That sounds similar to the technique referred to as the gravity position... sleep need saver in the forum forum Polyphasic Sleep.
http://www.learningstrategies.com/forum/ubb/Forum4/HTML/000476.html I admit I didn't follow that forum much since I get by on 4 hours sleep a night and once every month or so go 54 to 72 hours without sleep. Don't know why just do. By the same token when I want to sleep I can - the topic wasn't important to me. So can't be sure if that is the same technique.
Alex 
