they come out more often when the light is off because they are nocturnal. Regulating a light schedule is good for them, IMO. As for me, I don't use a light because my pad does all the work and the temp in my house. The pad goes from high in the day to low at night. Hydra always come out at night when the house lights go off, IN FACT, i see her coming out now as I type. lol, shes going to have a nightly soak which she does every night, hence the name hydra.