Canis Lupus is by its nature a nocturnal animal. This is an instinctual trait that is shared by wolves, dogs, and other subspecies.
The ancestors of dogs generally would sleep during the day and then get up late in the afternoon once the sun starts to set to begin hunting.
While dogs have generally adapted to human sleeping patterns, it doesn't mean they don't retain that nocturnal trait. My dog (even before he become an "old man") would fall asleep when we left the house and sleep most of the day so he was ready to go when we got home from work. This means he is still awake when we go to bed. Sure, he will follow us to bed, and maybe catch a quick nap, but if any of us wake up in the middle of the night, he is there to greet you.
Fortunately he doesn't make a lot of noise, be he is generally moving about. And the other dogs we've own have shared behavior, but some happen to be more nocturnal than others. Your dog would appear to be one that is very nocturnal and does most of his heavy work after dark.