Focus on Fatigue

Caffeine can only do so much

By August 25, 2021 No Comments

Issue #70 – July 2021

Welcome to Focus on Fatigue!

Do you rely on coffee, or another form of caffeine, to get you up and going in the morning, to counteract the mid afternoon slump or to get you through the night shift? If so, you are not alone! Caffeine is consumed by over 80% of U.S. adults.

Caffeine is a stimulant, widely known to help you stay awake and stave off tiredness. However, in this month’s Focus on Fatigue, we will look at how effective caffeine is in counteracting the affects of sleep deprivation and whether it has it’s limits.

The FRMS Team



InterDynamics Pty Ltd
320 Adelaide Street Brisbane Qld 4000
Tel +61 7 3229 8300

Views expressed in articles and links provided are those of the individual authors, and do not necessarily represent the views of InterDynamics (except where directly attributed).

Caffeine can only do so much….

A recent study from MSU’s Sleep and Learning Lab has assessed how effective caffeine is in counteracting the negative effects of sleep deprivation on cognition. The study found that while caffeine counteracted impairment caused by sleep deprivation on a simple attention task (PVT), it did not significantly affect performance in a more challenging placekeeping task (UNRAVEL).

Placekeeping ability is a cognitive control process that plays a role in procedural performance, problem solving and other higher order tasks. It is the ability to perform the steps of a complex task in a prescribed order without skipping or repeating steps.

The study concluded that this finding “has implications for intervention research and suggests that caffeine has limited potential to reduce procedural error rates in occupational settings”.

While there are short term benefits to consuming caffeine during periods of sleep loss, it is worth being aware of caffeine’s limitations. Let’s break down what we know.

Caffeine can:

  • Increase alertness and reduce fatigue
  • Improve mood
  • Help maintain cognitive performance – Caffeine can help counteract degraded cognitive task performance due to sleep deprivation on vigilance tasks and simple tasks that require sustained focus and response.
  • Help maintain physical performance

However, caffeine can also…

  • Make you overconfident – Caffeinated people are more likely to feel confident about their work performance, even when that performance has suffered. This may have serious consequences in real-life situations where accurate self-perception is crucial for avoiding risks.

Caffeine does not:

  • Help with complex decisions – Caffeine does not help you make complex decisions in the face of changing information. While the effects of caffeine consumption on complex decision making have not been well researched, one study did find that a moderate dose of caffeine did nothing to reverse the effects of sleep deprivation in this sort of context. In other words, drinking coffee may make you feel alert, but it may not help you think more clearly in complex situations.
  • Improve performance in complex tasks – Caffeine does not appear to significantly counteract performance impairment, caused by sleep deprivation, in procedural performance, problem solving and other higher order tasks.
  • Replace sleep – Sleep gives your brain time to conduct a whole host of basic maintenance jobs that it simply cannot do when you’re awake.

While caffeine can be a useful tool, it does have it’s limitations and there is no real substitute for sleep!


  • Kamimori, G.H., McLellan, T.M., Tate, C.M. et al. (2015) Caffeine improves reaction time, vigilance and logical reasoning during extended periods with restricted opportunities for sleep. Psychopharmacology 2322031–2042.
  • Ker, K., Edwards, P. J., Felix, L. M., Blackhall, K., and Roberts, I. (2010). Caffeine for the prevention of injuries and errors in shift workers. Cochrane Database of Systematic Reviews, 5, CD008508.
  • Killgore, W. D. S., Lipizzi, E. L., Kamimori, G. H. and Balkin, T. J. (2007) Caffeine effects on risky decision making after 75 hours of sleep deprivation. Aviation, Space and Environmental Medicine, 78, 957-962.
  • McLellan, T., Caldwell, J. & Lieberman, H. (2016), A review of caffeine’s effects on cognitive, physical and occupational performance. Neurosicence & Biobehavioral Reviews, 71, 294-312.
  • Smith, A. (2002) Effects of caffeine on human behaviour. Food and Chemical Toxicology, 40(9), 1243-1255. http://doi.org10.1016/s0278-6915(02)00096-0
  • Smith, P. F., Smith, A., Miners, J., McNeil, J. and Proudfoot, A. (2000) The safety aspects of dietary caffeine. Expert Working Group on Caffeine. Australia New Zealand Food Authority. Canberra, Australia.
  • Stepan, M. E., Altmann, E. M., & Fenn, K. M. (2021). Caffeine selectively mitigates cognitive deficits caused by sleep deprivation. Journal of Experimental Psychology: Learning, Memory, and Cognition. Advance online publication.

In the News

Provided below are a selection of articles from around the web on the issues associated with fatigue. We hope you find them useful and interesting.

Don’t count on caffeine to fight sleep deprivation

Michigan State University, Science Daily, May 2021
Sleep scientists assessed how effective caffeine was in counteracting the negative effects of sleep deprivation on cognition.

How overwork is literally killing us

Christine Ro, BBC, May 2021
Alarming new research shows that people working more than 54 hours a week are at major risk of dying from overwork. It’s killing three-quarters of a million people each year.

How caffeine and alcohol affect your sleep

Matt Walker, Sleeping with Science, July 2020
Caffeine wakes you up, and alcohol makes you nod off, right? It’s not that simple. Sleep scientist Matt Walker takes us into the eye-opening ways that these drinks affect the quantity and quality of our sleep

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