Chronic fatigue syndrome: causes, symptoms, and treatment approaches

Chronic Fatigue in the Aviation Industry

Chronic Fatigue

Fatigue is the mental and/or physical state of being weak and tired. Mental and physical fatigue is different, but the two will often exist together. A person becomes mentally tired if they are physically exhausted for a long period. A person being unable to function physically at their normal levels manifests physical fatigue Jackson & Earl, 2006.

Mental fatigue will manifest itself by a sleepy feeling and inability to concentrate properly. In medical terminologies, fatigue is not a sign, but rather a symptom. This means that a person suffering from fatigue is able to feel and describe the condition. Experts have indicated that around 10% of people globally suffer from persistent tiredness at any one time. Females are more prone to persistent tiredness than males. It is not easy to define fatigue in humans because of its large variability of causes. The causes of fatigue range from circadian rhythm disruption to boredom to heavy physical exertion John A Caldwell, 2005.

In nonprofessional terms, fatigue is defined as weariness. For a more accurate definition fatigue is a condition that is characterized by increased discomfort that leads to loss of power, a lessened capacity to work, the capacity to respond to stimulation, or reduced efficiency of accomplishment, and this is normally accompanied by a person feeling tired and weary.

The consequences of fatigue are insignificant for an average person, but for persons working in safety-related environments like piloting an aircraft, operating a motor vehicle, running a nuclear reactor, or performing surgery the consequences can be disastrous. In the aviation industry, fatigue is an important factor, which is associated with shift work and loss of sleep. Long duty cycles can cause flight crews to become careless, inefficient, and inattentive Jackson & Earl, 2006.

According to John A Caldwell et al. (2009)

aircrews suffer from fatigue due to irregular work-rest cycles, transmeridian flights, and other work related factors. The frequent loss or disturbance of sleep experienced by the flight crews also leads to fatigue. Fatigue has led to errors, incidents, and other problems in the aviation industry. According to NASA, fatigue attributed towards 21% of the reported aviation incidents. Crews flying all aircraft sizes face fatigue problems, and this is a continuing problem.

Causes of the problem

There has been a significant evolution in the operational demands and aviation technology, but the need for sleep by the human operators has remained. No amount of technology can counter the need for sleep especially if the technology requires a human operator. Fatigue can degrade many aspects of performance, including decision-making, judgment, reaction time, memory, selective attention, fixation, concentration and mood. Avers and Johnson (2011)

posits that the low arousal that sleep loss produces is accompanied by greater decrement in performance on simple tasks. With the simplification of the aviation process by technology, it has contributed towards this performance decrement. The amount of sleep required by individuals differs, but studies have suggested that most people require around eight to nine hours of sleep per night. Non-shift workers generally sleep more than shift-workers. Pilots claim they need at least 7.5 hours of sleep a night. Sleep timing influences the duration of sleep. Hence, the crossing of time zones can lead to cumulative sleep deprivation. People have the capability to deal with small amounts of fatigue, and catching up on a night's sleep will assist in working it out of their system. However, the continuous accumulation of fatigue could lead to potentially dangerous effects. Circadian rhythms and sleep debt are the two main causes of fatigue.

Circadian rhythms

A person's body temperature, human error, alertness, and sleep tendency follow a 24-hour pattern. The body has a steady 24-hour biochemical, behavioral, and psychological rhythm. These rhythms are the circadian rhythms. Human beings are diurnal creatures, meaning they are awake in the daytime, and they sleep at night. Exposure to light affects the human body clock especially the early morning light. A person's circadian rhythms are very reliable such that even if the person is removed from their 24-hour rhythm of day and night, the rhythms continue to run. Circadian rhythms affect aviation workers especially those working the night shift. Even with enough sleep during the day, the workers still experience fatigue while working. This is not caused by their lack of enough sleep, but rather by their natural circadian rhythms.

Understanding the circadian rhythms is vital especially in the aviation industry. The managers would be aware of what their employees experience and will develop strategies that would mitigate the risks associated with circadian rhythms. In the regulation of sleep, circadian rhythms play a vital role. There are chemical changes naturally occurring in the body when it is preparing to sleep. This typically occurs between 8pm and midnight. At around 3am, a person's body temperature will reach a low point, and then it begins to rise steadily as the body prepares for the day ahead. This will occur way before most people are awake. Managers need to recognize that the most critical time for their shift workers is between 2am and 5am. This is the window of circadian low. A person's body temperature is lowest at this time and their mental alertness poorest. The likelihood of employees making errors increases at this time. Aviation workers also experience this circadian low moment and the flight crews are most likely to cause incidents. During the circadian low moment, sleepiness reaches its peak. This time a person will feel tired, and they will start to experience bouts of sleep. If piloting an aircraft, the pilot is at a disadvantage if he starts to doze off. They might interfere with flying instruments unknowingly or might be unable to respond quickly to any mishap that occurs.

