do snakes sleep?

I've actually stepped on a water snake without it moving. It was definitely alive when I grabbed him... ;)

First off, do snakes sleep? I think no one can know for sure. Maybe if they did some kind of brain scan, but that wouldnt work, for it would surely wake a so called sleeping snake. In all my reading and searching for the answer, all I ever find is, that snakes are close to the ground and have covers that shed to protect their eyes. Yah......
I know that, so answer the question!!! No one can give the answer. For all we know they could be aliens....LOL

Food for thought: http://snakesarelong.blogspot.com/2015/08/do-snakes-sleep.html