Can a snake close its eyes when it sleeps?

Snakes sleep with their eyes open because they dont have any eyelids. Their eyes are covered by a clear scale called a spectacle. You can see this when your snake sheds its skin. Some scientists believe that snakes went through a period in their evolution when they were underground and lost their eyes compeletly. That may be why snake eyes have a very different structure than any other kind of animal. they dont have eyelids..but they still sleep..you can tell by looking at the eye..if its like a very thin line in the middle..they're asleep.. make sure u wake them up 1st by tapping the cage before picking it up..they get aggresive when u shock them
Because the have no closable eye-lids. They have a clear lens over the eye-ball - called the 'brille'