I believe at least a few or more hours of darkness is a very good thing. Nothing wrong with evening blues but let the tank sleep while you do. That said I doubt blue lights will do any real harm.
At night, sundown, I run my blues 10% over white. This fades to blue only at 8pm and then lowers to around 10% blue only at 9-11pm. Then off, dark till 5am. This of course isn't a rule. Just my preference.... used to play with them a lot but eventually you settle into a natural rhythm.
I'm guessing you've got a white and a blue separately controlled with either off or on? My advice would be to have whatever you like until you usually hit the sack then have them off totally. I'm tempted to say it depends on what you have in the tank... but it actually doesn't. These creatures live in the same rhythm as we do. Dark at night is best but a little blue in the eve don't hurt none. Don't worry about it. Keep it simple.
You can put your lights on timers. I usally turn on the blues about a hour before the main lights come on. I will run the main lights about eight hours and then the blues for a hour and then all lights out untill the next day. Fish like to sleep as we do.