I never even realised this was one of the benefits, but come to think of it now you've said it I do remember my left arm near enough falling asleep on a long journey along the West coast of Australia after a few hours in an automatic with cruise control and an arm wrest![]()
I've actually been known to turn them on with my right hand if I'm being especially lazy!

(Althought this probably means more effort!)
Seems to only ever be when the girlfriend is in the car with me though, which leads to lots of "tut"s and the shaking of her head 
