 My mind clicks on and off. I try litting one eyelid close at a time while I prop the other with my will. But the effect is too much. Sleep is winning. My whole body argues dully that nothing, nothing life can attain is quite so desirable as sleep. My mind is losing resolution and control. Flying solo for 33 hours and 30 minutes straight. His objective was to be the first to fly nonstop from New York to France. While Charles Lindbergh made history by traveling over 3,600 miles across the Atlantic, he also provided the aviation community with insight as to what it's like to fly when one is deprived of sleep or simply too tired. Got to. I mean I can't call the guys this late. You didn't fly when you're like this. Your eyes look terrible. Do you have a fever? I've been in a lot worse shape than this and flown and everything turned out okay. I think there's something else that's bothering you. What's wrong? From such early beginnings, scientists have learned that fatigue is dangerous, especially when one is unaware of the conditions that cause it. Clinically, fatigue is defined as a state of diminished physical or mental efficiency. Numerous occupations necessitate that their employees conduct shift work. Changes are just now beginning to redefine what is considered appropriate work limits aimed at reducing fatigue on the job. In aviation, commercial pilots are familiar with working alternate time periods while factoring in the crossing of multiple time zones and changes in work schedule. However, it must be realized that any pilot that is fatigued before flight applies to subject to the same dangers as the commercial pilot flying long legs over multiple time zones. It's important to recognize that employees who work shifts may be affected by both short-term and long-term fatigue. Shift workers subject themselves to increased risk of lowered alertness and reduced performance capacity, especially during the first few days following a shift change. Because of the natural tendency for humans to want to extend the day, it appears that it is better to shift forward in a time change or move clockwise when changing to a new shift. Short-term fatigue, also known as acute fatigue, is typically experienced at the end of a long, hard day. While long-term fatigue, also referred to as chronic fatigue, develops over a period of time, it can sneak up on you and it has serious physiological and psychological effects. Fatigue is something that affects everyone, particularly those in the aviation community. A NASA study of regional airline pilots found that 89% rated fatigue as a moderate to serious concern. 88% say that fatigue is a common occurrence. And 86% of regional airline pilots report that they have not received any training from their companies on the topic of fatigue. Here are some observable effects of fatigue. Loss of appetite, weight loss, insomnia, depression, irritability, slurred speech, apathy, physical and emotional isolation from others, decreased alertness and attention. Those factors that affect one's tolerance to fatigue might be divided into three categories, individual, environmental and operational. Individual fatigue tolerance factors are those features that are very specific to each person. Individual fatigue takes into account poor physical fitness, poor sleeping habits, improper diet and inadequate nutrition, dehydration, excessive body weight, drug or alcohol use, use of medications, non-prescription and prescription, excessive caffeine consumption and use of tobacco. Environmental fatigue tolerance factors involve those aspects that can affect an individual in their immediate surroundings. Environmental fatigue is caused by family, work environment, bad weather during flight, noise, vibration, G-forces, high and low ambient temperatures and low humidity. The last fatigue tolerance factor is operational. Operational factors include the type of work performed and when it is performed. Examples of operational fatigue include heavy work schedule, multi-time zone operations, shift work, night operations. Obviously, there are many factors that can affect one's susceptibility for fatigue. The major causes of fatigue are emphasized by sleep loss, work schedules, circadian rhythm disruptions, recreational or extracurricular activity. During sleep, the physiological and psychological functions of the body get refreshed. Some very interesting but basic concepts have been derived from sleep research studies which are useful when learning to limit personal fatigue. Sleep is as necessary as food and water. Humans require about 7 to 8 hours of sleep each day. Your personal sleep requirements may vary and the amount and quality of sleep you get is likely to change throughout your lifetime. Because of these changes, people tend to underestimate their sleep requirements. Sleeping fewer hours per day than in what is required results in sleep loss or sleep deficit. This loss is cumulative and results in sleep debt. However, to successfully recover, a person does not have to sleep the same number of hours that were