Perhaps, if safety systems and procedures are sufficient enough, pilots, including pilots of passenger planes should be allowed the option of sleeping during non-demanding, non-serious/non-significant portions of the flight. However, at least one member of the cockpit crew should be awake and in the cockpit, at the controls, at all times. All members should be awakened at least 15 minute before major planned events, like takeoffs, landing, etc., or reasonably foreseen/predictable events, like turbulence, flying in or near storms, heavy air traffic, etc. Pilots allowed/required to sleep during very long flights could be allowed to fly beyond their daily hourly limits.