Likewise. I've always observed 1) closer fidelity to what the sun's doing than to what the indoor lights are doing (even though we don't have very good window, and I would think the sun's influence would be minimal) and 2) heading for bed before light's out (sun and/or indoor). In our Michigan winters, when it's dark by 5, the chameleon may well have settled down for the night by 3:30. I've observed this with two animals, a panther and a Jackson's.
My interpretation, for what it's worth, is that they head for bed early to be sure of making it before it gets dark. Chameleons have effectively no night vision (they have a very high density of cones, the color sensing cells of the eye, but no rods, which are the low-light cells and predominate in nocturnal animals like cats), and they want to be sure of getting home in plenty of time. But that's just speculation.