originally lost. The most notable recovery feature from sleep debt is an increased depth of sleep rather than an increased duration. As one might imagine, there are several causes that contribute to sleep loss. They include, circadian rhythm disruptions, sleep disorders, use or abuse of alcohol and drugs, excessive consumption of caffeine, bad sleeping habits, an uncomfortable sleeping environment, use of sleep aids. Over time and with age, nighttime sleep becomes shorter, lighter and more disturbed with more awakenings. Regardless of the cause for sleep loss, the physiological effect is fatigue. Some normal daily activities may disrupt normal circadian rhythms, which may lead to sleep loss and fatigue. Circadian rhythm is defined as a biological cycle of approximately 25 hours. This rhythm determines the physiological behavior or activity levels of all body functions. The succession of day and night, changes in ambient illumination, the timing of meals, as well as physical and social activities all affect the circadian rhythms of the body. As a pilot, the greatest threat to your circadian rhythm is flying through multiple time zones. A rule of thumb for time adaptation is this. For every one hour of change, one day is required for adaptation, with complete adaptation taking at least three full days. It is easier to adapt to time changes for westbound flights because it involves extending the workday, rather than eastbound flights, where the day is shortened. Since everyone is physiologically different, factors affecting adaptation rates will vary with each individual. Vacations, social events and recreational activities tend to disrupt normal sleep habits and circadian rhythms. As a result, we tend to overestimate our energy levels during these functions. The fatigue problem begins when we are required to return to our routine schedule after participating in such activities. So how does fatigue affect performance in the flying environment? Persons suffering from fatigue are more apt to demonstrate these symptoms. Channelized attention. Poor judgment. Slowed reaction time. Inattention. Ease of distraction. Technical errors resulting in task saturation. Fatigue is a safety of flight issue. It's important that you learn how to recognize it, deal with it and know the preventive methods needed to reduce fatigue. Starting with good physical fitness. Adequate food and sleep. Adequate rest and relaxation periods. Under normal flying conditions, you may be able to handle any situation or solve any problem that develops. The concern is how you react to an in-flight emergency or a highly intense period of stress when fatigue is present. Hey, do you have the report ready yet? Whoa, man, back off. It's not even due till tomorrow. Whoa, calm down. I'm just checking the status of the report. Is everything okay? Man, I'm sorry, I'm sorry. I'm just tired. I haven't had enough sleep in the last couple of nights. So why haven't you made getting enough sleep? The Federal Aviation Administration requires pilots to have at least 8 hours of rest in a 24-hour period. This may or may not be enough to recover fully. You're your own advocate. Research shows that pilots are poor judges of their own fatigue level. A family member. Well, you're not going to fly today, are you? A good friend. Man, you look beat. Should you be flying today? Or another crew member may be able to assess your level of fatigue better than you can. Get someone else's input before putting yourself behind the controls. As a review, fatigue is defined as a state of diminished physical or mental efficiency. Pilots and crew members may be affected by both short-term and long-term fatigue. Some observable effects of fatigue are loss of appetite, weight loss, insomnia, depression, irritability, slurred speech, apathy, physical and emotional isolation, decreased alertness and attention. The factors that affect tolerance to fatigue are individual, those that are specific to each person, environmental, those that can affect the individual in their immediate surroundings, and operational, factors from the type of work performed and when it's performed. The major causes of fatigue are sleep loss, work schedules, circadian rhythm disruptions, recreational or extracurricular activity. The unfavorable effects of fatigue on flying skills are channelized attention, poor judgment, slowed reaction time, inattention, ease of distraction, task saturation. Pilots are poor judges of their own fatigue level. A family member, a good friend or another crew member may be able to assess your level of fatigue better than you can. I'll tell you what I'll do. I'll take your flight today, you go home and get some rest. Get someone else's input before putting yourself behind the controls. Fatigue is something that can be prevented by taking appropriate pre-emptive measures. Plan to get enough sleep. Do what you need to do to ensure quality sleep, even if that means wearing earplugs and an eye mask. Eat well and exercise. Reducing your chance for fatigue potentially reduces costly errors.