05.06.2012

Worker 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.

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:


  • 17 hours awake is equivalent to a blood alcohol content of 0.5

  • 21 hours awake is equivalent to a blood alcohol content of 0.8

  • 24-25 hours awake is equivalent to a blood alcohol content of .10


A short podcast (4:24 minutes) explains how fatigue affects worker safety and
offers tips on minimizing the effects of fatigue.

Further Information


AplusA-online.de - Source: Canadian Centre for Occupational Health and Safety