Disclaimer! This
is NOT an opinion piece, but rather a collection of various readings
and clippings which
serve to spur further exploration in the topic. These are not full
articles but simply excerpts from the bulk of reading material that is
available. As much
citation and references were taken with regards to the topic. Legitimacy
and
accuracy of the clippings are read at your own discretion.
Fatigue and You
From the standpoint of performance, as fatigue increases, accuracy and timing degrade, lower standards of performance are accepted, the ability to integrate information from individual flight instruments into a meaningful overall pattern declines, and attention narrows (Caldwell & Caldwell, 2003).
Severely fatigued pilots may even experience perceptual illusions because of brief, involuntary lapses into sleep. As sleepiness increases, performance becomes less consistent, especially at night, when there is often a five fold increase in lapses in vigilance (Dinges, 1990). Since 1990 the US National Transportation Safety Board has placed pilot fatigue on the Most Wanted List of safety related priorities.
Severely fatigued pilots may even experience perceptual illusions because of brief, involuntary lapses into sleep. As sleepiness increases, performance becomes less consistent, especially at night, when there is often a five fold increase in lapses in vigilance (Dinges, 1990). Since 1990 the US National Transportation Safety Board has placed pilot fatigue on the Most Wanted List of safety related priorities.
Within 24 hours of continuous wakefulness, levels of self-rated depression, confusion, and fatigue increased, and there were substantial elevations in slow-wave EEG activity (of the type usually associated with Sleep Deprivation and Aviation Performance 87 extreme drowsiness).
On a secondary task in between simulator flights, there was a 20 percent lengthening of reaction time, a 100 percent increase in incorrect responses to warning signals, and a 60 percent reduction in basic psycho motor tracking ability.
On a secondary task in between simulator flights, there was a 20 percent lengthening of reaction time, a 100 percent increase in incorrect responses to warning signals, and a 60 percent reduction in basic psycho motor tracking ability.
A report from an NTSB study of major accidents in domestic air carriers stated that “crews comprising captains and first officers whose time since awakening was above the median
for their crew position made more errors overall, and significantly more procedural and tactical decision errors” (National Transportation Safety Board, 1994, p. 75). A Navy Safety Center study cited fatigue as the second-most problematic factor, after spatial disorientation, in aeromedically related mishaps and hazard reports (Command Flight Surgeon, 2005).
Conservative estimates are that fatigue is responsible for 4 to 7% of civil aviation mishaps (Lyman & Orlady, 1981), 4% of Army aviation accidents, 12% of the Navy’s most serious aviation mishaps, and almost 8% of the Air Force’s Class A (most severe) aviation mishaps (Caldwell et al., 2009).
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Clearly fatigue is fundamentally the result of insufficient sleep,
but for pilots the important issue is the consequences of that sleep
loss when they are sitting at the control panel. The author suggests that “fatigue related risks increase substantially when
(a) the waking period is longer than 16 hours,
(b) the pre-duty sleep period is shorter than 6 hours, or
(c) the work period occurs during the pilot’s usual sleep hours.
The two most important variables for alertness are recent sleep and the body’s natural circadian rhythm” What that means is that when a pilot reports for duty, he or she should have had from seven to nine hours of good sleep within a reasonable period of time before work and that as often as possible, the work schedule is in some harmony with the pilot’s natural daily rhythm.
Fortunately, new Federal Aviation Administration regulations better account for the true physiological nature of fatigue, but additional fatigue-management strategies are needed.
Caldwell acknowledges that the very nature of airline travel predisposes pilots to disrupted sleep schedules, but he points out several approaches that can both predict a truly impaired pilot and mitigate the consequences of a lack of sleep.
Controlled Rest and getting the most out of it
The NASA study compared alertness among trans-Pacific airline pilots. It “allowed one group of pilots flying across the Pacific to take a 25-minute nap while their co-pilots flew the planes, while a control group was required to stay awake for the entire flight.
Those without the naps nodded off five times as much – including while on the approach to the airport – as those who got some sleep,” reported the AP in 2009.
Some foreign carriers have adopted the conclusions and now allow pilots to take short naps on long flights while co-pilots remain awake. But the FAA and US carriers have resisted the changes.
Pilots in the rest group typically fell asleep quickly, slept “efficiently” for an average of 26 minutes and, after awakening, displayed “improved physiological alertness and performance,” compared with colleagues in the no-rest group, according to the researchers’ report.
“The benefits of the nap were observed through the critical descent and landing phases of flight,” the report said. “The nap did not affect layover sleep or the cumulative sleep debt displayed by the majority of crew members. The nap procedures were implemented with minimal disruption to usual flight operations, and there were no reported or identified concerns regarding safety.
