Recognizing and preventing fatigue at work…

before something happens!

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Scientific interpretation

Fatigue at work affects a large number of employees around the world. It is the third most-reported health problem in Europe [1], and more than one in five workers in the US say they feel tired at work. Yet, in addition to affecting people’s quality of life and weakening their immune system, fatigue at work also entails major costs. In the US alone, the cost of loss of productivity and health-care related to fatigue at work is estimated at $136.4 billion per year![2]

While all employees are likely to feel tired at some point, the issue of fatigue at work may not come up until after a major accident. Considering its profound impact on employees and on organizations, is it possible to identify and prevent fatigue at work before a serious incident happens?

With this in mind, we were interested in the study of Techera and colleagues, published in 2016, which aims to better understand the phenomenon of fatigue at work, examine its effects on workers’ health and highlight its leading causes.

Expert adviser

Philippe ZAWIEJA, Ph. D., research associate, Équipe sur les organisations en santé (ÉOS)


PATRICE DANEAU, research assistant, Université de Sherbrooke

Étienne FOUQUET, research assistant, Université de Sherbrooke

JOSÉE CHARBONNEAU, research assistant, Université de Sherbrooke

This initiative was made possible through a collaboration with the Université de Sherbrooke.


Fatigue at work

In this study, fatigue at work refers to a feeling of weariness or exhaustion of mental or physical strength felt by an employee who is subject to major demands or stress factors. It therefore leads to a reduced ability to carry out work activities at the desired level. Fatigue can be physical or mental.

It is a matter of physical fatigue when there is a reduction in the physical ability needed to exert strength or do a task.

Mental fatigue, meanwhile, is related to a decrease in motivation to do an activity or in the ability to deal with information and react to it.

When it is difficult, or even impossible, to separate physical fatigue from mental fatigue, the term general fatigue is used.

Fatigue at work can also be categorized based on how long the effects last. It is then a question of acute fatigue or chronic fatigue.

Note from our expert

The term “fatigue at work” is preferable to “occupational fatigue” due to the causes of fatigue, which can be caused not only by the job, but by factors outside work. In the end, it’s about managing the employee’s fatigue in the workplace.

Acute fatigue

Acute fatigue is a normal response to adverse conditions (e.g. mental or physical effort, emotional stress, insufficient recovery, temporary illness) that affects healthy people and has short-term effects. It can be relieved by rest, quality sleep, an appropriate diet, and exercise. In most workplaces, acute fatigue is the main concern when it comes to fatigue; that is the form discussed here.

Chronic fatigue

The symptoms of chronic fatigue are similar to those of acute fatigue, but are ongoing and last longer. Although it is still difficult to understand the causes, chronic fatigue can occur if acute fatigue is not relieved and at times follows a serious illness (e.g. rheumatoid arthritis, diabetes) or medical treatments (e.g. chemotherapy). Unlike acute fatigue, chronic fatigue cannot be relieved by rest.

Complete reference

Techera, U., Hallowell, M., Stambaugh, N., & Littlejohn, R. (2016). Causes and consequences of occupational fatigue: Meta-analysis and systems model. Journal of occupational and environmental medicine, 58(10), 961-973.




A method that allows researchers to bring together a certain number of quantitative studies to quantify the overall result and produce a single measurement estimate.[3]

  • Criteria for study inclusion:
    • Establish a clear relationship between a cause and fatigue or between fatigue and its result;
    • Involve a sample of workers who are in good health, are between 18 and 65 years of age, and represent the active population;
    • Include the measurement of a causal relationship (effect size) or enough information to calculate one;
    • Involve at least 5 participants in the sample.
  • Targeted journals: workplace health and safety, applied and cognitive psychology, medicine, engineering, neurosciences.
  • Results: Among the 105 studies that report empirical data, 23 respect the four inclusion criteria; among these, the researchers discovered 9 causes and 5 consequences of fatigue at work.


Analysis based on a systematic approach

The 9 causes and 5 consequences of fatigue at work are presented based on a systematic model: that is, they affect each other and cannot be considered in isolation.


The authors highlight five effects of fatigue at work. Although fatigue at work can be characterized more specifically based on its symptoms (physical or mental), the latter are often considered from a general perspective that encompasses both physical and mental fatigue.

5 main effects of fatigue at work

Mood disturbances

  • In general, fatigue at work can cause mood disturbances in the short term. Primarily associated with short-term emotions and feelings, mood is revealed in particular by psychological stress, anger, power, sadness or anxiety. In some cases, fatigue at work can lead to depression.


  • Long periods of fatigue at work can have a major impact on the worker’s health, weakening their immune system and contributing to the development of diseases (e.g. infections, gastro-intestinal problems, cardiovascular disease).
  • Workers who have a pre-existing health problem are more likely to experience fatigue at work.

