What is fatigue?

Fatigue is the state of feeling very tired, weary or sleepy resulting from insufficient sleep, prolonged mental or physical work, or extended periods of stress or anxiety. Boring or repetitive tasks can intensify feelings of fatigue. Fatigue can be described as either acute or chronic.

Acute fatigue results from short-term sleep loss or from short periods of heavy physical or mental work. The effects of acute fatigue are of short duration and usually can be reversed by sleep and relaxation.

Chronic fatigue syndrome is the constant, severe state of tiredness that is not relieved by rest. The symptoms of chronic fatigue syndrome are similar to the flu, last longer than six months and interfere with certain activities. The exact cause of this syndrome is still unknown.

Is fatigue a workplace issue?

Fatigue levels are not easily measured or quantified; therefore, it is difficult to isolate the effect of fatigue on accident and injury rates.

Some research studies have shown that when workers have slept for less than 5 hours before work or when workers have been awake for more than 16 hours, their chance of making mistakes at work due to fatigue are significantly increased.

Research has shown that the number of hours awake can be similar to blood alcohol levels. WorkSafeBC reports the following:

• 17 hours awake is equivalent to a blood alcohol content of 0.05
• 21 hours awake is equivalent to a blood alcohol content of 0.08 (legal limit in Canada)
• 24-25 hours awake is equivalent to a blood alcohol content of .10

Fatigue is regarded as having an impact on work performance. Alberta Human Resources and Employment* reports that most accidents occur when people are more likely to want sleep – between midnight and 6 am, and between 1-3 pm. And, indeed, sleep deficit has been linked to large scale events such as the Exxon Valdez oil spill and the nuclear accident at Chernobyl.

*From: Alberta Human Resources and Employment. Fatigue, Extended Work Hours, and Safety in the Workplace in Workplace Health and Safety, June 2004, Reformated August 2010

How can a workplace help keep workers “alert”?

Fatigue is increased by:

• dim lighting,
• limited visual acuity (i.e., due to weather),
• high temperatures,
• high noise,
• high comfort,
• tasks which must be sustained for long periods of time, and
• work tasks which are long, repetitive, paced, difficult, boring and monotonous.

Workplaces can help by providing environments which have good lighting, comfortable temperatures, and reasonable noise levels. Work tasks should provide a variety of interest and tasks should change throughout the shift.

If extended hours/overtime are common, remember to consider the time required to commute home, meal preparation, eating, socializing with family, etc. Workplaces may wish to consider providing:

• on-site accommodations,
• prepared meals for workers, and
• facilities where employees can take a nap before they drive home.

Find this article & more information at www.ccohs.ca

Lisa Rowney / WCB Specialist / PEO Canada