Nisha got spayed at 6 months; I think the spay is harder on dogs than a neuter. My dog slept the rest of the night, and was back to her old self again! It was SOOOO hard to keep her still! We majorly stocked up on bones to give her something to do! A very short, slow paced walk calmed her down somewhat.
Make sure your boy doesn't mess with his stitches; make sure his wound stays healthy looking (no pus, inflammation, ect.). If he does mess with his wounds get an E collar (cone).
Don't worry, he will be acting his crazy self very shortly