Shift work linked to cognitive declines

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Nursing home staff on shift schedules might experience diminished memory and thinking skills, recently published findings suggest.

People who did shift work for a decade or longer had lower scores on memory, thinking and processing tests than those who worked standard schedules, the investigators found. In fact, it was as if the shift workers' brains had aged an additional 6.5 years.

Even workers who had been doing shift work for less than a decade had lower scores. And it takes about five years for the brain to bounce back to age-appropriate performance after shift work ends, the study authors determined.

“Shift work chronically impairs cognition, with potentially important safety consequences not only for the individuals concerned, but also for society,” the authors wrote in the study abstract.

The study did not determine why cognitive skills would be eroded by rotating morning, day and nighttime work. Previous research has suggested that working irregular hours disrupts the body's circadian rhythms and might impair mental processes by boosting cortisol levels.  

The study involved more than 3,200 people, who ranged in age from 32 to 62 at the time of the first test. They were evaluated five and 10 years later. About 1,400 did shift work and the remainder did not. The investigators were based in Europe, with the lead author at the Université de Toulouse-CNRS in France.

Complete findings were published Monday in the online version of Occupational & Environmental Medicine.