Streaming music sounds better late at night. Is this just me?

My system tends to sound best late at night ~11PM and the very best on Sunday night. I have noticed this for forty years with different systems, in Arizona and Washington. 

OK, is there anything we can do about this? I already have a very good power isolator Torus RM20.

We had few discussions on this subject and so far nobody has been able to pinpoint the reason for improved sound at night.  I suspect that all factors play small role, including electrical grid pollution, reduced AM waves, reduced cellphone traffic etc.  
There will be some noise injected from the Ethernet.  Ethernet has inherent isolation, but nothing is perfect (there are always few pF across).  Perhaps some ethernet filtering might help, but I don't know much about it.  Other than that, usual precautions, like running signal and speaker cables away from (or perpendicular to) power cables, proper grounding and shielding etc.

This has been going on for ages with Radio. Radio always sounds better at night even in the car.

Since the major factor removed is the Sun and another factor added, the Moon, both of these are probably involved by influencing electrical noise.

In hot areas electricity usage rises at night due to aircon so less people using electricity maybe is not a factor.

Late night listening has been a go to listening period for myself on regular occasions.

To sit down without distraction when the body really rewards for being allowed to  relax, is a great time to take part in a self indulgence, these simple pleasures will generate the feel good factor.

How much the system improves as a result of using the system at a time when the ambient is at its most quietest and the impact of the Lower Grid Usage on the system at this time of the evening during the  playback time is an unknown, but the experience being encountered is worthwhile to keep pursuing.