“Low blues at night” is a relative term. A few 3w blue LEDS over a big tank for “moon light” probably won’t hurt anything (even all night). The most popular programs these days have a brief moonlight period before and after the photoperiod as others have stated.
I use reds for night viewing. It doesn’t seem to affect or bother anything (once again, dim red light, not 200w of red LED). It appears that lots of creatures don’t see that spectrum as well as humans and so they exhibit their nocturnal behavior and I can still watch- most shrimp, bristle worms, Eunice worms (how I caught him), spider or arrow crabs, squirrel fish, etc come out and corals switch to “feed mode” instead of photosy and it’s like a different tank.
I’m sure you posted the type of lights you have by now…