When their body temp drops and its dark they are a lot less aware. Their brain is cool. Some chams will let themselves fall to the ground if touched while they are asleep...its a defensive tactic to appear more like a dead leaf than an animal. He may well be less aware of being touched, but it may trigger a startle reaction which isn't good. He won't be conscious enough to know YOU are touching him, so sort of wasted effort. Chams usually don't enjoy being touched anyway. With an aggressive cham I find that keeping your activity around the cage to a daily schedule he can expect, hand feeding him (using a cup if he hates hands) will help him accept the fact that you are not a threat but a source of good things. If he feels he can get as high up as possible this can also help him feel a bit more secure around you.