French research suggests that irregular working patterns may cause long-term damage to mental abilities and memory.
Shift work causes disruption to the body’s internal clock in a similar fashion to jet lag. It has previously been linked to increased health problems, such as heart disease and potentially certain cancers.
Scientists have now discovered a connection between a decline in brain function and shift working, particularly among those who work on a rotation basis between night, morning and afternoon.
The study included 3000 people living in France, and scientists discovered that those working rotating shifts performed worse in cognitive and memory speed tests than those who worked regular hours. The decline in cognitive ability in those who had worked irregular shifts for 10 years was equal to six and a half years of natural, age-related cognitive decline.
The researchers based at Swansea and Toulouse Universities are not clear on how shift work impacts on brain function.
It is known that disruptions to the circadian rhythm, or body clock, affect the mind and the body. People who regularly go on long-distance flights have been known to suffer from declines brain function. Scientists are of the opinion that this caused by a breakdown of some brain structures, which is the result of an over-production of stress hormones.
They believe that a similar mechanism may be present in people who work alternating day and night shifts for long periods of time.
It has been suggested that those who work night shift may be more prone to vitamin D deficiencies due to reduced sunlight exposure. Vitamin D deficiency has previously been linked to impaired brain function.
The French study involved following up 1200 of the research participants at three different points, during 1996, 2001 and 2006. One in five of the participants had been working rotating shift patterns.
It was discovered that those who were currently or had previously worked shifts scored lower on processing ad memory speed tests than the ones who worked normal office hours.
Researchers discovered that when shift work was terminated there was an improvement in cognitive function. This is suggestive that the ill effects can be reversed, however it required around five years of normal working hours for an impact to be noticed.
The lead author of the research, Dr Jean-Claude Marquié, based at the University of Toulouse, said that the results of their study indicate that the health of shift workers should be closely monitored.
The report stated that the cognitive impairment observed in the study could have crucial safety consequences for society as a whole, particularly bearing in mind the increase in the number of jobs in high-hazard situations which are done during the night.
It stated that it could affect the quality of life of shift workers as regards everyday activities which depend on cognitive resources being available.
The researchers stated that their findings place focus on the importance of medical surveillance of shift workers, particularly those who have been doing it for a decade or more.
Image Credit: Allan Ajifo