  E
INTERNATIONAL  MARITIME ORGANIZATION
  4 ALBERT EMBANKMENT LONDON SE1 7SR

  Telephone:  020 7735 7611
  Fax:	020 7587 3210
  Telex:	23588 IMOLDN G	IMO

 Ref. T2/4.2	MSC/Circ.1014
           12 June 2001



                 GUIDANCE ON FATIGUE MITIGATION AND MANAGEMENT


1 The Maritime Safety Committee (MSC), at its seventy-first session (19 to 28 May 1999), considered the issue of human fatigue and the direction where IMO efforts should be focused. In this regard, it was agreed that practical guidance should be developed to provide appropriate information on fatigue to all parties concerned. This guidance should inform each party that has a direct impact on vessel safety (naval architects, owners/operators, masters, officers, ratings, training institutions, etc.) of the nature of fatigue, its causes, preventive measures and countermeasures.

2 Accordingly, the MSC, at its seventy-fourth session (30 May to 8 June 2001), approved the annexed guidelines, composed of self-contained Modules, each addressing a different party. The Modules have been assembled using existing information, in a useful format, for transmission to the different parties who have a direct impact on vessel safety.

3        Member Governments are invited to:

       .1 bring the attached guidelines to the attention of their maritime Administrations and relevant industry organizations and to all other parties who have direct impact on ship safety;

       .2 use this guidance as a basis for developing various types of tools for dissemination of the information given in the guidelines (such as: pamphlets, video training modules, seminars and workshops, etc.); and

       .3              take the guidelines into consideration when determining minimum safe manning.

4 Shipowners, ship operators and shipping companies are strongly urged to take the issue of fatigue into account when developing, implementing and improving safety management systems under the ISM Code.


                                      ***
                                       






                                    GUIDELINES ON FATIGUE INTRODUCTION
 Fatigue is a major human element hazard because it affects most aspects of a seafarer's ability to do their job effectively and safely. Importantly, fatigue affects everyone regardless of skill, knowledge and training. The effects of fatigue are particularly dangerous in the shipping industry.  The technical and specialized nature of this industry requires constant alertness and intense concentration from its workers.

 Fatigue can be defined in many ways. However, it is generally described as a state of feeling tired, weary, or sleepy that results from prolonged mental or physical work, extended periods of anxiety, exposure to harsh environments, and/or loss of sleep. The result of fatigue is impaired performance and diminished alertness.

 Fatigue is caused by a range of factors but is primarily affected by inadequate restorative sleep, excessive wakefulness, workload and work/sleep at inappropriate times of the body clock (circadian cycle). In twenty-hour hour continuous operations such as the maritime industry these are common factors. As a result, the management of fatigue is a significant priority for the maritime industry.

 
 Several studies have shown that seafarers in general:
   * obtain one to three hours less sleep per day when on the ship compared to when at home; 
   * are exposed to fragmented sleep patterns;
   * are not provided with sufficient rest times when in port; and
   * endure poor environmental conditions in sleeping spaces. 

 The maritime industry operates a variety of work schedules in a wide range of operational environments. From coastal operations through to remote blue waters, the work schedules, work type, location, demographics and work/rest environment vary from ship to ship.
 
 Effectively dealing with fatigue in the marine environment requires a holistic approach. There is no one-system approach to addressing fatigue, but there are certain principles (e.g. duty schedules, lifestyle habits, rest, medication, workload.) that must be addressed in order to gain the knowledge and the understanding to manage this issue. The aim of these guidelines is to provide that information in a readily accessible format for interested parties. The tools and systems contained in this document can be tailored to suit a range of operations. The objective is to minimise the incidence and consequences of fatigue. To minimize the incidence and consequences of fatigue.

Objective

 

 To assist in the development of a marine safety culture by addressing the issue of fatigue, the International Maritime Organization (IMO) has developed practical guidance to assist interested parties to better understand and manage the issue of fatigue.

 The philosophy behind the development of the guidance was not to develop new information but rather assemble and update what already exists, in a useful format, for transmission to those parties who have a direct impact on ship safety.

 The outline of the information is related to the potential dangers associated with fatigue and ultimately the effect on the health and safety of the personnel working on ships , security and the protection of the enviroment. The guidelines contain information on the symptoms and causes of fatigue, and address solutions to control and manage the risks of   fatigue to improve the associated health problems and help prevent a fatigue related incidents from occurring.

 Organization
 
 As shown in figure 1, the guidelines are composed of Modules each devoted to an interested party. The modules are as follow:
 
1. guidelines are composed of Modules each devoted to an interested party. The modules are as follows: 1.
  Module 1
     Fatigue  -  Causes and Consequences
2.
  Module 2
     Fatigue and the Company
3.
  Module 3
     Fatigue and the Seafarer

  
     
4.
  Module 4
     Fatigue and Training 


     

  
     
5.
  Module 5
     Fatigue and Ship Design
6.
  Module 6
     Fatigue and the Administration

  
     
7.
  Appendix
     Fatigue Tools


                                       
 Figure 1: Organization of the Guidelines on Fatigue

 How to use these modules 
 
 Although all Modules are self-contained, it is recommended that all parties become familiar with Module 1, which contains general information on fatigue. In other instances it will be beneficial if the reader (interested party) becomes familiar with Modules other than the immediately applicable one.

