well honestly, one of my chameleons found a really weird sleeping spot between a pot a plant is in and the corner of the cage with its tail and bottom on the floor of the cage. But you have to judge your chameleons behavior to really determine if there is something going on. My chameleon was acting fine, doing everything normal. just happened to find a weird sleeping spot. The only time I intervine with moving them to a more comfortable spot is my chameleons sometimes will fall asleep hanging upside down. That just kinda freaks me out and I will move them. They don't like it one bit, but IMO its better then them falling from the top and hurting themselves.
If you've noticed a change in behavior I might take your cham to see a vet. Not eating or drinking, weird color stool. lethargic and not moving much. eyes closed during the day. all signs that something could be wrong, accompanied with trying to sleep on the ground.