On the job alertness, fatigue and performance in EMS

Tired EMT In this third article in the Vitals series on EMS Operator Fatigue, we address notions of sustained performance as it may be affected by degraded levels of alertness, drowsiness and fatigue.

Alertness on the job

When EMS providers respond to medical emergencies they are expected to have maximum levels of alertness and performance at any time of the day or night wherever they provide around-the-clock services. What does it mean to be fully alert? Emergency scenes often require EMS providers to exhibit quick and accurate reactions, life-altering and dynamically changing circumstances regarding patients' medical conditions. EMS provider alertness means maintaining a high level of situational awareness, paying close attention to details, making crisp precise decisions regarding a patient's immediate medical needs and implementing the right mix of positive action and patient comfort. Essentially, the EMS provider's goal is to get the patient to a healthcare facility for more definitive medical care.


Fatigue is the body and mind's response to continued physical, mental activity, or sleep loss. Fatigue is characterized by a diminished ability to do work, loss of attention, slower reactions, poor response, deterioration of vigilance and alertness, impaired judgment and other similar problems. Physical fatigue can result from excessive exercising of our muscles to the point where we become tired enough that hefting a litter patient becomes a difficult chore. Perhaps more importantly, mental fatigue is witnessed as a degraded cognitive ability that goes beyond feeling drowsy, or to want to fall asleep. Mental fatigue mostly affects our speed of thinking. Such fatigue manifests as a subjective feeling of tiredness, a loss of motivation and a desire for rest. Fatigue can significantly slow down our reactions in which we do not respond fast enough. Fatigue can impair our judgment to the point that we may mistake a patient's vital sign indicators for something they are not and communicate an incorrect diagnosis of the patient's medical condition or take action that makes things worse rather than better for the patient.

Fatigue factors

Operator fatigue is brought about by a variety of factors including working extensively long hours (i.e. more than 14 hours continuously), working during our body’s two expected physiological lull periods of the day (i.e. normally 1 p.m. to 4:30 p.m. and from 1 a.m. to 5:30 a.m.), working back-to-back work shifts or changing work shift schedules that does not agree well with our body’s daily circadian physiology cycles. Most important, not obtaining a sufficient amount of sleep on a daily basis.

Circadian rhythms (CR)

Most of us work during the day and we sleep best in the dark of night. Generally, that means we strive to obtain 7-8 hours of sleep at night and work anywhere from 8-12 hours during daylight. We attempt to remain fully alert at work all day, but we notice that in the middle of every afternoon, for about a half hour somewhere during the 1 p.m. to 4:30 p.m. timeframe we normally experience a sense of tiredness, a drop in mood and attitude and a decrease in our performance ability in any task we are attempting. This is known as the Circadian Rhythm (CR) physiological lull of the afternoon a time during which our body's internal core temperature has dropped slightly. Accompanying that drop in body temperature attention level is lower, reactions are slower and our overall performance on almost any task may drop about 4-10% from what it might have been in mid-morning. Likewise, if we happen to be working through the night, our body experiences another slightly larger drop in core temperature for a short while somewhere between about 1:00 a.m. and 5:30 a.m. If we are awake and working during this time our middle-of-the-night performance might degrade as much as 10-15% depending upon how much sleep we obtained during the previous day or two.

These two daily CR lulls are inescapable and they can be detrimental to our performance. It is important that EMS providers recognize these CR biological facts and plan accordingly. Be sure to look for the telltale signs of decreased mood, onset of tiredness, lessening of attention to important details at the two lull periods of the 24-hr clock. Recognize CR effects in your colleagues or EMS teammates. Note that their lull periods may not coincide precisely with yours. Discuss with them the likely effects on your important work activities. Knowledge of these inescapable CR effects is the first step toward ensuring good performance throughout the day.

Additionally, since we find it easier to go to sleep when our body's core temperature is dropping taking a 45-minute nap during the mid-afternoon makes practical sense. If one works through the night plan to take a work-break, a cup of caffeinated coffee or a nap during the after-midnight CR lull. But if you nap longer than 45-minutes you may fall into the deep phases of sleep and upon awakening you must be aware of impending sleep inertia.

Lastly, it is worth pointing out that after the mid-afternoon CR lull one's body temperature begins to rise again (i.e. after about 5:30 p.m.). This temperature rise is usually accompanied by a time of heightened alertness. While our body's core temperature is rising the early evening hours actually are a good time to accomplish work that requires high levels of alertness.

Scheduled work shifts

There are many biological, physiological and performance variables involved in critiquing work shift schedules. Generally, many forms of cognitive performance begin to exhibit performance decrements after about 14-18 continuous hours on the job. Taking rest breaks from the work place are important remedies. But the point is that working back-to-back successive shifts whether due to outside jobs or simply working two successive shifts at your normal job brings with some performance risk in terms of errors, mistakes and simply not accomplishing as much work as work progress slows down.

Another factor to consider is that rotating work schedules in a forward direction with the clock often results in better performance than does rotating one's shifts in a backward direction against the clock. In general terms, that means after working a daytime shift for a week or two it is preferred next to work the swing shift for a few weeks before changing to the midnight shift. That switching forward with the clock avoids some of the adverse biological effects commonly experienced in many factory workplaces where workers are asked to work day shifts, followed by midnights and then switch to swing shifts. Those factory shift-workers often experience significant bouts of shift lag akin to the jet lag one experiences when flying from the USA to Europe as one's body promptly finds itself out of sync with the earlier sunrise overseas. A shift-worker who shifts against the clock has to get out of bed at least 8 hours earlier on each change of report-to-work shift times. It may sound complicated, but the idea expressed in this paragraph is rather simple – when possible rotate your work shift forward with the clock and not backwards against the clock.


All persons involved in EMS operations should understand what operator fatigue is, how it adversely affects on-the-job alertness about daily rhythmic cyclic changes in our fatigue levels and the interactions with various work shift schedules.

Next newsletter issue: Effects of work settings and organizational factors on EMS provider fatigue

About the Authors:

Billy Rutherford, MS, President of American Integrated Training Systems, Inc. has managed the development of the USDOT Emergency Vehicle Operator Course (Ambulance). Billy also managed the development of over 500 hours of Pre-Hospital Computer/Internet Based training. He has been conducting EVOC Train-the-Trainer Courses Nationwide for over 20 years. Billy serves as an Expert Witness on cases where there was a serious injury or death when an emergency vehicle was involved.

Gerald P. Krueger, Ph.D., CPE, a research psychologist, is also a certified ergonomist who has spent much of the last 20 years examining issues of commercial driver alertness and driver fatigue (i.e., truck and bus drivers). Jerry has published numerous articles, and taught courses for DOT on driver fatigue and health and wellness. He also serves as an expert witness on cases of driver fatigue and driver performance.

In an attempt to stay abreast of NHTSA progress on their research initiative, Billy Rutherford and Jerry Krueger are participating in periodic EMS stakeholders’ meetings on these important topics to all EMS providers.

Tired EMT
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