Sleep and Fatigue — Page 216, Lesson 343

I want to walk you through the section on Sleep and Fatigue, starting with naps and microsleeps, then moving into shift work. Let’s begin. First, a quick note on age and gender differences. As people get older, they sleep less, but they also become less flexible about when they can sleep. That means shift work becomes more difficult with age because it’s much harder to reprogramme the body clock. Women tend to sleep longer than men, but they also report more sleep problems. Now, let’s talk about naps. A nap is a short period of sleep taken at any hour. The time of day you take it, the duration of the nap, and your current sleep credit or deficit — that is, how much sleep you have or haven’t had recently — will determine which sleep stages you pass through. The restorative properties of naps vary from one individual to another. People who habitually take naps appear to gain more benefit than non-habitual nappers. In fact, non-habitual nappers sometimes perform at a reduced level for some time after waking from a nap. With the increase in extended flight times, there is debate about allowing a crew member to take 20 to 30 minute naps in the seat to keep them fresh. There appears to be some benefit, but pilots should be aware of the pitfalls. It is not unknown for one pilot to be taking a nap and the other pilot to fall asleep as well — so you have to be careful about that. Pilots should also be aware that after napping, it may take some minutes to collect your thoughts, and you will have slow responses and reactions for up to 5 minutes after being roused. The minimum duration for a nap to be restorative appears to be not less than 10 minutes, according to Hawkins. It is strongly recommended that pilots plan to be fully awake at least 1 hour before descent. Now, microsleeps. Microsleeps are very short periods of sleep lasting from a fraction of a second to two to three seconds. Their existence can be confirmed by EEG readings — that’s an electroencephalogram, which measures brain electrical activity. But here’s the dangerous part: the individual may be completely unaware that a microsleep has occurred. That makes them particularly dangerous. They occur most often in conditions of fatigue, but they are of no assistance in reducing sleepiness — they don’t help you catch up on sleep. Let’s move to shift work. Sleep loss or partial sleep is an occupational hazard of commercial aviation. There will be times when the pilot has to work when they would rather be asleep, and other times when they have to sleep when they would rather be awake. At these times, sleep problems may be aggravated by circadian rhythms — your internal body clock. The sleep/wake cycle affects readiness for sleep, and the timing of sleep relative to the body cycle of temperature is critical in determining how long you will actually sleep. Let’s look at planning shift work sleep. As an example, assume you are rostered for night duty. You will try to get some sleep during the afternoon before reporting for duty. However, it will be difficult to get any satisfactory sleep because you have a good sleep credit — assuming you had a normal night’s sleep the night before — plus an increasing body temperature does not facilitate sleep. Your body temperature naturally rises through the afternoon, making it harder to fall asleep. There are basically two options in this case. First, you could go to bed early the previous night and set the alarm for an early call. That way, by the afternoon, your body will be approaching sleep deficit and be ready for sleep. The second option is what we’ll pick up next.