Another peak in sleepiness occurs between 3pm and 5pm. This is the afternoon nap window for most people. A person whose sleep is disturbed, or had a restricted sleep at night, will find it hard to stay awake in the afternoon nap window the next day. Taneja, 2007()

argues that employees affected by the circadian rhythm and have a can-do attitude, will struggle to stay awake and continue to perform their tasks as normal. This is dangerous, as the employee would have a slow reaction speed, prone to errors, and decision-making is poor. The employees need to understand their circadian lowest time and avoid performing safety critical work. This will reduce the number of incidents on the ground, but in the air, things are different. Pilots and flight crews have to remain alert at all times as any loss of consciousness can have severe consequences.

Sleep debt

Adults need around seven to eight hours of sleep a night, but this need varies between people Caldwell Jr., 1997.

A century ago, people slept for around nine hours a night this was before the widespread usage of electric lighting. Today, work commitments, television viewing habits, and family demands combine to limit the amount of time a person sleeps a night. In the busy aviation industry, there are many people suffering from sleep deprivation, and they are not aware of it. Suffering from extreme sleep deprivation could have severe health effects, but mild sleep deprivation can even affect an employee's health and their ability to perform normal simple tasks at work and their personal lives Signal, Ratieta, & Gander, 2006.

Sleep debt builds up every time a person obtains less than normal sleep. With every successive night of inadequate sleep, a person adds up their sleep debt. Reducing sleep by only one hour a night on several nights could reduce a person's mental capacity.

Shift workers who work at night have to sleep during daylight hours, and this causes them to build up on sleep debt. Daytime sleep is brief and of poor quality, when compared to night sleeps. This indicates that the workers will increase their sleep debt if they work the night shift for long. Providing the shift workers with alternating schedules after a full day off will ensure they clear their sleep debt John A. Caldwell, 2012.

Aviation workers have no option since the industry operates 24-hours a day. Therefore, there will always be workers in the night shift. To reduce sleep debt, shift workers operating during the night should ensure that their bedroom do not allow any light during the day. Light affects a person's sleep patterns and reducing the amount of light will increase the person's sleep time. Research has shown that shift-workers experience one to two hours of sleep loss every 24-hours.

Family commitments and nature of work will deny a person enough sleep, which will increase their sleep debt. Other factors can lead to sleep debt like drugs, alcohol, and medical conditions. Insomnia, restless legs syndrome, sleep apnoea, and periodic limb movements are medical conditions that can interfere with a person's sleep patterns and time.

Scope and magnitude of chronic fatigue

A majority of people in the aviation industry see fatigue as normal and unavoidable. They argue and consider that if a person puts in enough effort, they can continue to perform their work effectively. Increased concentration and effort might assist the workers for a few minutes, but this does not compensate for fatigue during the entire shift. People need to understand that fatigue is real and can have a detrimental impact especially on safety in aviation. Employees need to balance between rest, work, and play for them to continue performing safety-critical tasks. Fatigue is not a sign of weakness, and it can reduce the flight crew's ability to fly safely John A Caldwell & Caldwell, 2005()

When fatigued a person's attention reduces, which makes the person leave out steps in the performance of their tasks. In aviation, leaving out a single step could have adverse effects on the aircraft. It is vital that the workers maintain their attention to detail and follow all the steps for successful completion of their tasks. The omitted step could be critical to the safety of the aircraft or passengers. Reduced attention makes a person to get preoccupied with single steps or tasks. Too much concentration on a single task reduces the time a person has to work on the other tasks. This can lead to failure to perform all tasks as time is wasted concentrating on a single task. The aviation industry is time critical, and any delays could lead to losses to the company. Workers have to perform their tasks within a given period and if fatigued a worker will no manage to complete their tasks. This means the worker will omit some tasks or they rush to complete them, which could lead to errors. Reduced attention leads to poor performance and the worker is unaware of this, which makes them to continue with their tasks as normal. Poor performance can have negative effects. If the worker is a cargo loader and they load cargo incorrectly, the aircraft is not well balanced, and the pilot is unable to control the aircraft. Fatigued pilots will experience tunnel vision, and they are unlikely to notice the unexpected. Tunnel vision will cause the pilots to operate an aircraft without noticing anything that is out of place. In case a mishap occurs, the pilot is unable to notice and correct it early. The amount of effort required for the worker to concentrate on a single task is enormous. They will use a lot of energy trying to concentrate on one task, and this makes them more tired and stressed out.

