Nurses appear to be at higher risk of injury as they suffer a kind of cumulative fatigue and diminishment in balance and reactions working “compressed” shifts, researchers report.1

Regardless of day or night shift, nurses working three 12-hours stints within a four-day period showed measurable diminishment in motor skills and increase in musculoskeletal disorders, the study found. The overall effect of this fatigue heightens risk for injury by slips and falls while putting patients at risk of medical errors.

“Evidence is mounting that the more rigorous work schedules yield unfavorable effects on the worker and on the quality of care,” says lead author Brennan J. Thompson, PhD, assistant professor of kinesiology at Utah State University in Logan. “More effort is needed to regulate the volume of work performed within a given time period.”

Some researchers argue that 12-hour shift schedules are a major part of the problem, suggesting that shorter work shifts would help resolve some of the poor health and work-related issues of nurses, he says.

“If the 12-hour shift schedule is unable to be avoided, efforts should be made to spread the work shifts across a longer time period, allowing greater recovery between shifts,” Thompson says.

For example, nurses could consider spreading their shifts across a greater number of days, such as working three shifts over a five-to-seven-day period.

“It may be prudent for nurses to work no more than two shifts in a row and to allow a minimum of two days of recovery days off following two work shifts,” he says. “Fatigue, and ultimately burnout, occur when there is an imbalance of work volume performed relative to recovery.”

For successive shifts — two or more — one day off for recovery is likely insufficient to restore performance. If recovery time is lacking, chronic fatigue may set in along with impaired mental and physical performance on a long-term basis, he warns.

Sticking strictly to the science, it is not possible to say exactly what is causing the problem or account for all variables between day and night shifts. Regardless of shift, nurses working three 12-hours stints within a four-day period showed measurable diminishment in motor skills and increase in musculoskeletal disorders. This corrected the original hypothesis to some degree, as researchers thought night shift workers would have increased musculoskeletal disorders or poorer response times than their day shift colleagues.

“Our study findings did not show differences in fatigue responses between day and night shift workers for a time-matched work intervention,” Thompson says. “This may suggest that fatigue develops in nurses independent of the type of shift worked, when working long hours in a successive work shift pattern.”

However, this does not pinpoint the exact sources of the fatigue, so “the possibility remains that unique characteristics to each shift type are contributing differently to the similarly observed performance declines,” he says.

The prevailing but unproven theory is that workers on compressed shifts lack “recovery time,” and thus suffer diminished abilities as they wear down, he says.

“The current body of research is not complete in this regard,” Thompson says. “More work is needed to identify and characterize the root causes of worker fatigue as a result of demanding work schedules. An appealing hypothesis is the lack of opportunity for a full recovery of performance prior to the next successive shift.”

It’s certainly an area in need of some answers, as nurses are an unfortunate No. 1 annually when non-fatal occupational injuries are tallied. In addition, only workers in the warehouse and transportation sector have more musculoskeletal disorders than nurses.

“This alarming statistic is particularly impactful when considering that the healthcare industry comprises one of the largest portions of the labor force (12%, 17 million workers), and is projected to experience the highest growth of any other industry in the upcoming years — adding 5 million jobs through 2022,” Thompson and co-authors reported in the paper.

The most commonly reported injuries in nurses are of the musculoskeletal variety, with leading causes including overexertion, slips, trips, and falls. Delayed response and fatigue impairments could hinder rapid responses needed to recover from a slip or a sudden patient movement that could result in a needlestick or other injury.

“[T]hese predominant causes of injury may be largely preventable, particularly because they are factors that are influenced by the individual-environment dynamic,” the authors reported. “For example, improvements in individual health and performance abilities [through] reduced fatigue, improved body mass index, enhanced response time, muscular strength, [in addition to better] work scheduling patterns, availability of mechanical lifting aids, etc., would likely diminish risks.”

The researchers used a questionnaire to find the prevalence of musculoskeletal disorders and fatigue effects. Nurses working three 12-hour work shifts in a four-day period were then tested for balance, reaction time, and other measures after the work period.

“A key feature of this study was that these changes were demonstrated objectively using physical performance-based measurements, and not solely based off of self-reported or perceived functional status,” the authors concluded.


  1. Thompson BJ, Stock MS, Banuelas VK, et al. The Impact of a Rigorous Multiple Work Shift Schedule and Day Versus Night Shift Work on Reaction Time and Balance Performance in Female Nurses: A Repeated Measures Study. Jrl Occ Environ Med 2016;58(7):737-743.