Does sound travel better at night?

My speakers sound better at night ;-) Is there any science behind this?
No,No,it's definetly the light.Make sure you have all lights of in the house,and I have found it makes much difference with the curtains closed. I left one open once and could not understand why the sound had not improved that evening,then I noticed a window blind was left open and emitting a small amount of light from the moon I think. I closed the blind and immediately the sonics changed. Now I have come to believe the moonlight is much better than say streetlight,but I much prefer no light at all. But it's all in the light man!
Only if your Clever lil Clock is set to "PM" not "AM" in which case it will sound better in the morning.
I have to poke fun at these subjects to keep my sanity. I most definitely believe their is a profound difference most evenings,and I do not drink or use any uncontrolled substances anymore. It may be a combination of things. I read in a forum somewhere that radio stations are required to power down at a certain time in the evening also,which could play a role. I also noticed recently during the day when it was rainy out that my system sounded better,but it is almost every evening that I can tell the biggest difference. I would like to say it has nothing to do with the mind playing tricks with different mood-etc.,but the mind does cause us to believe some crazy things I believe.Sometimes I come to bed late and the wife asks me what I was doing,I respond the stereo was doing it again to me. It could quite frankly be a certain time when the body releases a certain chemical that happens at the end of the day that actually allows the brain to perceive our sound differently.I don't really want to believe that,but in reality it actually makes the most sense to me. I recently was talking to a well respected man in audio regarding this and he told me he could not critically listen to audio within two hours after eating,that after a meal it destroyed his ability to enjoy the music.Whatever the cause or rationale is,it is not slight. I am far from having a golden ear,and would like to tell you I am borderline deaf,but the night hearing thing is a real one for me also.I really want to blame it on the grunge in the power,and possibly a few combinations as listed in other posts,but seriously believe we create many of these things in our heads. I mean in the evening is usually when we decide ok it's time to listen to the stereo. We put the other thoughts,worrys,distractions aside and then,it's the magic evening thing happening again. I think it may be like the person that is blind,is the hearing really better or is the hearing just used more proficiently? Can we actually perceive the sound we want to hear if we are up tight,hungry,have things on our minds,are distracted in so many other ways?I mean the guy that is blind is no longer distracted by the vision of different things,so does he hear better now? Maybe some people can deal with the distractions and still hear what they hear when not distracted. Does this better sounding in the evening thing happen because we subconsiously set ourselves up for it?Whatever the reason it is usually like switching a light bulb on for me when it happens.
I agree with the cleaner AC, but I do not think that it plays such a big part.

Less distraction, both visual and sonics, better concentration on the sound ''images'' as it takes up your whole space, and a certain release from the tension of the work day. In complete darkness, it ''sounds'' even better too.