Of course it is (my roommate and I set up two hammocks in our dorm room between the wall studs) however the article suggests that simple rocking (not necessarily 'hammocks') is the key. And doing that is easier, in that you need only put your bed on a platform that can rock. (baby cradles have rounded ends sometimes for that).

How about sleeping on a water bed? Is that enough motion?

Mechanically pushing a waterbed would also be easier than making a bed rockable.

Sure.

I live in a very old house that is made of brick, so I couldn't really mount mine directly to the walls (I could, but I'd rather not anchor things into the brick on a house I don't own [it's a rental]).

I bought a hammock stand for $100 and it fits in my rather small bedroom just fine.

Wait, there are hammock stands? Thank you. Purchasing one right away.