I am not sure what is going on but maybe you could try upping the temps? I have 2 Hyla Cinerea as well and they seem to like the temps between 75-78 during the day and 70-72 at night. You should try to get a hygrometer to keep track of the humidity. I keep the humidity for my frogs at 60%. The humidity is probably low in there and that could be why he sleeps so close to the water. As for the sleeping spread out, I have never heard of that before.