30mins or less Power Naps & Sleep Inertia
The NASA sleep researchers and
others believe that properly planned napping strategies can be effective
against fatigue, preventing many of the attention lapses and
micro sleeps periods of sleep that last only several seconds and
often are not recognized encountered during long-range flight
operations. 
In addition to its benefits, napping also has a negative aspect. “Practically everyone,” Caldwell said, “experiences post-nap grogginess.” This grogginess also is referred to as “sleep inertia,” which manifests itself in degraded vigilance, increased drowsiness and diminished performance for one to 35 minutes after awakening.
Sleep inertia is an important consideration in the scheduling of cockpit naps, sleep researchers have said.
ALPA’s Prater agreed, adding, “Trying to come up out of a nap to make a snap decision is difficult.” Those who favor in-seat napping agree that planning must take into consideration several factors.
As MA’s recommendations call for no more than 40 minutes to be set aside for an on-duty, in-seat nap. The time limit was derived from the NASA studies and other sleep research that has shown that a sleep period of less than 30 minutes is less likely to be followed by excessive sleep inertia.
Coffee Power Naps. Paradoxical?
What explains the power of the coffee nap? It all boils down to body chemistry specifically, to the competing effects of caffeine and adenosine, a drowsiness-inducing chemical compound that accumulates in your brain when you’re awake and dissipates as you sleep.
If you want to try it yourself, have a coffee beforehand – espresso is a good, quick fix – so that it takes effect towards the end of your nap, or controlled recovery period (CRP). Don’t sip your coffee too slowly, as you might find it’s already taking effect as you begin your CRP, and be aware of the amount of caffeine you have already consumed.
Caffeine’s alertness-boosting effect typically peaks about 30 minutes after the stimulant is consumed. So by sleeping for 20 or so minutes of those 30, you can reduce the amount of adenosine the caffeine has to compete with. And voila, the caffeine has a greater effect.
“If you can fall asleep in your nap before caffeine does that, when it’s time to wake up, you’re getting the benefits of the caffeine perfectly timed with the nap sleep benefit,” sleep researcher Dr. David Dinges, a professor in the department of psychiatry at the University of Pennsylvania, told The Huffington Post.
Dinges recalled a 2001 study in which 28 men and women were given either a low-dose caffeine pill or a placebo during the latter stages of an 88-hour period during which the sleep they got came only in the form of seven two-hour naps. In that experiment, the caffeine was successful in overcoming so-called sleep inertia. That’s a term scientists use to describe the grogginess you feel immediately after waking up.
That’s not the only evidence of the curious relationship between caffeine and napping. In a series of studies conducted in the 1990s, researchers at Lough borough University in England found that drinking a cup of coffee and then immediately taking a 15-minute nap was better at curbing drowsiness in motorists than simply having a cup of coffee or taking a short nap (the motorists’ alertness was measured not on the road but in a driving simulator).
Sources:
Crew Schedules, Sleep Deprivation, and Aviation Performance (PDF Download Available). Available from: https://www.researchgate.net/publication/254081761_Crew_Schedules_Sleep_Deprivation_and_Aviation_Performance [accessed Oct 17 2017].
https://www.researchgate.net/publication/254081761_Crew_Schedules_Sleep_Deprivation_and_Aviation_Performance
https://www.psychologicalscience.org/news/releases/crew-schedules-sleep-deprivation-and-aviation-performance.htmlJ. A. Caldwell. Crew Schedules, Sleep Deprivation, and Aviation Performance. Current Directions in Psychological Science, 2012; 21 (2): 85 DOI: 10.1177/0963721411435842
http://www.dtic.mil/dtic/tr/fulltext/u2/a519631.pdf
https://www.huffingtonpost.com/2014/09/03/coffee-sleep-power-naps-science_n_5753360.html
https://www.theguardian.com/lifeandstyle/2016/oct/23/the-secret-of-power-napping
https://flightsafety.org/wp-content/uploads/2016/11/asw_dec09-jan10_p38-42.pdf
Image Sources
https://i.ytimg.com/vi/aQSDZOZ0cJ0/hqdefault.jpg
https://blog.bulletproof.com/coffee-naps-bulletproof-power-nap/
http://www.jetpix.com/airspacestealth/
https://www.flightdeckfriend.com/
http://www.collective-evolution.com/2016/05/30/naps-why-theyre-important-how-long-they-should-be-for-the-biggest-brain-boosting-benefits/
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