[jareds]

I'm totally blind and have what I call no usable vision. I can see light if it's bright or the sun is shining. I can't tell anything about the environment from my vision though other then if there is bright light or not. Anecdotally from talking to other blind people the ability to see light helps set your body clock. Although I keep a fairly normally sleep schedule I know blind people who have no light perception and have a lot harder time keeping a normal schedule with out medicine.