People who undertake shift work for 10 years or more may suffer loss of memory and brain power.
The research published in Occupational & Environmental Medicine asserts that shift work disrupts the body's internal clock and has previously been linked to health problems like ulcers, cardiovascular disease and some cancers.
The effects on brain function can be reversed, but it may take at least five years.
Researchers tested more than 3000 current or retired workers in a variety of sectors in southern France in 1996, 2001 and 2006 for long and short-term memory, processing speed and overall cognitive abilities.
About half of the trial subjects - aged either 32, 42, 52 or 62 when they were first tested - had worked shifts, classified as night work or shifts that alternated between morning, afternoon and night.
The study could not prove conclusively that shift work was the cause of the cognitive decline, said the authors, and though it seemed "highly plausible", further research was needed.
According to the Australian Bureau of Statistics about 1.4 million Australians are in shift work, making up 16 per cent of employees.
About 68 per cent of shift workers are full-time and 55 per cent were men.
