Toolbox Talk

Toolbox Talk: “Fatigue and Its Effects”

Fatigue is mental or physical exhaustion that stops a person from being able to function normally. However, fatigue is more than just feeling tired or drowsy – it is normal to become tired through physical or mental effort.

Work performance

High levels of fatigue cause reduced performance and productivity, and increases the risk of accidents and injuries.

Fatigue affects the ability to think clearly. As a result people who are fatigued are unable to gauge their own level of impairment, and are unaware that they are not functioning as well or as safely as they would be if they were not fatigued.

Performance levels drop as work periods become longer and sleep loss increases.

Staying awake for 17 hours has the same effect on performance as having a blood alcohol content of 0.05%.

Staying awake for 21 hours is equivalent to a blood alcohol content of 0.1%.

The most common effects associated with fatigue are:

• desire to sleep

• lack of concentration

• impaired recollection of timing and events

• irritability

• poor judgment

• reduced capacity for communicating with others

• reduced hand-eye coordination

• reduced visual perception

• reduced vigilance

• reduced capacity to judge risk

• slower reaction times.

Not only do these effects decrease performance and productivity within the workplace, but they simultaneously increase the potential for incidents and injuries to occur.

People working in a fatigued state may place themselves and others at risk, most particularly:

• when operating machinery (including driving vehicles)

• when performing critical tasks that require a high level of concentration

• where the consequence of error is serious.

Micro sleeps

A micro sleep is a brief nap that lasts for approximately four to five seconds.

People who suffer from micro sleeps are not always aware when a micro-sleep occurs, which can have a significant effect on safety.

Health effects

The effects of fatigue increase with age.

People over 50 years of age tend to have lighter, fragmented sleep; which can prevent them from receiving the recuperative effects from a full night of sleep, and can make them more likely to become fatigued.

Lack of sleep has been indirectly linked with health effects such as:

• heart disease and high blood pressure.

• stomach disorders.

• mental illnesses.

• lower fertility.

When the circadian rhythm is disrupted, the treatment of some medical conditions can be affected.

Examples of medical conditions which may be affected include:

• asthma

• depression

• diabetes.

Heart disease and high blood pressure

Circadian disruptions affect eating and sleeping habits and have been linked to the following types of cardiovascular disease:

• coronary heart disease (blocked arteries in the heart)

• Ischaemic heart disease (blocked arteries leading to lack of oxygen to the heart muscle)

• high blood pressure

• Myocardial infarction (heart attack).

Stomach disorders The body rhythm for digestion is designed for food to be eaten during the day irrespective of whether an individual is working or resting.

The most common complaints include:

• bowel habit changes

• digestive complaints

• increased risk of peptic (stomach) ulcers.

Mental health Anxiety and depression can be triggered or made worse by fatigue and irregular sleep patterns.

Lower fertility

Fatigue and irregular sleep patterns have been associated with a number of negative effects for pregnant women and fertility rates, including:

• increased risk of miscarriage

• low birth weight

• higher occurrence of premature births.

Ref: http://www.deir.qld.gov.au/workplace/hazards/fatigue/effects/index.htm

“A man without decision of character can never be said to belong to himself . . . . He belongs to whatever can make captive of him.”— John Foster