I'm glad to hear this. Several jobs ago I worked with some of these submariners and -- between work and banter -- would hear of the [current//olde] sleep schedule and its influences on them and their lives. I'd get in to work, down the hatch at some late evening hour [I was on civilian shift work time], and the person on duty would be having a call to his significant other about Life Issues [rent, kids, whatever]; conversations usually had by civilians at more normal hours and places. Nevermind that he'd be 3 hours into his second 4-hour shift out of the past 12 hours, and he'd be that tired.