 It is strongly suggested that maximum benefit will be derived from the integration of this material into:
       oo Safety management systems under the ISM Code;
       oo Corporate management systems, such as medical, human resources, etc.;
       oo Training, particularly management oriented and those required by the STCW code;
       oo Accident investigation processes and methodologies; and
       oo Manning determinations,  when considered in conjunction with the manning requirements (IMO Resolution A.1047(27) Principles of Minimum Safe Manning).


 Future work 
 
 These Guidelines are a living document. They should be updated periodically as scientifically validated research reveals new information and new methods are uncovered to deal with the issue of fatigue. Further, the present structure  -  self-contained Modules  -  allows for the creation of new Modules directed to other interested parties.

                             Guidelines on Fatigue

Definitions

Acute fatigue:  Insufficient sleep accrued within a single 24 hr. period.

Chronic fatigue: sleepiness and performance impairment that accumulates when sleep is restricted day after day.

Body clock / Circadian rhythms: Physical, mental and behavioral changes that follow a roughly 24-hour cycle, responding primarily to light and darkness in a person's environment. 


Company: [Owner/Operator/Manager] means the Owner of the ship or any other organization or person such as the Manager, or the bareboat Charterer, who has assumed the responsibility for operation of the ship from the Shipowner (Section 1.1.2 of ISM Code)

Duty: any tasks that shipboard personnel are required to perform, including but not limited to shipboard duties, watchkeeping, drills, maintenance, training, administrative work, loading and unloading.

Duty hours: The number of hours on duty which starts when personnel report for or commence a duty and ends when they are free from all duties.

Ergonomics [Human Factors]: The scientific discipline concerned with the application of validated scientific research about people, their abilities, characteristics and limitations to the design of systems they use, environments in which they function and interact, and jobs they perform to optimize human well-being and overall system performance.

Fatigue: A reduction in physical and/or mental capability as the result of [inadequate sleep, excessive wakefulness, long working hours], physical, mental and/or emotional exertion which may impair nearly all physical and mental abilities including strength, speed, reaction time, coordination, decision making, and/or balance. 

Fatigue risk management: The management of fatigue in a manner appropriate to the level of risk exposure and the nature of the operation, in order to minimize the adverse effects of fatigue on the safety of operations.


Recovery sleep: Sleep required for recovery from the effects of cumulative sleep debt (over multiple consecutive 24-hour periods). Sleep debt is not recovered hour-for-hour. Two nights of unrestricted sleep is typically required for recovery of normal sleep function.

Rest period:  A continuous and defined period of time, subsequent to and/or prior to duty, during which personnel are free of all duties. 

Sleep quality: Capacity of sleep to restore waking function. 

Travel time:  time that cannot be considered rest.


Sleep debt: insufficient accumulated sleep over multiple consecutive 24-hour periods. 


Sleep Inertia:  feelings of grogginess and disorientation, with impaired short-term memory and decision-making. Sleep inertia can occur coming out of lighter sleep (nap), but it tends to be longer and more disorienting when someone is woken abruptly out of slow-wave sleep (deeper sleep).  


Jetlag:   A temporary sleep disorder. It occurs when the body's internal clock is out of sync with cues from a new time zone. Cues can include light exposure and eating times. Fatigue and difficulty concentrating are symptoms.


Fatigue Management System: ?





                                   

                                        
 

 

 

 

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                                   Guidelines on Fatigue Module 1

                                    FATIGUE

 1. Introduction

 For many years, fatigue was discounted as a potential cause of or contributor to human error. One reason for this misunderstanding was the old myth that fatigue could be prevented by various characteristics: personality, intelligence, education, training, skills, compensation, motivation, physical size, strength, attractiveness, or professionalism. However, recent accident data and research point to fatigue as a cause of and/or contributor to human error precisely because of its impact on performance. 
 
 
 

 Fatigue presents a considerable risk to security, the health and safety of human life, damage to the environment, and property. 
 Due to the human, environmental and economic costs associated with fatigue-related incidents, it is the obligation of all stakeholders (seafarers, ship owners, operators and/or managers, ship designers and administrations) to systematically and effectively manage fatigue-related risk.

 This module provides a general overview of fatigue, its causes, and its potential effects on seafarers. This knowledge is helpful in developing mitigation and control strategies to reduce the risk of fatigue and related incidents. The key issue addressed within this module is that fatigue is a fundamental problem for the maritime industry as it detrimentally affects performance at work.
 
 It is recommended that all parties become familiar with Module 1 prior to using Modules 2 to 6.
 


