There is actually a theory about this, that surprisingly is called " Idle Theory" ;~)
It basically states the following:
"Central to Idle Theory is a physical understanding of life as alternating between two states: busy and idle. While busy, a living creature works to maintain itself. While idle, it is either inactive or engaged in some non-maintenance activity. Depending upon their physical constitution and the environment in which they find themselves, all living creatures operate somewhere on a scale which extends from being nearly continuously busy at one extreme, to being nearly continuously idle at the other extreme. That is, some creatures must work very hard to stay alive, and others hardly at all. Those creatures which, even working continuously, are unable to maintain themselves, disintegrate and die."
Here is a link to the whole thing, enjoy and post back any thoughts.
Bollux! here's the link
www.idlex.freeserve.co.uk/index.html