The chameleon shouldn't be up at night so it wouldn't do much. Unless you were having humidity issues I guess it could help that. But I would turn it off.
Yup, when I tried to move my veiled in the night she didn't wake up and it gave me quite a scare I turn anything that drips/mists at night because the chameleon doesn't randomly wake up and drink, unlike us . I agree with everybody else on that