“Fatigue” is defined as “a non-pathologic state resulting in a decreased ability to maintain function or workload due to mental or physical stress.” The term used to describe a range of experiences from sleepy, or tired, to exhausted. The only effective treatment for fatigue is adequate sleep. Fatigue is a threat to aviation safety because of the impairments in alertness and performance it creates.
SLEEP AND SLEEP LOSS
Like food and water, sleep is necessary for survival. Sleepiness results when you don't get enough sleep. Like hunger and thirst, sleepiness is the brain's signal that sleep is needed. “Sleep loss” describes the phenomenon of getting less sleep than is needed for maximal waking performance and alertness. If an individual normally needs 8 hours of sleep to feel completely alert, and gets only 6 hours of sleep, 2 hours of sleep loss has been incurred. Sleep loss over successive days accumulates into a “sleep debt.” If the individual needing 8 hours of sleep gets only 6 hours a night for 4 nights in a row, an 8 hours sleep debt has been accumulated. The negative effects of one night of sleep loss are compounded by subsequent sleep loss. Sleep loss and the resultant sleepiness can degrade most aspects of human performance. In the laboratory, it has been demonstrated that losing as little as 2 hours of sleep can negatively affect alertness and performance. This includes: degraded judgment, situation awareness, decision-making, and memory; slowed reaction time; lack of concentration; fixation; and worsened mood. Other effects are decreased work efficiency, degraded crew coordination, reduced motivation, decreased vigilance, and increased variability of work performance.
One study showed that after being awake for 17 hours, you have the same actions (and reactions) as someone who has a blood alchol level of .05. Recall that you are not allowed to fly with a blood alchol level of .04. After being awake for 20 hours you are at a .08.
SYMPTOMS AND EFFECTS OF FATIGUE
Sleep-deprived pilots may not notice sleepiness or other fatigue symptoms during preflight and departure flight operations. However once underway and established on altitude and heading, sleepiness and other fatigue symptoms tend to manifest themselves.
When flight crewmembers find themselves flying when fatigued several warning signals should alert them of a dangerous situation. These include:
· Complex decision-making suffers, personality changes, and mood deteriorates. Your error rate increases by 50.
· Communication is impaired– people quit talking.
· Vigilance decreases and people become inattentive.
· Task-fixation develops as brain processes slow.
· Tolerance for both error and risk increase.
· Motivation is reduced, and effort is conserved – the brain tries to preserve its remaining resources.
· Short-term memory declines.
· Reaction times increase – this is one of the most fundamental measurable changes with fatigue.
· Risk of microsleeps goes up (nodding off).
Basicly, you feel like crap, fly like crap and don’t give a crap.
RESTFUL SLEEP REQUIREMENTS
There is considerable variability in individual sleep needs. Some individuals do well with 6 hours sleep per night, yet others need 9 or 10 hours sleep. However, most adults require 8 hours of restful sleep to stay out of sleep debt. With aging there is usually a significant decline in habitual daily sleep due to increased nighttime awakenings. Therefore, in older individuals decreased quality of nighttime sleep can result in increased daytime fatigue, sleepiness, dozing and napping. Napping seems to compensate for the loss of quality sleep during nighttime hours, but the need for a mid-day nap may not be compatible with flight demands.
Complete recovery from significant sleep debt may not occur after a single sleep period. Usually 2 nights of recovery are required. Eight to 10 hours of recovery sleep per sleep period may be required for most people to achieve effective levels of alertness and performance.
A WORD ABOUT SLEEP INDUCING MEDICATIONS
None of the non-prescription sleep preparations, including Sominex®, Tylenol PM®, and Excedrin PM®, are allowed by the FAA for flight deck use, and require waiting 12-24 hours from last dose to flight duty. Prescription medications such as Sonata®, Halcion® and Restoril® are not approved for airmen. Those pilots taking Ambian®, another prescription medication, must wait 24-48 hours after the last dose before flying. (Some of these medications have a “hang over” type of effect.)
Dietary supplements, such as melatonin, reportedly help reduce sleep problems. The FAA generally allows airmen to use these supplements if they do not suffer side effects from them. However, claims about dietary supplements' benefits in treating insomnia and jet lag often are overstated. Some individuals have significant side effects from these "natural" supplements.
Research has shown that several countermeasures for fatigue are effective in improving alertness and performance.
· Two good nights sleep prior to the flight (at least 8 hours)
· Avoid depressive medications and alchol
· Minimize pre-flight physical exertion
· Reduce heat / sun exposure
· Don’t Smoke
· Eating frequent small amounts – Proteins and complex carbohydrates
· Hydration (sports drinks)
· Oxygen increases alertness
· Strategic Napping – 25 - 40 minute nap
· Stretching – DVT prevention