. cuddle up and talk about his day.. And when he starts to act up remind him over and over it is bed time. then say Archie it is bed time now.. Lets go to sleep.. It may take a few nights but eventually he will feel secure again ..

I hope you have a good night..