Diminishing of memory is another effect of fatigue. This will lead to poor memory for underway and completed tasks. Multi-tasking is vital for safety-critical environments. Recalling the progress made in the different tasks underway will ensure that a person is able to complete all tasks as scheduled. With diminished memory due to fatigue, the worker is unable to recall the tasks they have completed and the ones underway. Repetition of some tasks is likely and underway tasks forgotten. Wastage of time, as the worker does not perform all tasks on time and they require more time to complete all their tasks. Diminishing of memory could lead to a worker forgetting to perform all requisite tasks or omit some steps. If a situation arises and the worker has to interrupt some tasks, they are likely to forget about the interrupted tasks. It is only after asking them about the tasks that they will recall.

Another performance category that fatigue affects is mood, which makes a person be withdrawn. With a withdrawn mood, the person does not communicate effectively, and they reduce their communication. Communication is critical in the aviation industry. Pilots have to communicate with the tower people in order to receive guidance while in the air. Aviation workers should provide feedback and communicate in order to avert any incidents. If an employee does not respond to the others, they hinder the other workers progress, as they cannot advance with their responsibilities without feedback from the others. Reduced communication can affect the other crewmembers. Flight crews' should communicate in order to confirm and operate an aircraft effectively. Reduced communication means the other crewmembers will avoid communicating with the moody worker and this might affect the flight safety. A moody worker is very irritable, and they might snap at any time. Giving such a worker stressful responsibilities will increase their irritation and they might fail to accomplish their task. Some minor problems or difficulties could irritate the worker.

There is reduction in reaction time when a person is fatigued. The person slowly notices problems, and they have less control of equipment. When fatigued a person is unable to react fast to problems, which leads to incidents that could be avoided. The aviation industry is technologically advanced, but with all the advancement, human interaction is required in the operation of the equipment. Fatigued workers have less control over the equipment, and they are less likely to operate the equipment smoothly. This increases the chances of incidents occurring as they operate the equipment.

Hazard and exposure

The most obvious hazard of fatigue is the fatigued worker falls asleep while working. In 2008, Air-traffic controllers radioed flight 1002 for 18 minutes without any response from the pilots. The two pilots had fallen asleep while flying from Honolulu to Hilo. For 18 minutes, the pilots cruised past their destination before they woke up and returned for a safe landing. This was a fortunate scenario since no accident occurred, but if the pilots had touched or pressed any control while asleep, the consequences would be different. Microsleep is another form of falling asleep. This is a brief moment of between two and thirty seconds. Microsleep is the first stage of sleep, and the person's eyes still open. During the microsleep period, a person will lose consciousness, and they will not be aware they have experienced a microsleep. If they continue to perform their simple repetitive tasks, they are likely to fall into deep slumber or make errors of judgment. If the task been performed is of low risk this is not critical, but if they are operating an aircraft or operating sensitive equipment the results are different. For the flight crew, microsleep would have different results. The aircraft travels at 250 knots along the glide path, and it will cover over 400 feet in a second. Having a microsleep for just a second would mean that if anything occurs in the 400 feet been travelled the crew would not react on time.

In aviation, the safety implications of fatigue are reinforced using research findings from other transport industries. Researchers have studied truck drivers using sleep-monitoring equipment. The results indicated that some drivers showed signs of the first stage of sleep when driving along interstate highways. This is very dangerous, and if the same is applied to aviation, which requires longer flight duration during odd hours then it is clear that fatigue is the cause of the many incidents in aviation. According to research, sleep deprivation impairs the brain and produces the same effects similar to alcohol consumption Rosekind et al., 1994.

This could result in tragedy especially in the aviation industry.

Fatigue affects a person's hand eye coordination making it harder for the person to perform simple tasks with their hands. In the aviation industry, pilots rely on their hands and eyes to ensure they perform their duties correctly. If the pilot is fatigued, they will make silly mistakes as their hand eye coordination is affected. This might not have serious consequences, but the pilot touches the wrong instrument mistakenly they would not notice their error till it is too late. Flight crews rely on the control tower to provide them with instructions especially regarding altitude. This ensures that no two planes are at the same altitude approaching each other. A fatigued pilot would change their altitude and not realize the mistake. If the control tower does not correct them early, the plane would collide with another airplane if they were at the same altitude.

Pilots perform monotonous and repetitive tasks once the aircraft takes off. This can increase the risk of fatigue. Operating an aircraft requires concentration and doing this for long periods could lead to mental fatigue. Flight crews have a schedule on how they perform each task once they take off, and since they have performed this many times they might overlook some things since they are not concentrating fully on the tasks they perform. They have formed a routine, and if they omit a step in their routine, they might not realize the omission. This makes them careless not intentionally, but due to performing the repetitive tasks for a long time.

There are environmental conditions that flight crews experience. The conditions are vibrations, heat, and cold. Vibrations come from the turbulence experienced when flying. Turbulence affects the flight crew as they tire quickly, which can impair their performance. Exposure to extreme weather conditions has negative effects on the flight crews. Extreme conditions make the crew tire quicker and reduce their performance levels Bennett, 2003.

Aviation workers who have long commutes to and from work are more at risk of fatigue. The workers have less sleep time as they spend more time commuting instead of relaxing. Long commutes affect the workers, as they get tired travelling so when they report for duty they already feel tired. Tiredness could result in fatigue as the worker is not fresh and his/her body needs some rest. Continuous crossing of time zones results in jet lag, which leads to poor sleep. The workers require at least 24-hours in order for them to accustom to the new time zone and rest enough.

Control, prevention, or intervention

In the aviation industry, there are various duties that worker perform. In order to address risks associated with fatigue, workers should spend less time performing mentally and physically demanding work. This will ensure that the workers have ample time to relax and concentrate on their duties. Performing physically demanding work for long periods makes workers more tired and prone to making errors. They also lose concentration quickly since their bodies are tired. Mental work takes a toll on workers, and too much mental work leads to reduced concentration. In scheduling of work, managers should provide for ample breaks in order to increase the workers concentration levels. Any safety-critical work like fueling airplanes requires full concentration from the workers. Scheduling this duty outside the circadian low period reduces the chances or errors O'Connor & Flin, 2003.

During the circadian low period, workers should only perform tasks that are less critical. This ensures that if there is any fatigue related problem it does not result in major incidents.

Flight crews should not work beyond their scheduled work periods Leigh Signal, Ratieta, & Gander, 2008.

Providing flight crews with incentives that encourage them to work past their normal work hours could lead to disaster. The workers would push their bodies beyond limits and this will make them less attentive and more likely to make errors in their duty or judgment. Aviation workers need ample rest and their work schedules should include adequate rest periods. Shift-workers should not work for more than four consecutive nights. The schedule should provide them with at least a full day of rest after working two consecutive night shifts. The full day will ensure that they have recovered from any sleep loss experienced.

It is not possible to eliminate fatigue in the aviation industry, but any risks associated with fatigue can be managed. Having a partnership between the flight crew and the operator will assist in managing the risks associated with fatigue. Company policies and practices can cause fatigue to the flight crew and aviation workers. The length of shift, predictability of work schedules, and amount of work performed during the night are some examples of company policies that have an effect on employees' fatigue. Jones, Dorrian, Rajaratnam, & Dawson, 2005()

state that, if a shift is too long, the employees will tire, and they will have to continue working, and this could lead to problems in their work. A company should have predictable schedules. This allows employees to know well in advance their shifts and plan accordingly. Any night shift changes should be communicated at least a week in advance. This will provide the workers with ample time to adjust their work schedules in preparation for the changes.

Due to an employee's circadian clock, a change in work and rest pattern will create conflicting cues to their body Gander, Gregory, Miller, et al., 1998.

The employee's circadian clock will attempt to the new pattern of sleep and work, but exposure to light draws it back to its diurnal orientation. This results in incomplete adaptation and adjustment to the new pattern. This was demonstrated by Gander, Gregory, Connell, et al. (1998)

when analyzing cargo pilots on domestic routes. In 24 hours, the pilots did not cross more than one time zone, and they worked for three or five nights in a row normally. Following this schedule, it was expected that the pilots would completely adapt to the night schedules. The study established that the pilots body temperature only changed by about 2.8 hours.

Employees need training in order for them to recognize when they are fatigued. Educating them on how to manage fatigue and reduce its risks will assist in reducing aviation accidents caused by fatigue. Demonstrating to the employees how they can control the risks associated with fatigue will also be beneficial to the airline Lindgren, Andersson, & Norback, 2006.

Encouraging napping and sleeping during night shifts will assist in preventing fatigue problems. The workers will not struggle to stay awake when they are fatigued, and after their nap, they will feel fresh and relaxed to continue with their work. Alternating the naps is vital to ensure that not all employees nap at the same time. Using external and internal training courses or providing meetings and discussions will assist in educating the employees in regards to fatigue. The employees will gain knowledge in how they can reduce their fatigue levels. Management and rostering staffs need training too on fatigue management. The rostering staffs need to understand how fatigue affects employees and this will allow them to provide the workers with ample rest periods. The rostering staff are charged with making employee schedules, and they need to understand how best to maximize on employee output.