How understanding body clocks can aid shift workers

Understanding the individual timing of a person’s body clock could be the key to increasing alertness in shift workers, according to a new study.

Researchers at the Alertness CRC examined 52 nursing and medical staff in an intensive care unit at Austin Health (Victoria) as they worked on a variety of shifts — day, evening and night.

Shift work has long been associated with impaired alertness and performance, which can further lead to poor staff health and increased workplace errors. The researchers found maintaining alertness during a night shift is linked with understanding how a worker’s body clock functions.

“We’ve uncovered new knowledge on the impact of different shift types and the sleep-wake behaviour of healthcare shift workers, which could inform potential methods of intervention to help people cope better with shift work,” said Monash University’s Dr Tracey Sletten, an Alertness CRC Project Leader and senior author on the paper, published in Scientific Reports.

During the study, sleep and wake duration between the workers’ shifts was evaluated using wrist activity monitors and daily diaries. As expected, the amount of sleep obtained during the day between night shifts was shorter than most people require. An additional significant finding was that working early morning shifts was also associated with a considerable reduction in sleep.

“We found that in rotating shift workers, early day shifts could be associated with similar sleep loss to night shifts, particularly when scheduled immediately following an evening shift,” Sletten said.

“This is important to consider when designing shift schedules to optimise the sleep, alertness and the wellbeing of staff in any industry.”

The study also assessed the time course of alertness and performance during day and night shifts, specifically examining whether alertness is most impaired on the first night shift or after working several consecutive nights.

Staff reported their level of sleepiness and completed tests of reaction time and attention during day shift, as well as on the first night shift, and after several consecutive night shifts.

“Workers experienced higher sleepiness and had slower reaction times at the end of night shifts compared to day shift,” Sletten said.

Unlike many other similar studies, this study also involved the collection of biological samples, to assess the specific timing of individual staff’s circadian phase — the timing of their body clock — to examine the impact of this timing on changes in alertness and performance during a shift. Circadian timing varied considerably between individuals, and this timing was shown to influence sleepiness and performance during night shifts.

“We can now use this information to inform potential interventions to improve sleep obtained by shift workers,” Sletten said. “In turn, we hope that this will have a positive impact on the personal health of these workers.”

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