Computer programming requires concentration. The more the concentration, the better the programming. Especially when all the corner cases are being thought of. There are many things to consider. The world of coding is a world of it's own. There are many issues in a multiprocessing mind. Missing one issue could mess up everything. Good programmers don't make mistakes. Hence a time is needed when the best concentration can occur. Usually that means either at night or early in the morning. When the world is not paying attention, the geek goes nuts.