I think it has to do with what I would call "social pressure". During daytime you have to be ready for a phone / doorbell to ring, a package to be delivered, a

I think it has to do with what I would call "social pressure". During daytime you have to be ready for a phone / doorbell to ring, a package to be delivered, a package by a neighbor who isn't there being brought to you, an e-mail reaching you, which demands attention, et cetera. It's louder outside. In front of your house kids might play, a dog might bark, traffic is heavier, gardening work is going on,... it feels like a world for extroverts and there is the risk of something demanding your immediate attention while you don't feel like it. There is a "societal" pressure on you to be functioning. And at night, it's the opposite. You can finally relax, focus, you know nothing of that will happen. You feel safe knowing that people around you are sleeping. No one expects anything from you during these hours, because it's the designated time for sleep. What you do now is outside of anyone's expectations, it's your time, your time alone. No commitments, freedom, and focus. So I wonder if night owls are predominantly introverts with some form of social anxiety (whether they realize it or not) and I certainly think there's a large overlap there. I'm speculating, and I am sure it's not true for plenty of people, but it certainly describes me.