I'm a teacher — this sentence reminds me of the times that I used to be so devoted that I would sleep in the school overnight so I could create lesson materials in the evening and get ready quicker in the mornings.
Our language school was located inside an office building that anybody could enter, so it was pretty scary to stay there at night. A couple of times I had bad dreams where there were lots of people talking, then I woke up to find the lights in the complex had been turned on by somebody, but there was always nobody to be found.
A couple of times when I could snatch a free couple of hours, I would watch a horror movie on the big screens! It made for a truly spooky and horrifying experience. They were interesting times!
I'm not Indonesian but from what I have learned you need to say "malam hari". It would be the same if you were saying Our school is noisy in the afternoon - "Sekolah kami ramai di siang hari".