I have caught my aros sleeping many times.....
In the morning, when I turn on the room lights, they don't wake up for another 1/2hour. They are still swimming at the surface like normal, but seem to be in a trance....they startle easy at that time....I think they can't see you well, but notice the shadows....you have to approach the tank slowly...
You can place your hand in front of them, and they almost bump into it.....you could also very carefully touch them lightly, and they don't even twitch.
I have also caught them like this in the afternoons.