 2. Defining fatigue

 There is no universally accepted technical definition for fatigue. However, common to all the definitions is degradation in human performance. The following definition can be used: 

"A reduction in physical and/or mental capability as the result of [inadequate sleep, excessive wakefulness, long working hours and], physical, mental or emotional exertion which may impair nearly all [mental and] physical abilities including strength, speed, reaction time, coordination, decision making, and/or balance."
 
 
 3. Fatigue and life on a seagoing ship

 Fatigue is a problem for all 24-hour a day transportation modes and industries, the marine industry included. 
 

 The increasingly intensive and demanding nature of shipping means that seafarers may be required to work long and irregular hours in less than ideal conditions.  Principle among these is that the seafarer is a captive of the work environment.  There are also unique aspects of seafaring that separate the marine industry from the others. 
 First, a seafarer spends an average of three to six months working and living away from home, on a moving vessel that is subject to unpredictable environmental factors (i.e. changing weather conditions). Second, while serving on board the vessel, there is no clear separation between work and recreation. Third, today's crews  comprise seafarers from various nationalities and backgrounds who are expected to work and live together for long periods of time. The operational aspects associated with shipping are also more complex compared with standard 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.

 Increasingly complex technologies have also had an influence on ship operations and subsequently fatigue at sea. Technology is sometimes seen as a way to improve efficiency of work systems or to reduce crew numbers. However, technology generally does not reduce work but merely changes it. Unfortunately, implementation or changes often occur with very little evaluation or regard to the impact on the socio-technical system or the seafarers themselves. Technological developments, for example have resulted in quick turn-around times with most ships spending less than 24 hours in port and pressure to reduce this further. This means that `time in port' which used to last for a few days or more and was traditionally used by crew as recovery time is now no longer available. In many cases crew are expected to unload/load a vessel, prepare the vessel to sail and then sail within a very short time frame. The literature suggests that Observations point to the fact that fatigue levels are usually worse on departure than on arrival with most shipboard crew having to sail the vessel irrespective of whether they have had adequate rest. Maritime casualties have clearly demonstrated the consequences of sailing with crews suffering from fatigue. 

 There are also certain cultural obstacles that need to be addressed. Most commonly, seafarers are willing to work whilst highly fatigued because it is seen as `professional' to do so. The widely held belief that fatigue `comes with the job', whilst not particular to the maritime industry is certainly pervasive within it, making it difficult for seafarers to recognise fatigue as a problem and to take appropriate action.

 Hence, an understanding of both the causes and consequences of fatigue as highlighted in this module should enable the company, seafarers, maritime training institutes, administrations and ship designers and naval architects to design and implement more effective systems to manage fatigue-related risks.

 4. Causes of fatigue

 
    * 
    * 
    * 
    * 

 The most common causes of fatigue known to seafarers are lack of sleep, poor quality of rest and sleep, stress and excessive workload. There are many other contributors as well, and each will vary depending on the circumstance (i.e. operational, environmental, individual differences).

 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 4 general factors.

       oo Crew-specific factors
       oo Management factors (ashore and aboard ship)
       oo Ship-specific factors
       oo Environmental factors

 A.  Crew-specific factors

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

 The Crew-specific factors include the following:
 oo        Sleep and Rest
       oo Duration, quantity and quality of sleep
       oo Sleep disorders/disturbances
       oo Recovery Rest breaks
    oo Body Clock/Circadian Rhythms
    oo        Psychological and emotional factors
       oo Fear
       oo Monotony and boredom
    oo Health and well-being
       oo Diet/Nutrition/Hydration
       oo Exercise and fitness
       oo Illness
       oo Alcohol
       oo Drugs and supplements (prescription and non-prescription)
       oo Caffeine and other stimulants
       Health
   oo             Diet
   oo             Illness
    oo        oo        

    oo Stress
       oo Skill, knowledge and training as it relates to the job
       oo Personal problems
       oo Interpersonal relationships

             Ingested Chemicals 
   oo             Alcohol
   oo             Drugs (prescription and non-prescription)
   oo             Supplements 
   oo             Caffeine and other stimulants
       oo           


    oo 
    oo Age
    oo Shiftwork and work schedules
    oo Workload (mental/physical)
    oo Jet lag

 B. Management factors (ashore and aboard ship)

 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
       oo Staffing policies and retention
       oo Role of riders and shore personnel
       oo Paperwork requirements
       oo Economics
       oo Duty schedules-shift, overtime, breaks
       oo Company culture and management style
       oo Rules and regulations
       oo Resources
       oo Upkeep of vessel
       oo Training and selection of crew

    2.           Voyage and scheduling factors
       oo Frequency of port calls
       oo Time between ports
       oo Routing
       oo Weather and sea condition on route
       oo Traffic density on route
       oo Nature of duties/workload while in port and at sea
    
 Module 2 provides recommended strategies for controlling and managing fatigue risks due to management factors. 
    
