I heard a rumor a year or two ago, that the FAA was looking into the idea of allowing pilots (on 2 pilot aircraft) to take short naps during the cruise phase, as long as the other pilot was awake and alert (and in his/her seat). I heard the thinking was this might have some benefits for the pilots on long sector flights, by allowing them to be more refreshed and alert during the high work load let-down and approach phases of the flight.
Anyone else heard of this? Would this actually be helpful in any way? Would it present any risks if allowed?