I did a sea tour in engineering on an aircraft carrier, and we would get in the routine of standing watch, eat, go work on paperwork in the office, sleep, work out, eat, stand watch, repeat for days and days on end. Not in a bad way, I didn't mind it, I was young, it just got to be routine to spend your entire existence within a sphere of around 150 meters or so. After a while, me and my friends realized that it was unhealthy, so we started going outside to get some sun and watch the airplanes landing and taking off.
And then, on a later topside tour, I was standing 3-section watches and then one of the other guys transferred so we went to 2-section watches (port and starboard) while I trained the new guy. The problem was that the new guy was also my roommate on the ship. So we'd stand watch for 6 hours together, go eat together, go back to the stateroom and sleep at the same time (in bunk beds, of course), wake up, eat, go back on watch together. Except for bathroom breaks, we literally spent 24 hours a day together. It only took 3 or so days of that before we were both begging for the sweet release of death...