 C. Ship-specific Factors

 These factors include ship design features that can affect and contribute to  fatigue. Some ship design features affect workload (i.e. automation, equipment 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, not all inclusive, list details ship-specific factors:

       oo Ship design
       oo Level and complexity of automation
       oo Level of redundancy
       oo Equipment reliability
       oo Inspection and maintenance
       oo Age of vessel
       oo Physical comfort in work spaces

       oo 
       oo           Location of quarters
       oo Ship motion
       oo Physical comfort of accommodation spaces

 Module 5 provides recommended strategies for controlling and managing fatigue risks due to ship-specific factors. 
 
 
 D. Environmental Factors

 Exposure to environmental disturbances within areas in which seafarers live and work (both inside and outside the ship) can impact the onset of fatigue, and  sleep duration, quantity and quality.  Long-term exposure may even cause harm to a person's health. Environmental factors to consider include excessive noise and vibration, inadequate ventilation, excessive heat or cold, too much or too little humidity, poor air exchange, poor lighting and excessive ship motion. 

      Noise is an environmental stimulant that activates mental and physical reactions in the body and can disrupt sleep no matter how low and soft that level of sound pitch and intensity is. Noise, whether high/ loud (main engines, switchboards) or low/soft (radio in another cabin, TV in lounge, conversations, etc.), can affect the duration, quantity, and quality of sleep a person gets. Noise can also affect the ability to fall asleep, causing sleep loss, or it can alter one's sleep stage or depth of sleep. 

      Vibration affects sleep and fatigue. For example, vibration, similar to excessive noise may keep people awake, keep them from deeper sleep, or wake them up. The risk of being woken up is especially high when people are in the early stages of sleep, because they can be easily awakened. This can potentially lead to a situation in which an individual's sleep will never reach the important deep sleep stage. Moreover, when noise or vibration disrupts the early deep sleep stages, it has the same impact as loss of sleep, because people need to go through all stages of sleep before they can be fully restored.
 
      Lighting can also delay or advance the onset of sleep and hence impact fatigue levels. The body clock is highly influenced by light exposure and its intensity. The effect of light on the body clock is dependent upon when in the circadian cycle light exposure occurs. For example, light exposure prior to bedtime can interfere with sleep duration, quantity, and quality. The intensity of light also plays a major role. Bright light causes bigger shifts (delays and onset of sleep) in the body clock than dim light, and the clock is particularly sensitive to blue light (which promotes alertnessAlthough light is one of the most influencing factors in the body clock, in reality, staying in step with the day/night cycle is more complex than this. On ships, seafarers may have very haphazard exposure to light, depending on whether they are working during the day or during the night. This also depends on their exposure to natural light (whether working in the engine control room or on the bridge.
 
      In addition, the use of personal devices (such as laptops and smart phones) specifically ones that emit blue lighting can also influence the biological clock and can delay the onset of sleep, especially when used in the evening prior to bedtime. 
      
      Exposure to bright light also has immediate and significant effects on improving alertness and mood. Conversely, limited exposure to bright light can negatively impact mood, similar to the effects on mood due to seasonal changes in the light-dark cycle. As such the pattern of light dark exposure should be balanced to optimize the effects on circadian timing and the immediate effects on alertness and mood.
 
      Ship motions: Depending upon the weather and sea conditions, the vessel may be subject to ship motions which can interfere with sleep. From a fatigue perspective, ship motion is associated with motion-induced fatigue and seasickness. Motion induced fatigue is related to the extra energy expended to maintain balance while moving, especially during harsh sea conditions. There is a direct relation between a ship's motion and a person's ability to work. This also means that the combined effect of workload in a moving environment accelerates the onset of fatigue. Seasickness, another negative consequence associated with ship motion is caused by a conflict between the eyes, perceiving that the person is stationary, and the body, feeling motion. Seasickness causes symptoms such as feelings of nausea, vomiting, dizziness, visual problems (including impaired night vision), and memory problems. A person who is seasick  is more vulnerable to fatigue.
 
      Temperature and humidity: Generally, one experiences high ambient temperatures as dry heat (temperature above 24° C, humidity less than 50%) or as humid heat (temperature above 24° C, humidity above 80%).influence a seafarer's level of fatigue. All excessively hot and even 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 effects sleep and alertness. For example, the body sleeps best when the environmental temperature is between 18 and 24°C. 
 

 

 There are a number of things that can be done to address these causes. Some contributors are more manageable than others. Opportunities for implementing countermeasures vary from one factor to another (noise can be better addressed during the vessel design stage (see Module 5), breaks can be addressed by the individual crew member, training and selection of the crew can be addressed during the hiring process, etc.). 

 Modules 2 - 6 provide a closer examination of the specific causes of fatigue and how each relates to specific industry groups.
 

 1.  Important basic concepts in understanding fatigue

The most significant aspects of fatigue are:

 * The importance of adequate sleep (not just rest) for restoring and maintaining all aspects of waking functions; 
 * The influence of circadian rhythms and the body clock, on the ability to remain awake and alert to perform mental and physical work effectively and to acquire effective sleep (during day and night time);
 * The influence of increasing hours of wakefulness on the need and pressure for sleep; 
 * The influence of stress on fatigue; 
 * The influence of workload (physical and mental task related factors) on the speed of onset of fatigue; and 
 * The importance of a healthy lifestyle in better managing and preventing the risks of fatigue.

