As the year’s longest days arrive in the Northern Hemisphere, on either side of the summer solstice, we enter the worst time for standing the back watch. Why? Sleep, or the lack of it, on an unnatural timetable that defies all we know about human physiology, the need for rest, and the negative effects of not getting enough of it.
In short, for getting the sleep we need, sun exposure at the wrong time is bad, especially for the back watch. The back watch has historically been from 0000-0600 and 1200-1800 daily — the “wrong time” being prior to going to bed. Traditional six-on six-off watches are brutal schedules for humans, even in a low-stress work environment that isn’t safety-sensitive and doesn’t demand a high level of attention and skill. Operating a tug or towboat? It’s none of the above.
This schedule becomes significantly worse when you consider that during this time of year, the last hour or more of the night watch is actually spent being exposed to increasingly brighter morning twilight, dawn, and then the rising sun. The unavoidable effect of this is to trigger the release of hormones that make it harder to sleep, precisely at the beginning of the back watch’s normal primary sleep period of 0600-1200. It’s pure genius if the goal is to maximize fatigue. And this comes right after spending most of the watch in a performance degrading circadian low window. It’s no surprise that this period is notorious for an increase in inexplicable accidents.
There is a simple way to allow the back watch to get more sleep. Simply adjust the watch schedule seasonally to align with the length of the day by rolling watch relief times back, as needed, to get the back watchstanders below decks and in the bunk before the sun turns their own body chemistry against them. About 30 to 45 minutes before sunrise will do it. It’s really that simple. And what about captains on the front watch who just don’t care? Remember that your own personal safety off watch depends directly on the rest quality of the back watch.