he may have closed his eyes but not been alseep.
or reflex, bobing the head in many lizards such as the BD's is a way of trying to assert dominance and define teritory.
next would be to display his/her beard.
even with the eyes shut they can detect shadows via a "third eye" this helps them to keep from beeing eaten.
look at the top of the head, betwwen the eyes and you should see a pin-point that looks like a small scale.
that eye can not "see" but can tell if the lights are on or off and if a shadow is cast.
it also plays a role in the BD telling how long the day is and when to "wake up".
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