 This section highlights some of these important concepts that provide an overall understanding about fatigue.

 A.     Sleep

 Repair, restoration and maintenance of physical and mental functions are undertaken during sleep.  
 
 Sleep is an active process; when people sleep they are actually in an altered state of consciousness. All sleep does not have the same quality and does not provide the same recuperative benefits. In order to satisfy the needs of the human body, sleep must have three characteristics to be most effective:



  oo      Duration 
  oo      Quality
  oo      Continuity

    
    
    
    
    
    
    
 ADDIN EN.CITE  ADDIN EN.CITE.DATA 
    
    
    
    
*       Duration:  Everyone's sleep needs are unique; however, it is generally recommended that a person obtain, on average, 7 to 8 hours of sleep per 24-hour day.  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 over several consecutive days will impair alertness. Only sleep can maintain or restore performance levels. 
*             Continuity:  The sleep should be uninterrupted.  For example six one-hour naps do not have the same benefit as one continuous six-hour period of sleep. To note is that the proportion of time spent in deep sleep decreases as we get older, particularly amongst men.  Sleep also becomes more fragmented as we get older.
*       Quality:  People need deep sleep. Just being tired is not enough to ensure a good sleep. An individual must begin sleep in synch with the biological clock to ensure quality sleep. If the time of sleep is out of synchronization with his/her biological clock, it is difficult to sleep properly.

 Many factors contribute to sleep disruption and poor sleep quality, some are within our control while others are not:
       oo environmental factors (e.g. ship's movement, weather, heavy vibration, noise or poor accommodation)
       oo food and consumption of chemicals (e.g. alcohol intake, coffee, medication, etc.)
       oo psychological factors (e.g. stress, family worries, on-duty responsibilities)
       oo sleep disorders (e.g. insomnia - prolonged inability to obtain adequate sleep
       oo , sleep apnea - )
       oo operational factors (e.g. disruptions caused by drills, loading and unloading)
                                                                  oo           
    Transitioning from sleep to wake:
      Sleep inertia is a transitional state of lowered arousal occurring immediately after awakening from sleep and producing a temporary reduction in subsequent performance.
      
 B. Body Clock and the Circadian Rhythm

 Initially 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 wake, humans are biologically programmed to be active during the day and to sleep at night. However, maintaining set schedules and not rotating schedules will alleviate some of the effects associated with the circadian shift. 
 
 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 regulates the circadian rhythm. The body clock is perfectly synchronized to the traditional pattern of daytime wakefulness and night-time sleep.

 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 isn't the same for everyone.  Although individual rhythms vary, each person's cycle has two distinctive peaks and dips. Independent of other sleep-related factors that cause sleepiness, there are two times of low alertness (low-points or dips) in each 24-hour period . These commonly occur between 2-5am and 2-5pm for people on a normal daytime work schedule. Preceding these lowest alertness periods, are maximum alertness periods (peaks).
 
 
 
 
 
 
 
 
 


 oo 


 oo 

 
The states of sleep/wakefulness and circadian rhythms interact in several ways: 
-	The two can work against one another 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. 
-	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.

For many seafarers, working patterns conflict with their biological clock. Irregular schedules caused by shifting rotations, crossing time zones, etc. cause the circadian rhythms to be out of synchronization.

Further, the internal clock can only adjust by an hour or two each day. Sometimes, depending on the new schedule, it takes several days to adjust. In the meantime, the internal clock wakes a person up when they need to sleep and puts them to sleep when they need to be awake.
 
 
 Even though the body clock can be reset over time, such as when changing time zones for an extended period, research shows that it cannot be permanently adjusted to a reversed cycle of work and sleep even if external events remain the same, such as occurs on ships. The fact that the body clock does not adapt fully to altered sleep/wake patterns has two main consequences:

 oo duty times that overlap with seafarers' usual sleep times (particularly night operations) tend to cause sleep restriction and potentially a sleep debt; and
 oo seafarers who work through the night can be expected to be sleepy and have to make additional effort to maintain alertness and performance.

C. Time Awake

 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.

 Alertness and performance levels begin to decrease after a certain number of hours awake, with long duty periods (12 hours or more) associated with higher levels of fatigue than shorter duty periods (8 hours or less) due to extended wakefulness and demands on attention. The risk of an accident in the12th hour of work is "more than double" the risk of an accident in the 8th hour of work. In addition, the longer an individual has continuously been on a task without a break the more likely they will be fatigued. For every continuous hour worked beyond eight or nine (continuous) hours, the risk of an accident increases exponentially.

 Many seafarers work more than 12 hours per day and a working week of over 70 hours is common practice at sea. This makes them particularly susceptible to fatigue. Long work hours are associated with poor performance, higher injury rates, poorer safety, and/or health outcomes (both mental and physical).

