Former shift workers may need 5 years to ‘recover brain functions,’ researchers say

Uppsala, Sweden – A study of current and former shift workers shows that shift work may contribute to cognitive difficulties that take years to recover from, according to researchers at Uppsala University and Malmö University.

Using the Swedish cohort study EpiHealth, researchers examined the data of about 7,000 people ages 45 to 75 who self-reported their shift work history. Participants took the “Trail Making Test” used to measure cognitive function, which is believed to decrease with age.

During the first part of the test, the participants connected circles marked 1 through 25 in ascending order. For the second part, participants were asked to switch between numbers and letters in ascending order. Results showed that both current shift workers and people who had performed shift work during the previous five years scored worse on the test, and required more time to finish it, than non-shift workers. In contrast, researchers found no difference between the performance of workers who quit shift work more than five years ago and non-shift workers.

The findings indicate that former shift workers may need at least five years to “recover brain functions” related to the test, according to the researchers, who speculate that sleep problems associated with shift work may contribute to diminished work performance.

“Since short sleep has been associated with learning and memory impairments, it could therefore be hypothesized that short sleep duration, in combination with circadian disruption, may further restrain performance on the [test] in shift workers,” the researchers wrote in the study.

The study was published online May 14 in the journal Neurobiology of Aging.