Subject: Do beta fish sleep?

I'm asking this question because I own a male beta fish, I know that they 
breathe from the surface of the water, but I was wondering if they "sleep" too. 
I am just wondering to make sure that he  is not sick since when he appears to 
be "sleeping" he sort of tilts on his side and looks like he's dead. Then he 
spurts up to the surface to get air and then settles back sideways on the 
bottom.

Re: Do beta fish sleep?