All of our operations were conducted using a 24-hour clock set to Greenwich Time, which we referred to as Zulu time, Zulu being the name that NATO assigned to the time zone on the prime meridian. The clock for our daily lives, however, remained set to the local time zone. On one of our Atlantic crossings, we were assigned to a task force that traveled for a day, then stopped and conducted an exercise for a day, alternately all the way across the ocean. It was rare for a submarine to be assigned to a convoy any more, so we were surprised to find that, every two or three days, we got a message from the admiral telling us to set our clocks ahead to the next time zone at a specific time and day. We were upset at the loss of autonomy. Also, every two or three days, we had to deal with the time change.

Weeks later, on the return trip, we were all alone, and free to set our clocks to whatever we wanted. The memories of making six individual, disruptive time changes still rankled. When we got to the sea buoy as we left Lisbon, while 90% of us were still hung over, we simply set our clocks back six hours, and got it all over with at once.

Sure, it was a little confusing. The sun was rising at midnight and setting at noon. But only those of us who stood bridge watches knew that. Below decks, we turned off the bright white lights when the clocks said 6:00 p.m., and we turned on the dim red lights. The cooks, yeoman, corpsman, torpedomen, fire control technicians, sonarmen, electronics technicians, stewards, machinist's mates, interior communications electricians, enginemen, electrician's mates, and radiomen had no way of knowing when the sun was actually shining.

It worked well. Our circadian rhythms were stable and synchronized when we got to Charleston. What does the admiral know about these kinds of things, anyway?