Human errors and injuries

  • Errors and injuries happen when an action is not done correctly and/or causes loss or damage for the worker or others.
  • A worker who is physically or mentally fatigued can unwittingly put their health and safety, and even that of other people, at risk.

Decline of cognitive functions

  • Fatigue at work, especially mental fatigue, can weaken the worker’s basic cognitive faculties, such as their ability to concentrate and pay attention or their vigilance, and their complex cognitive faculties (e.g. planning, risk perception, decision making amid uncertainty). 
  • The decline of the worker’s cognitive performance also leads to a greater risk of errors.

Decline in physical condition and pain

  • Fatigue at work, especially physical fatigue, affects a worker’s physical abilities to do a task and can result in pain (e.g. musculo-skeletal problems).
  • Physical decline refers to any physical symptom that affects the body’s normal functioning, such as drowsiness, lack of strength, or pain.


A decline in cognitive function and physical condition as well as illness has effects that tend to exacerbate fatigue. For example, fatigue can cause illnesses that, in turn, can aggravate the symptoms of fatigue.

Caveat from the expert.

While the article focuses especially on the acute fatigue that occurs in a work context, the authors do not address burnout, which the work of Christina Maslach [4][5], defines as a syndrome with three dimensions, involving emotional and physical exhaustion, the appearance of a reactive “cynicism,” and the weakening (even the disappearance) of a sense of personal and professional accomplishment.

Burnout appears as a particular form of chronic general fatigue affecting a person’s physical and mental state that is not relieved by rest, whose main cause, as perceived by the worker, is the work environment.

Preventing fatigue at work

While the effects of fatigue at work can be harmful for the employee and the organization, they can nevertheless be avoided when we understand the causes of this phenomenon. The authors of the study highlight nine main causes that contribute to fatigue at work. These causes, which can arise from contexts both at work and outside of work, are presented in the following table, and actions are suggested.

The 9 main causes of fatigue at work




Causes related to the work context

High workloads

  • High cognitive and physical demands interfere with the recovery process.
  • When they are sustained or constant, high workloads contribute to fatigue at work.
  • Alternate more demanding work periods with less intense work periods.
  • Offer technical aids for physically demanding work.
  • Review the division of workload within the team and reorganize it as needed, to avoid inequalities and to maintain synergy.
  • Ensure that break times are respected and are good quality (free of demands) to permit recovery and then encourage the worker’s productivity.

Overtime and long working hours

  • A number of hours worked that exceeds 40 hours per week (overtime) or more than 8 hours per day (long working hours) can lead to fatigue at work.
  • The effects of overtime on worker fatigue depend on factors such as the voluntary aspect of overtime, the conditions in which it happens, the worker’s perception of benefits incurred, and personal motivations.
  • The type of fatigue in question depends on the physical or mental nature of the work.
  • Encourage volunteering to work extra hours, watching for the reasons for it (e.g. financial pressure, desire to please) and ensuring a fair rotation of employees involved.
  • Offer the possibility of teleworking.
  • Take into account the time needed for commuting during work-related travel.
  • Promote suitable commuting practices between home and work (e.g. carpooling, public transit, flexible schedule to avoid rush hour).

Unsuitable physical environment

  • Prolonged exposure to conditions such as noise, light intensity, vibrations or unsuitable temperature can lead to fatigue, whether through overstimulation or understimulation.
  • Vary work arrangements (open and closed spaces) to avoid both overstimulation (e.g. too much noise) and understimulation (e.g. too quiet, insufficient lighting).
  • Soundproof noisy or vibrating equipment.
  • Be sure to provide lighting that suits the task, and use natural light when possible.
  • Promote rules for proper conduct in shared spaces (telephone use, conversations).

Stressful social environment

  • The quality of interpersonal relationships at work as well as the perceived freedom play a major role in fatigue. For example, an environment characterized by harassment, poor perception of autonomy, high emotional demands or job insecurity can exacerbate mental fatigue.
  • Make employees and managers aware of various forms of harassment and discrimination.
  • Promote ethnic, cultural, religious and generational diversity and different ideas as a factor in creativity and innovation.
  • Beyond checking regularly on the state of employees and their work, take action to avoid problems, or manage them. If needed, ask for support from human resources.

Sustained or prolonged mental and/or muscular effort

  • A cognitively demanding task that lasts for more than 3.5 hours weakens the effectiveness of cognitive functions; mental awareness is only maintained with greater mental effort.
  • Employees faced with urgent situations, repetitive tasks and problem solving in their jobs (e.g. air traffic controllers) are more vulnerable to mental fatigue, as a larger number of cognitive functions are being called on at the same time.
  • Physical fatigue often occurs during a prolonged activity (e.g. working at high intensity, long working hours, poor posture). Dynamic muscular effort (impulsion) or static exertion (sustained contraction) can cause physical fatigue.
  • Prioritize and vary cognitively and physically demanding tasks.
  • Give quality breaks that are long enough and frequent enough, and promote them.
  • Protect quality time for thinking (watch out for multitasking).
  • Vary and share physical tasks among workers.
  • Promote healthy habits (e.g. hydration, exercise).

