Tired of fatigue?

Sleep deprivation issues are not confined to EMS. It is estimated that 20% of the workforce has irregular, rotating, or unstable shifts. Astronauts on the International Space Station took computerized tests to determine mental acuity after a workday and found that tasks like adding strings of small numbers were difficult to complete. Some scientific labs have policies that limit the use of e-mails during long night shifts. The length of our day and duration of our activities are not confined to our work schedules. The additive effects of these phenomena have resulted in a condition called social jet lag. The way we live puts us out of synchrony with our natural circadian rhythms. Add social jet lag to the physical and mental stressors inherent in EMS and the result is widespread fatigue.

In a recent JEMS article, Dr. Daniel Patterson cited a definition of fatigue as “a subjective, unpleasant symptom, which incorporates total body feelings ranging from tiredness to exhaustion creating an unrelenting overall condition which interferes with an individual’s ability to function to their normal capacity.” More complicated than just tired isn’t it? Our sleep pattern is governed by circadian rhythmicity. Circadian comes from the Latin word “circa dies” which means about a day. The approximate 24 hour light-darkness cycle results from the earth spinning on its axis. The body uses sensory information to tune our internal circadian clocks. In other words is it night or day? Is it time to eat? How do you know?

Intrinsically sensitive retinal ganglion cells, which have the primary job of light detection, not image formation, connect to the suprachiasmatic nucleus (SCN). The SCN, composed of thousands of neurons, has and generates rhythms within itself and shares them with the rest of the body. Almost every cell in the body has a circadian rhythm. It is critical for the rhythm of the SCN cells to be in synchrony with the rhythms of the other cells. Disruption of circadian rhythmicity has been associated with depression, dyslipidemias, autoimmune disorders, hypoinsulinemia, insulin resistance, chronic stress, neurodegeneration (i.e. Alzheimer’s, Parkinson’s, Huntington’s Diseases), thromboembolic events, obesity, irritable bowel disease flares and tumorigenesis.

Sunlight is the most effective stimulus for the circadian clocks. Surprisingly, the blue light from LED screens on smart phones or tablets seen prior to an attempt at sleep can delay the circadian response and disrupt sleep. The retinal ganglion cells are particularly sensitive to blue light.  It is clear that this complicated, sensitive mechanism affects our entire body. We obviously cannot function safely when this system is impaired. Have you ever made a clinical error or had a driving induced near death experience because of fatigue? What can we do?

Dr. Patterson at the University of Pittsburg Department of Emergency Medicine worked with NASEMSO and more than a score of investigators to review 38,000 pieces of literature. They used formal scientific methods to develop recommendations specific to EMS. One recommendation is that EMS organizations use survey instruments to measure and track fatigue among personnel. Some technological help, which we are naming, not endorsing, can be found at mycircadianclock.org, entrain.math.lsa.umich.edu and justgetflux.com.

The panel recognized that shift duration is complex, but recommended shift durations less than 24 hours. Back-to-back shifts that are less than 24 hours, but result in a 24 hour duration when worked in sequence, should be considered a 24 hour shift. Caffeine should be available as a fatigue counter-measure. Crews should have permission, access and opportunity to sleep on duty. The final recommendation is that everybody in the EMS system should receive training and education about sleep health, the dangers of fatigue and how to mitigate them.

Services need a fatigue risk management system. The system must be specific, measurable, achievable, realistic and timely (SMART). We must meet the needs of our patients in a manner that allows our service to survive financially. This fiscal imperative must be coupled with an approach that removes fatigue as an acute risk factor that precipitates crashes and clinical errors, as well as a risk factor for chronic conditions that impair the health and well-being of caregivers.


  • Patterson D, “Dead Tired: Evidence-based recommendations for combatting fatigue in EMS” JEMS, February, 2018, pp. 26-35.
  • Webb A, Herzog E, “Adapting your body clock to a 24-hour society”, American Scientist, Vol 105, November-December, 2017, pp 348-355.
  • Musick E, Holtzman D, “Mechanisms linking circadian clocks, sleep and neurodegeneration” Science, Vol 354, Issue 6315, 25 November, 2016, pp 1004-1007.
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