No, sideways is not a comparative form of an adjective.
positive
The degree of comparison for "sideways" is the positive degree, as it simply describes the manner in which some people sleep. It is not being compared to anything else in this sentence.
can you walk sideways
He stepped sideways. Crabs walk sideways and lobsters walk straight.
You can make the view sideways by putting the Game Camera sideways on something.
move the cyclic sideways
There is no comparative of get.
It is automatically played sideways...
A sideways pass is called a lateral.
The Sideways Door was created in 2006.
South of Sideways was created in 2003.
Sideways was released on 10/22/2004.