I have heard it all when it comes to tricks to fighting fatigue.  Everything from closing your pony tail in the car window glass so that it yanks your neck when your head falls forward from sleep (thanks Susan for this one), to eating sour apples or blasting the radio. While these tricks may make you feel less fatigued, they may not keep you safe because they do not bring your performance back up to a safe level.

I use the term “fatigue countermeasure” to describe the strategies you can use to fight fatigue that you may already feel or that you think you may be experiencing even if you don’t feel all that fatigued. A good countermeasure will return your performance to a safe level.

Here is a list of what works and what does not work as a fatigue countermeasure according to the science.

Splashing cold water on your face:

This trick may make you feel less fatigued for a few minutes but there is no scientific evidence to support it as a reliable fatigue countermeasure.

Eating a snack or eating snacks that take more “work” to eat like sunflower seeds, sour apples, peanuts or popcorn:

There is no strong scientific support for simply eating any old snack to wake you up.  In fact, eating can cause postprandial sedation.  This is the feeling of sleepiness that can occur after snacking.  There is some evidence to suggest that the increased brain glucose levels that occur when eating can stimulate the release of adenosine, a brain chemical that signals sleep[1].  If however, the snack contains enough caffeine, it can make you feel less fatigued and more importantly, it reliably improves your performance[2].

You might think that eating snacks that take more work to eat like peanuts or popcorn, or ones that seem to engage more of your senses like sour apples or sunflower seeds, would be good fatigue countermeasures. But the science on fatigue fighters does not back up this belief.  While these tricks may make you feel less fatigued, they might actually be risky ones to try.  When you are fatigued, even just a little bit, your brain’s ability to pay attention is already compromised[3]. This means it is much harder to pay attention to more than one task.  If you are trying to focus on eating sunflower seeds, it can make it harder for your brain to pay attention to more important tasks like driving.

Blasting the radio, turning down the temperature or opening the window:

A couple of studies have looked at whether exposure to cold air or listening to the radio could be used as effective and reliable fatigue countermeasures.  Listening to the radio seems to be a bit better than cold air exposure at reducing how fatigued you feel, but neither one keeps you safe from the effects of fatigue[4]. This means that blasting the radio, turning the air conditioning as cold as possible or opening the window on a cold day won’t bring your performance back up to a safe level.

Chew gum:

This one is pretty straight forward. Chewing gum makes you feel less fatigued[5] but there are no verified improvements in performance associated with this strategy[6]. 

Turning on and turning up the light:

If you turn on and turn up the light, fatigue will lessen and performance will improve during the day or night.  At night your brain is much more sensitive to light.  All you need is between 750 and 1,000 lux to reverse the drop in alertness and performance [7] that normally occurs when the brain thinks it is time to sleep. During the day you will probably need brighter light to experience the same effects.

There are two cautions that must be mentioned when it comes to using bright light as a fatigue countermeasure.  First, it is unclear how long the effects of bright light last after you turn off the light. This means you cannot count on a five minute dose of light to keep your fatigue at bay and your performance high for hours after you turn off the light.  To be safe, keep the light on.  Second, exposure to a narrow band of blue light at night can be harmful to your health.  This band of blue light is found in full spectrum light, which covers most light including sunlight. To be safe, wear glasses that filter out close to 100% of all the blue band of light at night.

Caffeine and energy drinks:

This is another straight forward one. Caffeine in doses of 80 to 200 mg reduces how fatigued you feel and can bring your performance back up to safe level[8].  Plus, it can do so for three or four hours with just one dose (e.g., 80 to 200 mg) depending on your sensitivity to caffeine. But don’t let the energy drink people fool you, all the other “stuff’ they put in energy drinks, like taurine, sugar, B vitamins, guarana, etc. has no effect on fatigue or performance[9]. This means that a cup of coffee is just as good as a Red Bull.

The Take Home Message

If you are going to use a strategy that you think makes you feel less fatigued, be sure to combine it with caffeine or bright light.  This should bring your performance back up to a satisfactory level and keep you safer.

References

[1] Donlea, J., Alam, M., & Szymusiak, R. (2017). Neuronal substrates of sleep homeostasis; lessons from flies, rats and mice. Current Opinion in Neurobiology, 44, 228–235.

[2] See for example:  Wesensten, N., Balkin, T., & Belenky, G. (2015). Countermeasures for mitigating fatigue in motor vehicle operators.  Reviews of Human Factors and Ergonomics, 10, 115-137.

[3] Fatigue will impair many facets of human performance.  Impairments include reductions in cognitive, attentional and memory performance, see for examples:

(A) Dinges, D., Pack, F., Williams, K., Gillen, K., Powell, J., Ott, G., Aptowicz, C., & Pack, A. (1997). Cumulative sleepiness, mood, disturbance, and psychomotor vigilance performance decrements during a week of sleep restricted to 4-5 hours per night. Sleep, 20(4), 267-277.
(B) Ingre, M., Åkerstedt, T., Peters, B., Anund, A. & Kecklund, G. (2006). Subjective sleepiness, simulated driving performance and blink duration: Examining individual differences. Journal of Sleep Research, 15, pp. 47-53.
(C) Pilcher, J., & Huffcutt, A. (1996) Effects of sleep deprivation on performance: A meta-analysis. Sleep, 19(4), 318-326.

[4] 

(A) Reyner, L., & Horne, J. (1998). Evaluation “in-car” countermeasures to sleepiness: Cold air and radio. Sleep, 21, 46-50.
(B) Schwarz, J., Ingre, M., Fors, C., Anund, A., Kecklund, G., Taillard, J., Philip, P., & Åkerstedt, T. (2012). In-car countermeasures open window and music revisited on the real road: Popular but hardly effective against driver sleepiness. Journal of Sleep Research, 21, 595-599.

[5] See for example: Allen, A., & Smith, A. (2012). Effects of chewing gum and time-on-task on alertness and attention.  Nutritional Neuroscience, 15, 176-185.

[6] Kohler, M., Pavy, A., & van den Heuvel, C. (2006). The effects of chewing versus caffeine on alertness, cognitive performance and cardiac autonomic activity during sleep deprivation. Journal of Sleep Research, 15, 358-368.

[7] Campbell, S., & Dawson, D. (1990). Enhancement of nighttime alertness and performance with bright ambient light. Physiology & Behavior, 48, 317–320.

[8] See for example:  Wesensten, N., Balkin, T., & Belenky, G. (2015). Countermeasures for mitigating fatigue in motor vehicle operators.  Reviews of Human Factors and Ergonomics, 10, 115-137.

[9] McLellan, T., & Lieberman, H. (2012). Do energy drinks contain active components other than caffeine? Nutrition Reviews, 70, 730-744.