Moonlights are mainly for looks, though if timed properly can give the effect of a lunar period which may induce spawning behaviour by some animals.

well, i set up my timer that at 10Am the sun light will go on until 2 pm, then moon light will go on for 2 hours, then the sun light will turn back on at 4:00 pm until 10 pm. Moon light for another 2 hours then shut off. is that ok.