That's great guys, but you and I both know that being on "call/red alert" doesn't preclude you from sleeping when you want to sleep, does it?!
Sure it limits the radius that you can travel from your home - but it doesn't tie you down completely.
Being locked into a tin capsule, travelling at several hundred miles per hour, several (tens of) thousands of feet...or several miles up, if you prefer......where the O2 level is less than down at S.L., sort of DEMANDS one's attention - if only to monitor that nothing goes wrong..goes wrong...goes wrong.
Lying in bed/dozing at a desk waiting for the 'phone to ring can cause one to snap precariously into reality - but fortunately reality will WAIT for you to adjust to IT, even if you do get a kick in the butt for being a bit slow.
Pilots at work do NOT have that luxury!