Peek in on him, if he's sleeping, don't worry about it.
If you think it might be an issue, drape a blanket over the tank once the lights have cooled down. My guys don't care if the lights in the room are off or not, and sleep in a spot that's a little "shady" anyway.
If it would relieve some stress, you can adjust the light timer to go off later, too, as long as you have them turn on later, too.