 While the amount of wakefulness at sea prior to a dayshift may be typically short (between 30 minutes to 1 hour) during night-time work seafarers may have been awake for many consecutive hours prior to the start of a night duty, increasing the risk of fatigue. 

 Seafarers who work long hours will have reduced cognitive ability, less energy, and less ability to plan and prioritize. Thus, fatigue risk management should consider the effect of cumulative wakefulness, both prior to and throughout the duty period.

D.  Workload
 
 Workload is an important factor which leads to the onset of fatigue. Workload refers to the type and intensity of tasks performed. Fatigue can occur when workload is either very high or very low. High workload and monotonous tasks, which are both present in a shipboard work environment, are most likely to be fatigue inducing.
 
    High workload
 Both high physical and mental workload are a concern. Tasks with a very high mental workload result in fatigue due to excessive demands on attention. Fatigue resulting from workload becomes an increasing concern when combined with long periods of wakefulness and long duty hours. Examples of high workload routinely experienced on board ships include (but are not limited to), navigating in congested and dangerous waters, navigating in conditions of poor visibility, and/or bad weather, entering and exiting a port/harbour, having to complete multiple tasks, tank cleaning, cargo operations, etc. The number of port calls also leads to high workload and needs to be taken into account because more port calls involves more berthing/unberthing; loading/unloading, which are both task intensive and safety critical and can accelerate the onset of fatigue.
 
    Low workload
 In addition, tasks that have a very low mental workload, such as monitoring (e.g. engine room displays) 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 (e.g. night duty). People are generally not good at long duration vigilance tasks. Research indicates that performance consistently declines beyond two hours of conducting monitoring and vigilance tasks. Furthermore, it is difficult to maintain performance at a safe level after four to five hours of continuous vigilance. Performance and alertness is further impacted if vigilance and monitoring tasks need to be carried out during the night time hours, specifically between 0000 and 0500 hours. 

 E. Stress

 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/her inability 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 personal situation.

Stress can be caused by a number of factors, including:
    oo Environmental hardships (noise, vibration, exposure to high and low temperatures, etc.)
    oo Weather (i.e. ice conditions)
    oo Personal problems (family problems, home sickness, isolation, etc.)
    oo Inadequate restorative sleep 
    oo Broken rest
    oo Long working hours
    oo Intense mental and/or physical workload
    oo On-board interpersonal relationships
    oo Job control


 
 All these stressors can influence levels of fatigue by impacting on the extent to which a seafarer is able to acquire sufficient sleep. 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 from home for extended periods of time. This lifestyle imposes serious strain on seafarers and their families. Loneliness, isolation, family conflict, and concern about family members provide enough stress to be considered risk factors. Families provide a source of intimacy, support, continuity, satisfaction, and pride. Seafarers who leave their homes for extended periods of time miss out on these benefits.
 
 Furthermore, in some cases seafarers do not get the relief of being detached from work. This is particularly challenging on a ship where crew are constantly reminded about work while off-duty and off the ship and are expected to recover from their work environment.
 
 

E. Health

 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 on sleep and therefore contribute to fatigue.  
 

    Nutrition: 
    An unbalanced diet that does not include fresh fruits and vegetables can adversely affect a seafarer's health and contribute to fatigue.  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 five times more likely to get peptic ulcers than day workers are.
    
    
    Hydration: 
    Dehydration can lead to fatigue and lack of concentration. 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.
    
    
    Exercise and Fitness: 
    Poor physical fitness adversely affects overall health and causes people to tire easily. Exercise speeds up metabolism and increases blood flow, carrying oxygen to the brain. The increase in metabolism and blood flow 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 crewmember's ability to increase physical fitness, enhance sleep, think clearly, and manage stress. 
    
    
    Caffeine and other stimulants: Incorporate language from MEDMAC.... People who work during the night and even those who work long hours tend to drink a lot of caffeinated beverages to get through the work period. Caffeine occurs naturally in many plants including coffee beans, tea leaves, and cocoa nuts. It is also found in an array of food products and beverages such as chocolate and cola 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, blood pressure, and can cause fatigue in some people. It takes caffeine about 15  -  30 minutes to enter the body's system, and its physiological effects peak after about an hour after the drug reaches the bloodstream. The effects of caffeine can be highly variable from individual to individual and depends on physical condition, age, level of sleep debt, frequency of use, and time of day.  Generally, caffeine levels drop by half every 5-6 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, which is particularly bad when an individual, for example is experiencing seasickness.
    
    Alcohol: Alcohol is a central nervous system depressant. Alcohol can lead to increased sleepiness and reduced alertness, even after the alcohol is no longer detectable. This effect is commonly known as a hangover. Even in smaller doses alcohol can interfere with restorative sleep. There are also serious health consequences related to the long-term abuse of alcohol. These problems include alcoholism, cardiovascular disease, abnormalities in the absorption of food nutrients, chronic pancreatitis, liver disease, brain damage, and cancer. Sustained alcohol abuse is also associated with interpersonal, financial and employment problems.  Many shipping companies have `zero alcohol tolerance'. 
    
