Are staffers getting punched out on shift work?

05 November 2014 -


Long patterns of very early or very late shifts can lead to reduced memory and cognitive processing, new report shows – but damage is reversible

Jermaine Haughton

Employees who have done at least 10 years of constant shift work can expect their brain to have aged by six-and-a-half years compared to that of the average, nine-to-five worker, according to new research. Published in the journal Occupational & Environmental Medicine, the study shows that staff who have undertaken a decade or more of rotating shift patterns recorded significant cognitive decline, with thinking and memory abilities particularly blighted.

Using data from patients observed by occupational-health doctors in France, researchers analysed the cognitive skills of more than 3,000 workers aged between 32 and 62 in the years 1996, 2001 and 2006. Half of those subjects had worked as many as 50 days of shift work per year.

Much like jetlag experienced on long-haul flights, working specific morning, afternoon and night shifts causes disruption to the body’s internal clock – also known as the circadian rhythm – boosting an individual’s likelihood of developing ulcers, cancer or brain damage. Furthermore, the amount of sunlight an individual sees may also have an effect. Staff who work during the night, for example, are likely to sleep during the day, leading to a vitamin D deficiency – raising the potential for a metabolic disorder.

Report co-author Dr Philip Tucker – a specialist at the Swansea University Department of Psychology and the Stress Research Institute of Stockholm – said: “The findings suggest that work patterns should be designed so as to minimise circadian disruption. That means, for example, working only a very few night shifts in a row before reverting to day work, so that the body clock stays close to the normal diurnal cycle – rather than starting to re-adjust to a nocturnal cycle.”

He added: “Trying to adjust the body clock to night work is probably not the solution for most people. Other research suggests that even among those who work fixed night shifts, only a minority manage to sufficiently adjust their body clock to a nocturnal cycle.”

The study stops short of drawing definite cause-and-effect connections between shift work and mental decline, mainly in light of other variables, such as the differences in types of work undertaken at different times of the day. While most office jobs operate during the day, some high-risk jobs – such as security or trucking, for example – tend to done at night, suggesting that safety may be a factor in the study.

On a positive note, though, researchers say the effects on brainpower can be reversed, but that a full recovery in thinking capability could take at least five years. “The fact that the effects lasted for some years after leaving shift work is certainly interesting,” Tucker said. “Although given that we were looking at chronic effects (rather than just acute effects, such as fatigue resulting from sleep disturbance), it was not completely unexpected.

“If anything,” he added, “I was perhaps rather more struck by the finding that the effects were shown to be reversible at all – some studies by other researchers indicate that shift workers continue to experience other problems (eg, sleep disturbance) after retirement.”

Find an abstract of the research here.

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