Insufficient recovery

  • Sufficient recovery allows workers to reverse the effects of a high workload or ongoing efforts.
  • On the other hand, insufficient recovery during shifts leads to general fatigue.
  • Give employees quality breaks that are long enough and frequent enough, depending on the nature of the task, and promote these.
  • Don’t think of the commute as a time of relaxation for the employee: traffic and road construction can be a stress factor.
  • Offer the possibility of taking short naps and/or relaxing.
  • Set up break rooms that encourage napping or quality breaks.

Causes related to the context outside of work

Sleep deprivation

  • Although there are different degrees of severity when it comes to sleep deprivation, less than 8 hours of sleep per night can reduce performance not only the next day, but also in the days that follow. More than 8 hours of sleep, however, is not more beneficial for the worker’s performance.
  • Ensure that employees can take advantage of the time needed to get at least 8 hours of sleep between their shifts.
  • As much as possible, adjust work hours or the sequencing of tasks to workers’ internal rhythm (some people feel more effective in the morning, and others, in the evening).
  • Close the work premises at a certain time in the evening, if possible.
  • Adopt a work–family balance policy, or allow, if possible, a flexible work schedule to avoid presenteeism.

Insufficient recovery

  • Break times and recreational activities are not enough to help a worker recover if they continue to have high physical or cognitive demands outside work or if they have poor lifestyle habits (e.g. alcohol abuse or drug use).
  • Recommend that workers use support services so they can get the support they need, as desired, to improve their lifestyle habits, while reducing their potential dependencies (e.g. drugs, leisure activities that can cause exhaustion, such as video games).
  • Maintain employees’ times of respite (e.g. holidays, time outside work hours). Alternatively, clarify that they are not expected to respond immediately outside of work hours.
  • Adopt a policy promoting disconnection outside of work hours.
  • Ensure that employees take their annual vacation.

Emotional predisposition

  • Fatigue affects workers differently based on their emotional predisposition: their level of fear, stress or overall attitude towards the task or the job.
  • Distress and stressful conditions exacerbate the effects of fatigue on people who are emotionally vulnerable.
  • Promote tolerance and mutual respect, and encourage the expression of individual differences so that each person can speak about their experiences at work.
  • Develop programs promoting recognition, as a positive approach, and reduce negative emotions.

Recommendations from our expert

WARNING! Overtime and long working hours increase the effects of fatigue caused by other factors, such as sleep deprivation, sustained mental or physical effort and insufficient recovery. In a similar way, a high workload can affect sleep deprivation, mental and physical effort, and even be at the root of overtime and long working hours. Fatigue at work is therefore rarely the result of a single cause.

Caveat from our expert

  • Like overwork, not enough work and understimulation can also lead to fatigue (e.g. boredom, bore-out).
  • Although not addressed in depth by the study, the subjective aspect of fatigue should not be overlooked. Indeed, factors that could explain fatigue at work can affect employees differently depending on their personal characteristics (e.g. personality; history; gender; group, ethnic or cultural belonging) and the context in which they evolve.
  • Fatigue prevention involves a holistic vision of the person and cannot be limited to work-related fatigue. Some fatigue whose cause lies outside of work can be alleviated through interventions by the employer: easier or preferential access to certain services (e.g. childcare, care for aging or sick relatives, carpooling). Paradoxically, reintroducing a certain division between the work environment and life outside work allows employees to have periods of relative calm: during work hours, work concerns; outside of work hours, personal concerns— and not both all day long!



Zawieja, J., Daneau, P., Fouquet, E., Charbonneau, J. (2018). Recognizing and preventing fatigue at work… before something happens!. Global-Watch Scientific Interpretation available at


Techera, U., Hallowell, M., Stambaugh, N., & Littlejohn, R. (2016). Causes and consequences of occupational fatigue: Meta-analysis and systems model. Journal of occupational and environmental medicine, 58(10), 961–973.


[1]Eurofound (2017). Sixth European Working Conditions Survey – Overview report (updated in 2017), Publications Office of the European Union, Luxembourg. Retrieved from the Eurofound website:

[2]Ricci, J. A., Chee, E., Lorandeau, A. L., and Berger, J. (2007). Fatigue in the U.S. workforce: Prevalence and implications for lost productive work time. Journal of Occupational and Environmental Medicine, 49(1), 1–10.
[3]Robson, C. and McCartan, K. (2016). Real World Research (4th ed.), United Kingdom: John Wiley & Sons.
[4]Maslach, C. and Leiter, M.P. (1997). The Truth About Burnout: How Organizations Cause Personal Stress and What to Do About It. San Francisco: John Wiley & Sons.
[5]Maslach, C. (2003). Burnout: The Cost of Caring. Cambridge, MA: Malor Books.

Pierre Breton
Author: Pierre Breton