    Nicotine: Nicotine is highly addictive and the dangers to health are well documented. Smokers generally have more disturbed sleep, typically taking longer to fall asleep and experiencing more wake time during a sleep period. Smoking also increases the chances of heart and lung disease, gum disease, numerous cancers, poor circulation and dozens of other health problems. Smoking complicates a range of medical conditions, including asthma, tuberculosis and pneumonia. Most smokers are less fit than non-smokers are.
    
    Drugs and Supplements: 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. Additionally, 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. It is important for seafarers to be aware of how drugs and supplements may affect their health and their sleep-wake cycles.  They should proactively seek advice and guidance from their healthcare providers before using these products to learn about their appropriate use.
    
    
    Sleep Disorders: Other health related aspects are the wide variety of sleep disorders known to disrupt the quality of sleep and make it impossible to obtain restorative sleep, even when individuals spend enough time trying to sleep. 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. The most common sleep disorders are obstructive sleep apnoea, insomnia, narcolepsy, and restless legs syndrome. Large numbers of individuals suffering from sleep disorders are unaware of and have not been diagnosed or treated for their disorder. 
   oo    Obstructive sleep apnoea (OSA) is a disorder in which breathing is interrupted during sleep. . Repetitive episodes of non-effective breathing, very shallow breaths, or adequate breaths lead to frequent partial arousals from sleep, resulting in ineffective sleep and sleep debt.  Excessive daytime sleepiness is a major symptom of this condition. 
   oo  
   oo Insomnia is the most prevalent sleep disorder and is characterised by an inability to fall asleep and/or by waking up during the night and having difficulty going back to sleep. Primary insomnia is more common in women than men and tends to increase with age. Short-term or transient 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.  
   oo Restless legs syndrome (RLS) 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 the 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. 
   oo Shiftwork Sleep Disorder is a circadian rhythm sleep-wake disorder that is thought to affect up to 10% of shift workers. Symptoms include insomnia and/or excessive sleepiness associated with the shift work schedule. The condition is closely linked with the work schedule, and symptoms typically resolve when the major sleep period is at conventional times. Although symptoms may persist for a few days after the cessation of the work schedule if some alignment to the shift work schedule has occurred. In comparison to shift workers without shift work disorder those with shift work disorder complain more mood problems such as impatience and depression, as well as an more self-reported health complaints such as ulcers and substance use. Reference is the: ICSD-3. The International Classification of Sleep Disorders: Diagnostic and Coding Manual. 2nd ed. Darien, IL: American Academy of Sleep Medicine; 2014.
   oo 
   oo 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. Daytime sleep attacks may occur without warning and may be irresistible. In addition, night-time sleep may also be fragmented. Narcolepsy results in difficulty staying awake, and in extreme conditions, sleeping episodes can occur during periods of safety sensitive activity. 
      
F. Individual differences
      
 Individuals respond to fatigue differently and may become fatigued at different times, and to different degrees of severity, under the same circumstances. For example as people get older, they generally find it more difficult to sleep when they want to sleep and to stay asleep. This is particularly true during daytime sleep, but even night-time sleep may prove to be more challenging as people get older. This means that coping with night time work becomes increasingly more difficult with age. There are also individual characteristics related to circadian rhythms. People can be characterised as morning or evening types depending on the period of the day when they perform at their best. Morning people adapt better to early morning hours but will have difficulty coping with night work. Evening types cope more easily with evening and night shifts, and catch up by sleeping late in the morning. 

 1. Effects of fatigue



 When a person is affected by fatigue, his or her 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, judgment, hand-eye coordination, and countless other skills. When impairment due to fatigue, such as impaired memory or poor communication, coincides with other operational 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.

 Fatigue is dangerous in that people are poor judges of their level of fatigue. The following is a sample of fatigue's known effect on performance. 

       oo        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)
       oo        Chronically fatigued individuals will often select strategies that have a high degree of risk on the basis that they require less effort to execute


       oo        Fatigue can affect an individual's ability to respond to stimuli, perceive stimuli, interpret or understand stimuli, and it can take longer to react to them once they have been identified.
       oo        Fatigue also affects problem solving which is an integral part of handling new or novel tasks.

 A particular dangerous situation at sea emanating from sleep debt are brief uncontrolled and spontaneous sleep episodes whilst working, termed micro-sleeps. As highlighted, the pressure for sleep increases progressively across successive days of sleep restriction. This is particularly more so if the individual is on duty during the circadian low. During a micro-sleep, the brain disengages from the environment (it stops processing visual information and sounds). Research has shown that individuals working arduous duty schedules are particularity at risk of micro-sleeps. 
 
