Have you ever watched an episode of Saturday Night Live in the day time? (The old stuff with Belushi and Aykroyd) It's not funny. Why? Because it was meant to be seen at 11:30 P.M. when people are relaxed and more open to frivolity.
Ever had a really nice bottle of wine with lunch? Good but not great. Same bottle at 9 P.M. dinner is spectacular.
I think our brain is either hard wired by nature or through conditioning to be more relaxed and open to external stimulus at night. We are in the hunter gatherer mode during the day.
There are probably some gear salesmen in here who could attest to this. They play music during the day to sell equipment and it sounds great but at night when they close the doors and put something on the TT for themself s, Bam!
The only exception to this rule is a gorgeous woman. (Or man depending on your gender and personal preference) Our brain will react to that stimulus the same, day or night, and you can still argue that nature hard wired us for that too.