In particular, the researchers from Uppsala University found that compared to non-shift workers, shift workers needed more time to complete a test that is frequently used by physicians to screen for cognitive impairment.
However, their study also discovered that those who had quit shift work more than five years ago completed the test just as fast as the non-shift workers.
This implies that the damage caused by irregular hours can be reversed if people are willing or able to stop doing it.
The goal of their study was to examine whether shift work history could be linked to performance.
“Our results indicate that shift work is linked to poorer performance on a test that is frequently used to screen for cognitive impairment in humans,” said Christian Benedict, associate professor at the Department of Neuroscience at Uppsala University and corresponding author of the study.
Benedict added that poorer performance was only observed in current shift workers and those who worked shifts during the past five years.
“In contrast, no difference was observed between non-shift workers and those who had quit shift work more than five years ago,” he said.
“The latter could suggest that it may take at least five years for previous shift workers to recover brain functions that are relevant to the performance on this test.”
The test that was used involves two parts and is called the "Trail Making Test".
Part A had participants connecting circles labelled with numbers 1-25 in an ascending order.
In part B, people had to alternate between numbers and letters in an ascending order.
The test involved input from around 7000 participants.
Poor concentration, trouble learning new things, and bad memory are just some of the symptoms of shift work involving irregular hours.