 The range of effects and signs of fatigue can typically be grouped into three categories: mental (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 1.1: Fatigue signs and symptoms
 
 
                                     Mental
 
 Symptom
 Signs
 Inability to concentrate
   oo    Unable to organize a series of activities
   oo    Preoccupied with a single task
   oo    Focuses on a trivial problem, neglecting more important ones
   oo    Reverts to old but ineffective habits
   oo    Less vigilant than usual
   oo    Decline in ability to solve complex problems
   oo    Lapses of attention
   oo    Difficulty multitasking
 Diminished decision-making ability
oo Misjudges distance, speed, time, etc.
oo Fails to appreciate the gravity of the situation
oo Overlooks items that should be included
oo Chooses risky options
oo Difficulty with simple arithmetic, geometry, etc.
oo Greater indecisiveness
 Poor memory
oo Fails to remember the sequence of task or task elements
oo Difficulty remembering events or procedures
oo Forgets to complete a task or part of a task
oo Memory lapses
 Slowing of mental processes
 Responds slowly (if at all) to normal, abnormal or emergency situations
 
                                    Physical
 
 Symptom
 Signs
 Involuntary need to sleep 
oo May appear to be drunk
oo Affected speech e.g. it may be slurred, slowed or garbled, hard to find the right words
oo Feeling heaviness in the arms and legs
oo Increased frequency of dropping objects like tools or parts
oo Tremor
oo Clumsiness 
oo Slow eyelid closures
oo Droopy eyelids
oo Itchy eye
oo Involuntary sleep attacks
oo Inability to stay awake
oo Micro sleeps
oo 
oo 
oo 
oo 
oo 
 Involuntary need to sleep Loss of control of bodily movements
oo Inability to stay awake
oo Micro sleeps
oo Involuntary sleep attacks
oo Slow eyelid closures
oo Droopy eyelids
oo Itchy eyeMay appear to be drunk
oo Affected speech e.g. it may be slurred, slowed or garbled, hard to find the right words
oo Feeling heaviness in the arms and legs
oo Increased frequency of dropping objects like tools or parts
oo Tremor
oo Clumsiness
 Health Issues
oo Headaches
oo Giddiness
oo Rapid breathing
oo Digestion problems
oo Leg pains or cramps
oo Insomnia
oo Sudden sweating fits
oo Heart palpitations / irregular heart beats
 
                                  Behavioural
 
 Symptom
 Signs
 Mood change
oo Quieter, less talkative than usual
oo Unusually irritable
oo Increased intolerance and anti-social behaviour
oo Depression
 Attitude change
               oo    Less desire to socialise
               oo    Fails to anticipate danger
               oo    Fails to observe and obey warning signs
               oo    Seems unaware of own poor performance
               oo    Too willing to take risks
               oo    Ignores normal checks and procedures
               oo    Displays a "don't care" attitude
               oo    Weakness in drive or dislike for work
               oo    Loss of appetite (and sometimes an increase in unhealthy eating habits)
               oo    Low motivation to perform optional activities
 
 Sleep debt, specifically irregular work hours 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 affects also point to mental health problems such as negative mood states and depression.
 
 In addition, a substantial body of literature has linked long working hours (defined as more than 60 hours per week) over several years, with poorer health and wellbeing such as lower mental health status, self-reported hypertension, heart problems, high blood pressure; gastrointestinal disorders; job dissatisfaction, smoking, and frequent circadian disruption including effects on eating and sleeping. 

 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 high instances of injuries and accidents (e.g. Fingal (2007); Antari (2008); Shen Neng 1 (2010); Spring Bok (2012)) reportedly related to fatigue within maritime operations suggest that the impact of fatigue results in great economic, environmental and human cost. Hence, unless steps are taken to alleviate fatigue, it will remain long after the period of sustained attention, posing a hazard to ship safety. 
 Thus, fatigue management systems which address the risks of fatigue and its causes are essential.
 
 
 
 
 1. Rules and regulations dealing with fatigue

Rules and regulations directly dealing with fatigue are mainly set out in the following instruments:

* IMO, Standards of Training, Certification and Watchkeeping for Seafarers (STCW) Convention, 1978, as amended; and
* ILO, Maritime Labour Convention, 2006.

These will be discussed in more detail in Modules 2, 3 and the Appendix. 






                                                 References

 Calhoun S.R. (1999)  -  Human Factors and Ship Design: Preventing and Reducing Shipboard Operator Fatigue. University of Michigan/U.S. Coast Guard Research Project  -  Michigan, United States.

 Kroemer K.H.E., Grandjean E. (1999)  -  Fitting the task to the Human (Fifth Edition). Taylor and Francis, Ltd.  -  United Kingdom.

 Sandquist T., Raby M., Maloney A.L., Carvalhais T. (1996) - Fatigue and Alertness in Merchant Marine Personnel: A field study of work and sleep patterns. Report No. CG-D-06-97. Batelle Seattle Research Center and U.S. Coast Guard Research and Development Center  -  Connecticut, United States.

 Transportation Safety Board of Canada (1997) - A Guide for Investigating for Fatigue  -  Canada


