How we change what others think, feel, believe and do

Fatigue

Explanations > Theories > Fatigue

Description | Research | Example | So What? | See also | References 

Description

Causes of fatigue include:

• Insufficient, interrupted or irregular sleep
• Disruption of the biological clock and daily patterns of activity
• Incorrect nutrition, especially deficiencies of B vitamins, vitamin C, magnesium, sodium, zinc, L-tryptophan, L-carnitine, coenzyme Q10, and essential
  fatty acids.
• Insufficient water intake.
• Various drugs, especially those that affect muscles.
• Conditions such as Chronic Fatigue Syndrome.
• Age
• Physical activity
• Stress
• Cognitive effort
• Boredom
• High levels of noise

Symptoms of fatigue include:

• Forgetfulness
• Reduced ability to communicate clearly
• Yawning
• Always tired
• Closing eyes, nodding off
• Lack of alertness
• Drowsiness
• Socially withdrawn
• Moodiness, quick to anger
• Sore eyes
• Depression
• Lack of self-regulation
• Impaired decision skills

Physical fatigue reduces the ability to perform physical activities such as running and lifting. Fatigue also affects cognitive functioning and it becomes harder to think and make effective decisions. This is significant wherever choice is important, such as for doctors and nurses, soldiers, etc.

We like choice as it gives us a sense of control. Yet increased choice requires more cognitive effort, which is more tiring, causing decision fatigue. This can lead to people preferring less choice, which can seem counterintuitive (Iyengar and Lepper, 2000).

Research

Fletcher et al. (2003) and others have found similar patterns of performance loss when comparing the effects of fatigue and alcohol.

Example

A tired nurse forgets to administer critical drugs to a patient.

Near the end of an energetic match, a footballer passes the ball to an opposing player when a team-mate was nearby and could easily have taken the ball.

So What?

Using it

People may well be easier to persuade when they are tired, both because they do not have the energy to argue and because they will put less effort into deciding.

When giving people a choice, you can give them less to make it easier, or give them a lot if you want to tire them so you may then make a recommendation that is easier to accept.

Defending

Avoid important decisions when you are tired. Sleeping on decisions is a good way to make better decisions.

See also

Stress, Ego Depletion

References

Fletcher, A., Lamond N., Van Den Heuvel CJ, Dawson D. (2003). Prediction of Performance during Sleep Deprivation and Alcohol Intoxication using a Quantitative Model of Work-Related Fatigue. Sleep Research Online, 5(2), pp. 67-75

Iyengar, S. S., & Lepper, M. R. (2000). When choice is demotivating: Can one desire too much of a good thing? Journal of Personality and Social Psychology, 79, 996-1006

Kim. S., Cranor. B.D. and Ryu, Y.S. (2009). Fatigue: Working Under The Influence, Proceedings of the XXIst Annual International Occupational Ergonomics and Safety Conference, 317-322