Atlantic Maritime Academy

Asleep at the Switch?  Not on My Watch!

Many of us are involved in long passages over the water.  A ride out to The Canyons, for example, can take all day and night to and fro – and a long battle against a large pelagic fish would (hopefully) be in between.  How do we manage our sleep time?  This column is about that.

Quantity or Quality

Many sleep specialists will tell you that quality is more important than quantity.  By “quality”, what they mean is that you sleep enough to complete a number of distinct 90-minute sleep-cycles that our minds and bodies require.  Sleep specialists break-down that 90-minute sleep-cycle into these phases:

• 65 minutes of normal, or non-REM (rapid eye movement), sleep
• 20 minutes of REM sleep (in which we dream)
• Final 5 minutes of non-REM sleep.

If you can’t complete such a cycle, you aren’t having “quality” sleep and no matter how much quantity that you get, you won’t be rested.  Interestingly, sleep scientists now categorize sleep styles into 3 types:

• Monophasic – Like mom said, you lie down, sleep for 8 hours (one big block in other words), wake up and start your day.
• Biphasic – Common in many Latin countries, biphasic sleep is sleep in which there are two blocks of sleep in 24 hours, i.e. the night sleep and the typical Latin siesta.
• Polyphasic – Common in the animal kingdom (think about your house cat), this is sleep where you get many “naps” during the day such that you never feel the overwhelming urge to sleep all night long.

Many famous people are believed by some to have been “polyphasic” sleepers – Thomas Jefferson, Ben Franklin, Thomas Edison and Winston Churchill to name a few.  Whether they were or they weren’t, as a non-scientist but a life-long mariner, I recognize “polyphasic” sleep as instrumental in watch-keeping on long voyages with many tasks and a number of crew shifts to manage.  At the other extreme, that is, the alone-around-the-world races, I’m pretty sure that no one sleeps for 8 hours when they are the only person on the boat!

“Watches” Aboard Ships At Sea

On naval and merchant vessels, a “watch” is typically 4 hours.  Traditionally, many private boat captains mirror this as they set their crew watches for long duration passages.  This system has a couple of advantages: it's easy to remember and it's consistent. For example, a member of watch team #1 will only have to remember that he is on the "4-8" watch, and knows that he goes on watch at 4am and 4pm. This scheme also allows inexperienced watchstanders to only stand watch from 8-12am and 8-12pm, when senior watchstanders are likely to be awake and ready to assist in case of trouble.

Since you are “on” for 4 hours in a 12-hour cycle, it would seem that you can easily get your 8 hours of sleep that mom wants, no?  No.  For anybody that has been to sea knows, there are always things that need doing that interrupt your plan for “sacking out”, putting aside such things as the excitement of the passage, the roughness of the seas or some mechanical breakdown that needs addressing.  This gets directly back to the top of the column.  If you are getting quality sleep, the quantity won’t matter.

1. Right before you crash, down a cup of java. The caffeine has to travel through your gastro-intestinal tract, giving you time to nap before it kicks in.

2. Close your eyes and relax. Even if you only doze, you’ll get what’s known as effective microsleep, or momentary lapses of wakefulness.

3. Limit your nap to 15 minutes. A half hour can lead to sleep inertia, or the spinning down of the brain’s prefrontal cortex, which handles functions like judgment. This gray matter can take 30 minutes to reboot.