Hi Touie, and yes I have seen bunnies flat out asleep, and dreaming away no doubt :lol:
I think that for most of the time though Bunnies just take short naps and dose on their feet.
As they are prey animals they cannot afford to be sleeping too much, but once they entrust their Mummy or Daddy (of the Human kind) to keep a watchful eye out for them, then House rabbits especially tend to zonk out properly.
I rarely see bunnies outside sleeping for long though....so this is a good reason to bring your bunny into the house, so it can have a proper deep sleep for once :lol: