Module 1 - Fatigue


  1. Fatigue is a hazard that affects safety, health and well-being. It presents a considerable risk to safety of life, property, health, security and protection of the marine environment.

  2. This module provides a general overview of fatigue and its causes and consequences. This knowledge is important for developing strategies to reduce the risk of fatigue and related incidents.

  3. It is recommended that all parties become familiar with module 1 prior to using modules 2 to 6.

    Fatigue and life on a ship

  4. There is a common misconception that fatigue "comes with the job"; while not particular to the maritime industry, it is certainly pervasive within it. Fatigue is a hazard and needs to be addressed.

  5. Fatigue is a problem for all 24-hour-a-day transportation modes and industries, including the maritime industry. However, operational aspects associated with the maritime industry are also more complex than those associated with other industries. For example, variety of ship-types, the pattern and length of sea passage, the number of port visits and port rotations, and the length of time a ship remains in port, all present unique combinations of potential causes of fatigue.

  6. The demanding nature of shipping means that:

    .1 seafarers may be required to work long and irregular hours;

    .2 seafarers may spend an extended period of time working and living away from home, on a ship that is subject to unpredictable environmental factors (i.e. changing weather conditions);

    .3 the ship is both a seafarer's workplace and their home while on board; and

    .4 while serving on board the vessel, there may not be a clear separation between work and recreation, which can influence their mental and emotional well-being.

  7. Technology is sometimes seen as a way to improve the efficiency of work systems. However, technology changes the nature of work and alters workload, therefore it is important to evaluate the impact of technological changes on crew workload and consequently fatigue.

    Causes of fatigue

  8. Fatigue is caused by a range of factors, but is primarily caused by:

    .1 lack of sleep, i.e. inadequate restorative sleep;
    .2 poor quality of sleep and rest;
    .3 work/sleep at inappropriate times of the body clock (circadian rhythm);
    .4 staying awake for long periods;
    .5 stress; and
    .6 excessive workload (prolonged mental and/or physical exertion).

  9. There are many ways to categorize the causes of fatigue. To ensure thoroughness and to provide good coverage of most causes, they have been categorized into five general factors:

    .1 seafarer-specific factors;
    .2 management factors (ashore and aboard ship);
    .3 ship-specific factors;
    .4 environmental factors; and
    .5 operational factors.

    Seafarer-specific factors

  10. The seafarer-specific factors are related to lifestyle behaviour, personal habits and individual attributes. Fatigue varies from one person to another and its effects are often dependent on the particular activity being performed.

  11. The seafarer-specific factors include the following:

    .1 sleep and rest:
         .1 quantity, quality and continuity of sleep;
         .2 sleep disorders/disturbances; and
         .3 recovery rest/breaks;

    .2 body clock/Circadian rhythms;

    .3 psychological and emotional factors:
         .1 fear;
         .2 monotony and boredom; and
         .3 loneliness;

    .4 health and well-being:
         .1 diet/nutrition/hydration;
         .2 exercise and fitness; and
         .3 illness and onset of illness;

    5 stress:
         .1 skill, knowledge and training as it relates to the job;
         .2 personal issues of concern in personal life; and
         .3 interpersonal relationships at work or at home;

    .6 medication and substance use:
         .1 alcohol;
         .2 drugs (prescription and non-prescription);
         .3 supplements; and
         .4 caffeine and other stimulants;

    .7 age;

    .8 shift work and work schedules;

    .9 workload (mental/physical); and

    .10 jet lag.

    Management factors (ashore and aboard ship)

  12. Management factors relate to how ships are managed and operated. These factors can potentially cause stress and an increased workload, ultimately resulting in fatigue. These factors include:

    .1 Organizational factors:
         .1 manning policies, levels, and retention;
         .2 role of riders and shore personnel;
         .3 administrative work/reporting/inspection requirements;
         .4 economics;
         .5 duty schedule-shift, overtime, breaks;
         .6 company procedures, culture and management style;
         .7 shore-based support;
         .8 rules and regulations;
         .9 other resources;
         .10 maintenance and repair of the ship; and
         .11 drill schedules and training of crew;

    .2 Voyage and scheduling factors:
         .1 frequency and duration of port calls;
         .2 time between ports;
         .3 routeing;
         .4 weather and sea condition on route;
         .5 traffic density on route;
         .6 nature of duties/workload while in port and at sea; and
         .7 availability of shore leave.

  13. Module 2 provides recommended strategies for identifying, mitigating and controlling fatigue risks due to management factors.

    Ship-specific factors

  14. These factors include some ship features that can affect and contribute to fatigue. Some ship design features affect workload (i.e. automation, equipment design and reliability), some affect the crew's ability to sleep, and others affect the level of physical stress on the crew (i.e. noise, vibration, accommodation spaces, etc.). The following list details some influential ship-specific factors:

    .1 ship design;
    .2 level and complexity of automation;
    .3 level of redundancy;
    .4 equipment design and reliability;
    .5 inspection and maintenance;
    .6 condition of the ship;
    .7 physical comfort in work spaces;
    .8 location of quarters;
    .9 ship motion; and
    .10 physical comfort of accommodation spaces.

  15. Module 5 provides recommended strategies for identifying, mitigating and controlling fatigue risks due to ship-specific factors.

    Environmental factors

  16. Environmental factors within areas in which seafarers live and work (both inside and outside the ship) may contribute to the onset of fatigue, and impact both sleep quantity and quality. Environmental factors to consider include noise and vibration, light, ship motion, temperature and humidity, and ventilation/air exchange. Long-term exposure to some of the following may impact a person's health:

    .1 Noise: (such as main engines, switchboards, TV and conversations) affects the ability to fall asleep, causing sleep loss, or it can alter one's sleep stage or depth of sleep.

    .2 Vibration: may affect sleep and fatigue. For example, alterations in vibration pattern may keep people awake, keep them from advancing into deeper sleep, or wake them up.

    .3 Light: (such as colour, intensity and exposure timing) is a complicated environmental factor. In addition, the use of electronic displays that emit blue light (such as computer screens, flat-screen televisions and smartphones) can also influence the body clock and can delay the onset of sleep, especially when used prior to bedtime.

    .4 Ship motion: depending on the weather and sea conditions, ship motion may interfere with sleep, cause motion-induced fatigue (fatigue caused by the extra energy expended to maintain balance while moving, especially during harsh sea conditions) and seasickness.

    .5 Temperature and humidity: all excessively hot and cold conditions will make an individual feel less alert and generally more fatigued. It is important that the shipboard temperature and humidity is controllable as this affects sleep and alertness. For example, the body sleeps best when the environment temperature is between 18ºC and 24ºC.

    .6 Ventilation/air exchange: in addition to controlling temperature and humidity, air quality (e.g. noxious odours or stale air) and design/placement of the ventilation system may interfere with sleep.

    Operational factors

  17. While seafarers, companies, Administrations and port State authorities are the primary actors, many other stakeholders may also have an impact on shipboard operations and workload. Aspects to consider include inspections, surveys, audits, visits, reporting, security measures and any other additional tasks to be performed on board. Therefore, other stakeholders should contribute to the mitigation of fatigue by considering the impacts of their actions on shipboard operations.

  18. Opportunities to mitigate the effects of these factors vary and will be discussed further in subsequent modules.

    Important basic concepts in understanding fatigue

  19. This section highlights some of the important concepts that provide an overall understanding about fatigue. The most significant aspects of fatigue are:

    .1 sleep;
    .2 body clock and the circadian rhythm;
    .3 time awake;
    .4 jet lag;
    .5 workload;
    .6 stress;
    .7 health; and
    .8 individual differences.


  20. Not all sleep has the same quality or provides the same recuperative benefits. In order to satisfy the needs of the human body, sleep must have three characteristics to be most effective:

    .1 Quantity: it is generally recommended that a person obtain, on average, seven to eight hours of good quality sleep per 24-hour period. To perform adequately and effectively, a person needs the amount of sleep that produces the feeling of being refreshed and alert. Alertness and performance are directly related to sleep. Insufficient sleep will impair alertness. Only sleep can maintain or restore performance levels.

    .2 Quality: sleep is a highly organized sequence of events that follows a regular pattern of cycles between light and deep sleep. People need deep sleep. Deep sleep is a very restorative phase of sleep.

    .3 Continuity: sleep quality is dependent upon unbroken cycles of sleep, meaning sleep needs to be uninterrupted in order to retain its restorative value. Six 1-hour naps do not have the same benefit as one 6-hour period of sleep. The more fragmented the sleep cycle, the less restorative sleep becomes. This results in continued feelings of tiredness and often impacts performance and decision-making. If the time of sleep is out of synchronization with a person's body clock, it is difficult to sleep properly. It should be noted that the proportion of time spent in deep sleep decreases as we get older. Sleep also becomes more fragmented as we get older.

  21. Many factors contribute to sleep disruption and poor sleep quality; some are within our control while others are not:

    .1 environmental factors;
    .2 food;
    .3 medication and substance use;
    .4 psychological factors;
    .5 sleep disorders; and
    .6 operational factors.

  22. Sleep debt is "insufficient accumulated sleep over multiple consecutive 24-hour periods". For example, if an individual needs eight hours of sleep per 24-hour period and only obtains six hours, they have accumulated a sleep debt. Sleep debt will affect an individual's level of alertness and performance. Long-term sleep debt may also lead to health problems. Over time, sleep-deprived individuals may become less aware of just how fatigued they are and become unable to judge their own level of performance.

  23. When someone is woken up suddenly, the brain can have difficulty transitioning out of deep sleep. This is known as sleep inertia. Sleep inertia causes feelings of grogginess and disorientation, with impaired short-term memory and decision-making, and can last longer than 30 minutes. Sleep inertia can also occur following lighter sleep, but it tends to be longer and more disorienting when someone is woken abruptly out of deeper sleep.

    Body clock and the circadian rhytm

  24. The time of day in which work takes place is a key risk factor in determining fatigue. This is because, independent of prior sleep and wakefulness, humans are biologically programmed to be active during the day and to sleep at night.

  25. Each individual has a body clock, and this clock regulates the body's circadian rhythm. Our bodies move through various physical processes and states within a 24-hour period, such as sleeping/waking, and cyclical changes in body temperature, hormone levels, sensitivity to drugs, etc. This cycle represents the circadian rhythm. The body clock is synchronized to the traditional pattern of daytime wakefulness and night-time sleep.

  26. The body clock makes a person sleepy or alert on a regular schedule whether they are working or not. In normal conditions, the sleep/wake cycle follows a 24-hour rhythm; however, the cycle is not the same for everyone.

  27. Independent of other factors, fatigue is most likely, and when present, most severe, in the early hours of the morning, coinciding with the strongest drive for sleep. This period typically occurs between the hours of 3 and 5 a.m. and is commonly referred to as the window of circadian low (WOCL).

  28. In general, seafarers working through the night may be at a higher risk of fatigue and have to make additional effort to maintain alertness and performance. This is supported by maritime studies and investigations in which fatigue was found to be a contributing cause in incidents that mainly occurred between midnight and 6 a.m. This indicates that from a maritime perspective high risk times may fall between these hours.

  29. Apart from the WOCL, another distinct dip occurs between 3 and 5 p.m. (best known as the post-lunch dip).

  30. The states of sleep/wakefulness and circadian rhythms interact in several ways:

    .1 The two can work against each other and thereby weaken or negate each other's effect. For example, a well-rested person is still affected by a circadian low point; conversely, a person who is sleep-deprived may feel a momentary increase in alertness due to a peak in circadian rhythm.

    .2 The two can also work in the same direction, thereby intensifying the effect they each have on a person's level of alertness. For example, when someone is sleep-deprived, a circadian low point will further exacerbate the feeling of sleepiness.

  31. For many seafarers, working patterns conflict with their body clock. Irregular schedules caused by shifting rotations, crossing time zones, etc. cause the circadian rhythms to be out of synchronization. As circadian adjustment to a particular pattern of work and rest is a relatively slow process (only adjust by an hour or two each day), constant changes impair sleep. Work that requires seafarers to be awake and working at night or early morning or to work for extended periods can cause disruptions to the body clock resulting in increased fatigue.

  32. Even though the body clock can be reset over time, such as when changing times zones for an extended period, research shows that it cannot be permanently adjusted to a reversed cycle of work and sleep. Because the body clock may not adapt fully to altered sleep/wake patterns:

    .1 seafarers who work through the night can be expected to be sleepy and have to make additional effort to maintain alertness and performance; and

    .2 some seafarers may be fatigued at the start of their work period, as they adapt to their sleep routine.

    Time awake

  33. How long an individual is awake affects sleepiness and consequently fatigue levels. The longer an individual has been awake, the poorer their performance. In general, the longer a seafarer remains awake, the stronger the drive for sleep, and the higher the levels of fatigue. During the first hours awake, the urge to sleep may go unnoticed, but as the amount of continuous wakefulness approaches 16 hours, awareness of the pressure to sleep is highly likely. This occurs sooner if the seafarer is already suffering from sleep debt.

  34. Alertness and performance levels begin to decrease after a number of hours awake, with long duty periods associated with higher levels of fatigue than shorter duty periods due to extended wakefulness and demands on attention. In addition, the longer an individual has continuously been on a task without a break, the more likely they will be fatigued. Accident rates rise exponentially after 12 hours of consecutive work, particularly when working at night.

  35. Long work hours are associated with poor performance, higher injury rates, and poorer safety and/or health outcomes (both mental and physical). Another important aspect to consider are work commutes. Many seafarers may be required to travel or drive long distances to the ship and then have to work.

    Jet lag

  36. Jet lag occurs following long flights through several time zones. Seafarers crossing time zones to join their ship are exposed to a sudden change in the day/night cycle causing circadian disruption. It is a condition that causes fatigue in addition to sleep deprivation and irritability. The body clock will eventually adapt to a new time zone; however, depending on the new schedule, it takes several days to adjust. During the period of adaptation to the new time zone, common symptoms include wanting to eat and sleep at times that are out of step with the local routine, problems with digestion, degraded performance on mental and physical tasks, and mood changes. It is easier to adjust while crossing from east to west than from west to east.


  37. Workload refers to the type and intensity of tasks performed. Fatigue can occur when workload is either very high or very low. High and low workload may be present in a shipboard work environment, and are likely to induce fatigue. Fatigue resulting from workload becomes an increasing concern when combined with long periods of wakefulness and long duty hours.

    .1 High workload: both high physical workload and high mental workload (such as tasks with excessive demands on attention) may lead to fatigue. Examples of high workload routinely experienced on board ships include, but are not limited to, navigating in congested and dangerous waters; frequent port calls; navigating in conditions of poor visibility and/or bad weather; entering and exiting a port/harbour; having to complete multiple tasks; and tank cleaning and cargo operations.

    .2 Low workload: monotonous tasks, such as monitoring (of engine-room displays for example) can result in loss of interest and boredom, which also increases the effects of fatigue. This can be a particular problem when conducting bridge or engine monitoring and vigilance tasks across long periods of time. This can be readily seen when a person is required to maintain a period of concentrated and sustained attention, especially during the night (night duty, for example). People are generally not good at long duration vigilance tasks. Performance and alertness is further impacted if vigilance and monitoring tasks need to be carried out during the night-time hours, specifically between midnight and 5 a.m.


  38. Stress occurs when a person is confronted with an environment or situation that poses a threat or demand, and the individual becomes aware of his or her inability to cope or difficulty in coping with the environment (a feeling of being overwhelmed). This can result in reduced work performance and health problems. Stress is influenced by many characteristics of the work environment or issues with or changes to personal, family, or home environment. Stress can be caused by a number of factors, including:

    .1 environmental factors (e.g. constant or irregular noise, vibration, temperatures, weather, ice conditions);
    .2 personal circumstances (e.g. family problems, home sickness, isolation);
    .3 inadequate restorative sleep;
    .4 broken or interrupted sleep or rest periods;
    .5 excessive working hours;
    .6 intense mental and/or physical workload; and
    .7 onboard interpersonal relationships

  39. These stressors, and others, can impact the extent to which a seafarer is able to acquire sufficient sleep and consequently lead to fatigue. For example, family aspects that require attention but are beyond the seafarer's control may lead to short sleep duration and extended wakefulness. Seafarers may be away from home for extended periods of time. Loneliness, isolation, family conflict and concern about family members may provide enough stress to be considered risk factors.


  40. Healthy lifestyle choices such as good physical fitness and a healthy diet have been reported to reduce fatigue and improve alertness and performance. Conversely, unhealthy lifestyle choices can negatively impact sleep and therefore contribute to fatigue.

    .1 Nutrition: a poor diet that does not include fresh fruit and vegetables can contribute to fatigue by adversely affecting a seafarer's health. In addition, irregular meal times can adversely affect digestion, which also follows the circadian rhythm. Digestion is programmed to be most efficient during the day and much less so at night. Food eaten at night is digested at a slower rate. This can often lead to feeling bloated or constipated and can cause heartburn and indigestion. Gastrointestinal upsets are very common in people who eat outside of traditional meal times. These upsets can be made worse by drinking tea, coffee or alcohol. Additionally, when lying down right after eating a large meal, acid reflux may occur. Night workers are 5 times more likely to get peptic ulcers than day workers.

    .2 Hydration: dehydration is also a factor that contributes to fatigue. When the body is low on water, it tries to conserve what it has left. It does this by reducing activity and making the body relax and slow down. When relaxed, people have a higher chance of falling asleep. Being dehydrated can also make people feel light-headed and cause headaches. In addition to maintaining cognitive function and alertness, drinking adequate water helps keep the digestive and circulatory systems operating properly. Water brings healthy nutrients to cells and carries away toxins.

    .3 Exercise and fitness: poor physical fitness adversely affects overall health and causes people to tire easily. Exercise speeds up metabolism and increases blood flow, which helps to keep a person awake. Exercise also helps the body cope with stress and can help individuals suffering from depression, a condition that can be characterized by fatigue. Physical exercise can also help reduce a person's susceptibility to certain diseases and infections. The inability to exercise is considered a risk factor because it is a circumstance that takes away a crew member's ability to increase physical fitness, enhance sleep, think clearly and manage stress.

    .4 Caffeine and other stimulants: caffeine can be found in beverages such as coffee, tea and some soft drinks. Caffeine can improve alertness and concentration in moderate doses, but it is not a substitute for adequate sleep and rest. Too much caffeine can have harmful effects such as increased heart rate and blood pressure, and can cause fatigue in some people. It takes caffeine about 15 to 30 minutes to enter the body's system, and its physiological effects peak about an hour after the drug reaches the bloodstream. The effects of caffeine can vary highly from individual to individual and depend on physical condition, age, level of sleep debt, frequency of use and time of day. Generally, caffeine levels drop by half every five or six hours. Its effects can last long after consumption and may interfere with needed sleep. Caffeine shortens total sleep time by preventing sleep. Caffeine consumption can also cause dehydration.

    .5 Alcohol: although alcohol is a central nervous system depressant, it can impair the quality of sleep. Alcohol can lead to increased sleepiness and reduced alertness, even after the alcohol is no longer detectable. There are also serious health consequences related to the long-term abuse of alcohol. Many shipping companies have "zero alcohol tolerance."

    .6 Nicotine: nicotine is highly addictive and the dangers to health are well documented. Nicotine users generally have more disturbed sleep, typically taking longer to fall asleep and experiencing more wake time during a sleep period.

    .7 Drugs: it is important for seafarers to be aware of how drugs and supplements may affect their health and their sleep-wake cycles. Drug effects vary not only from person to person, they can also vary for the same person depending on time of day, mood, tiredness and the amount of food eaten. In addition, there are other drugs prescribed for specific ailments that can have sedating side effects. Some prescription drugs can affect people's ability to operate machinery (induce sleepiness). They may also interact with existing fatigue levels and other drugs (including alcohol) and supplements, further affecting performance. Some over-the-counter drugs used for pain relief or colds and flu may increase drowsiness and fatigue-related symptoms.

    .8 Supplements: there are now a number of nutritional supplements, natural products and energy drinks that are available on the market that directly influence sleep/wake states. Just because they are sold over the counter does not mean they are safe or appropriate for everyone. These products may interact with prescription or over-the-counter drugs to further affect performance. Individuals should proactively seek advice and guidance from their healthcare providers before using these products to learn about their appropriate use.

    .9 Sleep disorders: other health-related aspects are the wide variety of sleep disorders, which are known to disrupt the quality of sleep and make restorative sleep impossible, even when individuals spend enough time trying to sleep. The most common sleep disorders are obstructive sleep apnoea, insomnia, restless legs syndrome, shift work sleep disorder and narcolepsy. Undiagnosed or untreated sleep disorders can cause sleepiness problems. Sleep disorders pose a particular risk for seafarers, especially as maritime operations already expose seafarers to restricted sleep. Large numbers of individuals suffering from sleep disorders are unaware of and have not been diagnosed or treated for their disorder.

    .1 Obstructive sleep apnoea (OSA) results in breathing being interrupted during sleep. Repetitive episodes of non-effective breathing, very shallow breaths or inadequate breaths lead to frequent partial arousals from sleep, resulting in ineffective sleep and sleep debt. OSA is a potentially serious sleep disorder resulting in excessive daytime sleepiness and can lead to cardiovascular problems. Sleep apnoea, which may be indicated by loud snoring with pauses of silence, often goes undiagnosed and untreated and has been known to be a contributing factor to incidents in all modes of transportation. Some risk factors include excessive weight, high body mass index (BMI), high blood pressure, smoking and diabetes.

    .2 Insomnia is the most prevalent sleep disorder and is characterized by an inability to fall asleep and/or by waking up during the night and having difficulty going back to sleep. Long-term insomnia is more common in women than men and tends to increase with age. Short-term insomnia may be caused by emotional or physical discomfort, stress, environmental noise, extreme temperatures or jet lag, or may be the side effect of medication. Secondary insomnia may result from a combination of physical or mental disorders, undiagnosed or uncontrolled sleep disorders and effects of prescription or non-prescription medications.

    .3 Restless legs syndrome (RSL) is a movement disorder that is often associated with a sleep complaint. People with RLS have unpleasant leg sensations and an almost irresistible urge to move their legs. Symptoms are worse during inactivity and often interfere with sleep. Sitting still for long periods becomes difficult; symptoms are usually worse in the evening and night and less severe in the morning.

    .4 Shift work sleep disorder is characterized by insomnia and excessive sleepiness affecting people whose work hours overlap with the typical sleep period. There are numerous shift work schedules (permanent, intermittent or rotating); consequently, the manifestations of this disorder are quite variable. Those with shift work disorder complain more of mood problems such as impatience and depression, as well as more self-reported health complaints such as ulcers and substance use.

    .5 Narcolepsy is a chronic sleep disorder that usually becomes evident during adolescence or young adulthood. The main characteristic of narcolepsy is excessive and overwhelming daytime sleepiness (even after adequate night-time sleep). A person with narcolepsy is likely to become drowsy or to fall asleep at inappropriate times and places, and in extreme cases during periods of activity. Daytime sleep attacks may occur without warning and may be irresistible. In addition, night-time sleep may also be fragmented.

    Individual differences

  41. Individuals respond to fatigue differently and may become fatigued at different times, and to different degrees of severity, under the same circumstances. There are also individual characteristics related to circadian rhythms. People can be characterized as morning or evening types depending on the period of the day when they perform at their best.

    Effects of fatigue

  42. When a person is affected by fatigue, performance on the job can be significantly impaired. Impairment will occur in every aspect of human performance (physically, emotionally, and mentally) such as in decision-making, response time, judgement, hand-eye coordination and countless other skills. When impairment due to fatigue, such as impaired memory or poor communication, coincides with other risks in the environment, incidents can result. This is evidenced in a number of maritime casualties in which fatigue was a contributory factor. Maritime studies have also confirmed the association between fatigue and poor performance.

  43. People are poor judges of their own level of fatigue, performance and decision-making. The following is a sample of fatigue's known effect on performance:

    .1 Fatigued individuals become more susceptible to errors of attention and memory (for example, it is not uncommon for fatigued individuals to omit steps in a sequence).

    .2 Fatigued individuals will often select strategies that have a high degree of risk on the basis that they require less effort to execute.

    .3 Fatigue can negatively affect an individual's ability to identify and respond to stimuli.

    .4 Fatigue can also negatively affect problem-solving, which is an integral part of handling new or challenging tasks.

  44. Particularly dangerous situations at sea arising from sleep debt are brief, uncontrolled and spontaneous sleep episodes while working, termed microsleeps. During a microsleep, the brain disengages from the environment (it stops processing visual information and sounds). Sleep deprivation, which is caused by cumulative sleep debt, can make people more susceptible to microsleeps. The likelihood of microsleeps is even greater if the individual is on duty during a circadian low.

  45. The range of effects and signs of fatigue can typically be grouped into three categories: cognitive (e.g. loss of vigilance), physical (e.g. yawning, micro-sleeps) and behavioural (e.g. irritability, mood). The table below outlines some of the major symptoms under each category; however, it is not inclusive. Additionally, many of these symptoms may be subtle.

    Table 1: Effects of fatigue

    Inability to concentrate
    • Unable to organize a series of activities
    • Preoccupied with a single task
    • Focuses on a trivial problem, neglecting more important ones
    • Reverts to old but ineffective habits
    • Less vigilant than usual
    • Decline in ability to solve complex problems
    • Lapses of attention
    • Difficulty in multitasking
    Diminished decision-making ability
    • Misjudges distance, speed, time, etc.
    • Fails to appreciate the gravity of the situation
    • Overlooks items that should be included
    • Chooses risky options
    • Greater indecisiveness
    Poor memory
    • Fails to remember the sequence of task or task elements
    • Difficulty remembering events or procedures
    • Forgets to complete a task or part of a task
    • Memory lapses
    Slowing of cognitive processes
    • Responds slowly (if at all) to normal, abnormal or emergency situations
    Involuntary need to sleep
    • Slow eyelid closures
    • Droopy eyelids
    • Itchy eye
    • Nodding off
    • Inability to stay awake
    Loss of control of bodily movements
    • Affected speech, e.g. it may be slurred, slowed or garbled, or hard to find the right words
    • Feeling heaviness in the arms and legs
    • Clumsiness, such as increased frequency of dropping objects like tools or parts
    • Difficulty with hand-eye coordination skills (such as switch selection)
    • Tremors
    Health Issues
    • Headaches
    • Giddiness
    • Rapid breathing
    • Digestion problems
    • Leg pains or cramps
    • Insomnia
    • Sudden sweating fits
    • Heart palpitations / irregular heart beats
    • Loss of appetite (and sometimes an increase in unhealthy eating habits)
    Mood change
    • Quieter, less talkative than usual
    • Unusually irritable
    • Decreased tolerance and anti-social behaviour
    • Depression
    Attitude change
    • Fails to anticipate danger
    • Fails to observe and obey warning signs
    • Seems unaware of own poor performance
    • More willing to take risks
    • Ignores normal checks and procedures
    • Displays a "don't care" attitude
    • Less desire to socialize
    • Increasing omissions and carelessness
    • Low motivation
  46. Sleep debt, over long periods of time (more than two weeks), has long-term effects on health and clinical illnesses, increasing the risks of pain, stress, obesity, coronary heart disease, gastrointestinal disorders and diabetes. Long-term effects also point to mental health problems such as negative mood states and depression.

  47. Fatigue is known to affect performance and reduce individual and crew effectiveness and efficiency, decrease productivity, lower standards of work, and may lead to errors. The instances of injuries and incidents reportedly related to fatigue within maritime operations have resulted in great economic, environmental and human cost. Thus, addressing the risks of fatigue and its causes is essential.

    ILO and IMO instruments related to fatigue

  48. The following IMO instruments contain guidance on fatigue-related aspects:

    .1 International Convention on Standards of Training Certification and Watchkeeping for Seafarers (STCW), 1978, as amended

    .1 Regulation VIII/1 (Fitness for duty) states that "each Administration shall, for the purpose of preventing fatigue:

         .1 establish and enforce rest periods for watchkeeping personnel and those whose duties involve designated safety, security and prevention of pollution duties in accordance with the provisions of section A-VIII/1 of the STCW Code; and

         .2 require that watch systems are so arranged that the efficiency of all watchkeeping personnel is not impaired by fatigue and that duties are so organized that the first watch at the commencement of a voyage and subsequent relieving watches are sufficiently rested and otherwise fit for duty."

    .2 Regulation VIII/2 (Watchkeeping arrangements and principles to be observed) states that "Administrations shall direct the attention of companies, masters, chief engineer officers and all watchkeeping personnel to the requirements, principles and guidance set out in the STCW Code which shall be observed to ensure that a safe continuous watch or watches appropriate to the prevailing circumstances and conditions are maintained on all seagoing ships at all times."

    .3 In addition, part A of the STCW Code sets minimum periods and frequencies of rest and requires that watch schedules be posted where they are easily accessible.

    .2 International Safety Management (ISM) Code: This Code introduces safety management requirements on ship companies to assess all identified risks (both ashore and afloat) that affect safety (to ship and personnel) and environment and establish appropriate safeguards. The fatigue-related requirements include the requirement for the company to:

    .1 develop, implement and maintain a safety management system (section 1.4);

    .2 ensure that each ship is manned with qualified, certificated and medically fit seafarers in accordance with national and international requirements and is appropriately manned in order to encompass all aspects of maintaining safe operations on board (paragraph 6.2);

    .3 ensure necessary shipboard support is provided so that the master's duties can be safely performed (paragraph 6.1.3); and

    .4 provide familiarization and training for shipboard personnel (paragraphs 6.3, 6.4 and 6.5).

    .3 Principles of minimum safe manning (resolution A.1047(27)): This resolution provides guidelines for determining minimum safe manning. In particular in ensuring "fitness for duty", paragraph 1.4.2 of annex 2 states that "in determining the minimum safe manning of a ship, consideration should also be given to the capability of the master and the ship's complement to coordinate the activities necessary for the safe operation and for the security of the ship and for the protection of the marine environment."

    .4 Fatigue factors in manning and safety (resolution A.772(18)): This resolution provides a general description of fatigue and identifies the factors of ship operations which may contribute to fatigue.

  49. The following ILO instrument contains guidance on fatigue-related aspects:

    .1 Maritime Labour Convention (MLC), 2006. Relevant aspects of the MLC include, but are not limited to:

    .1 Regulation 2.3: To ensure that seafarers have regulated hours of work or hours of rest.

    .2 Regulation 2.4: To ensure that seafarers have adequate leave.

    .3 Regulation 2.7: To ensure that seafarers work on board ships with sufficient personnel for the safe, efficient and secure operation of the ship.

    .4 Regulation 3.1: To ensure that seafarers have decent accommodation and recreational facilities on board.

    .5 Regulation 3.2: To ensure that seafarers have access to good quality food and drinking water provided under regulated hygienic conditions.

    .6 Regulation 4.3: To ensure that seafarers' work environment on board ships promotes occupational safety and health.


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