After a visit to my chiropractor today, I found myself wondering about the effects of hammocks on the body. Now, don't get me wrong: I love my hammocks and often do wake up feeling better than when I sleep in a bed. My quandary, however, is that most of the purported benefits I've read of are either vague or highly anecdotal, but when I think about it logically, I'm not sure why sleeping with a curved back and rounded shoulders could be good for you.

Could anyone point me to some research or give a reasoned explanation of the actual physical benefits of a hammock? What does it do to the curvature of the spine and posture? What effect does the position have on the upper back, lower back, shoulders, etc?