According to a study in the journal occupational and environmental medicine, working shifts for long-term has an ageing effect on the brain impairing the ability to think and remember and doing so for at least a decade the brain by an extra six and a half years.
Other studies have suggested links with cancers, heart attacks, strokes, ulcers and metabolic diseases such as diabetes.
Researchers from University de Toulouse and Swansea University studied 3,000 people in south-west France who were either working, or had retired, in 1996, 2001 and 2006.
People who had worked rotating shifts (a mixture of mornings, afternoons or evenings) for 10 years or more also had poorer mental function than those who had not done so to the extent that they had suffered an extra 6.5 years of age-related cognitive decline, the scientists found.
There was some recovery after people stopped working antisocial shifts, but it took five years to return to normal.
Other studies have linked vitamin D deficiency due to reduced exposure to sunlight to poorer mental ability.
Writing in the journal Occupational and Environmental Medicine, the international team led by Dr Jean-Claude Marquie, from the University of Toulouse, France, concluded, “Shift work chronically impairs cognition, with potentially important safety consequences not only for the individuals concerned, but also for society.”
Shift workers had lower average scores for memory, processing speed and overall brain function than those working normal office hours.
Compared with people who had never worked rotating shifts, participants employed this way for 10 or more years had lower overall thinking and memory scores.
The researchers said, “Measures should be considered that mitigate the impact that prolonged exposure to shift work has on cognitive abilities, including switching to normal day work.”