If he is sleeping during the day then he is sick. Chameleons do not sleep during the day. Be careful posting pictures if you do not know exactly where they came from and the story behind them
its normal for them to be awake during the day, and to sleep at night, going to sleep about when the sun goes down (which your lights should be similar to).
so if the sun goes down and your lights turn off around at 7 and he goes to sleep at 7, that's good.
Chameleons dont always turn black when stressed contrary to popular belief. A lot of the times they can show their most impressive colors when stressed. This is why it is irritating when someone says their cham is happy to be handled all the time because the colors are always so bright or flashy. Not the truth.