If we turn Bob's light off at night (leaving only the purple heat lamp on) and he is not on his log he runs around the bottom of the cage smacking the walls with his nose and his front paws(hands?). If we darken the cage and he is on his log he goes to sleep. Anyone have any idea why he does this?
Even though you are using a purple/black light it still can disturb their sleep. They sleep much better (as you have realized) in total darkness and it is also necessary that it is cooler at night. You don't need any nighttime heating unless the room temp drops below 65 and if it does, then you can use a ceramic heat emitter that gives off heat but no light.