How do mandarin's sleep? FYI he was just sleeping :o)

[fishoholic]

My mandarin usually sleeps in the sand, but this morning he was half floating half swimming near the top of the tank and seemed oblivious to everything, Steve cuped his hand right around him and he didn't notice, also the light from the flashlight didn't phase him. Sort of freaked me out because at first I thought he was dead, but his gills were still moving and his side fins were moving, however his body was sort of curved in a U shape and he wasn't moving his tail.

Then I was worried maybe he was sick or something, but when I came back to look into the tank again (to see if he was still floating at the top) there was no sign of him. I'm hoping he was just alseep and that he's not sick and that he woke up and is now hidding in the sand or rocks.

Anyone ever heard of or seen their mandarin sleep like that?