Canadian study outlines the risks of shift work

A new study explored the risks of shift work and is providing more proof that it is bad for you.

Published in the January 2016 edition of the Journal of Occupational & Environmental Medicine, the study looked at body composition of shift workers and found that compared to people working regular days, shift workers had lower aerobic capacity, even when their physical activity matched that of regular workers.

An increasingly common fixture of the modern life, shift work is being put under the microscope in any number of ways, highlighting its detrimental effects on workers’ health. Rates of workplace injury, cancer, diabetes, cognitive impairment, obesity and heart disease are just some of the factors that are affected by shift work, where the body’s natural rhythms are disrupted in order to get in a day’s work.

Led by Sarah E. Neil-Sztramko of UBC’s School of Population and Public Health, the new study analyzed data from the Canadian Health Measures Survey to come up with its comparison of shift workers and day workers. Surprisingly, even when shift workers were known to have fewer sedentary minutes over the course of their work week, the results still indicated their comparatively lower aerobic capacity.

“This analysis confirms previous findings that shift workers have poorer body composition than day workers and suggests that shift workers may need to engage in more physical activity to achieve the same aerobic capacity as day workers,” say the study’s authors.

Shift work is generally counted as any workday that stands outside the usual 8 am to 5 pm schedule and includes both evening, alternating and night shifts. The Institute for Work & Health reports that one third of the Canadian labour force are shift workers, with heavy numbers in the food services and accommodation sectors (40% of workers) as well as in manufacturing (27%) and health care and social assistance (26%).

Shift work is more common for men than women and for the young (under 30 years of age) than for older workers. Larger companies are more likely to ask employees to work shifts than smaller ones, and shift work is more often a fact of life for the unskilled workforce than for skilled workers.

Another study this week from the University of California, Los Angeles, published in the journal eLife, outlines the extent of cognitive function impairment due to irregular work and sleep patterns. The study looked at the impact on learning and memory in mice under conditions where normal circadian rhythms were disrupted. It was found that processes of memory formation were disrupted when the mice fed at night instead of during the day. The study concluded that “chronic circadian misalignment resulted in dramatic deficits in hippocampal-dependent learning and memory,” suggesting that for humans, shift work and irregular eating times can have a deep impact on learning and memory.

Circadian rhythms are identified as the 24 hour cycle of physical, mental and behavioral processes that determine sleep patterns, body temperature and help regulate hormonal, digestive and regenerative functions.

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