Fatigue is an experience of physical or mental weariness that results in reduced alertness. Two major causes of fatigue are sleep loss and circadian rhythms.

How are circadian rhythms regulated?

Circadian rhythms are regulated by the body’s internal master clock which is located in the brain. This master clock controls many biological functions over a 24 hour period, such as the release of hormones, body temperature changes, and sleep-wake cycles.

What is the relation between night shift work and sleep loss?

Night shift work requires employees to be awake when the natural tendency is to be asleep, which disrupts body rhythms and affects the quality and quantity of sleep. Sleep loss is a additive and results in cumulative sleep debt.

What are the effects of fatigue for individuals and for organisations?

On the job, fatigue can be a serious safety hazard. Effects of fatigue reported by different studies are:


  • reduced attention and vigilance,
  • reduced reaction time – both in speed and thought,
  • reduced decision making ability,
  • reduced communication skills,
  • reduced productivity / performance,
  • reduced ability to handle stress on the job,
  • loss of memory or the ability to recall details,
  • failure to respond to changes in surroundings or information provided,
  • unable to stay awake ,
  • increased tendency for risk-taking,
  • increased forgetfulness,
  • increased errors in judgement,


  • increased safety risk,
  • increased absenteeism,
  • increased staff turnover,
  • decreased productivity,
  • increased medical costs, and
  • decreased employee satisfaction.

How can Fatigue be managed?

Fatigue can be managed effectively by implementing a Fatigue Risk Management System.

Defined by the International Civil Aviation Organization (ICAO) as:

A data-driven means of continuously monitoring and managing fatigue-related safety risks,

based upon scientific principles and knowledge as well as operational experience that aims

to ensure relevant personnel are performing at adequate levels of alertness.

Fatigue Risk Management required by European legislation:

The need for a Fatigue Risk Management System is increasingly recognized within Europe and is already partially included in the Aviation Industry as a mandatory element in European legislation (Commission Regulation (EU) No 83/2014)

Are you interested in the opportunities for your organisation?

Please contact: Info@qualiteit.nl