Hey, congrats on the ticker LS.
We are another lot here who only found a decent nights sleep in a sposie (actually,most nights it is 2, one on top of the other as he out pees 1 )
We *think* it is the smell. I dont know if he has super reeky pee (I suspect so) but OMG, when you walked into the room after he as been in there for 8 hrs, the smell just assaulted you. So he was fine, up until about 2-3am and then was just awake constantly. Put him in sposies and he sleeps through till 5.30 -6.00.
Some people find the smell of sposies feral, but i guess the evil chemicals in them must do something to neutralise our ponky pee.