They're doing it to annoy you.
There was one summer where I stayed at school, living in the dorms. Typically, each dorm will have 2 or 3 floors open, and repairs are done in the rest of the building. They weren't supposed to start until 8am, but they always started by 6am or so. I was living on the top floor of the building, and one morning I was awakened at 6:30 by footsteps overhead... they were fixing the roof. (6:30 is not as bad as 4, but still...)
When it snowed, snow plows would be deployed around campus, and snow removal would start as soon as the snow stopped - day or night. So you'd be woken up by the intermittent
beep beep beep of a snow plow in reverse. On the one hand, I was glad the snow was removed and the paths were (reasonably) safe by the time I had to go to class; on the other hand, I wanted to sleep at night!