Shift work increases employees' risk of stroke: Study

Employees working shifts are known to experience several health impacts including disruption of sleep patterns, mealtimes, and their ability to exercise.

Around 15 million US citizens do not work have a typical nine-to-five work schedule.

It is already known that shift workers were at greater risk of heart attacks and obesity, but according to new evidence, they could also face increased risk of brain injury.

A new study by experts at Texas A&M University had found that people working irregular hours, whose sleep and eating patterns were disturbed, were predisposed to  severe stroke.

Professor David Earnest, at Texas A&M Health Science Center College of Medicine, said, "The body is synchronized to night and day by circadian rhythms - 24-hour cycles controlled by internal biological clocks that tell our bodies when to sleep, when to eat and when to perform numerous physiological processes.

"A person on a shift work schedule, especially on rotating shifts, challenges, or confuses their internal body clocks by having irregular sleep-wake patterns or meal times."

According to professor Earnest, it was not the longer hours - or their irregular nature that was necessarily the problem.

Researchers found that shift work could lead to more severe ischemic strokes, which occurred when blood flow was cut off to part of the brain.

The researchers found that subjects on shift work schedules suffered more severe stroke outcomes, as regards both brain damage and loss of sensation and limb movement than controls on regular 24-hour cycles of day and night.

The study uncovered significant differences in the degree to which the stroke was worsened by circadian rhythm disruption, with males experiencing more serious stroke outcomes from response shift work than females.

"These sex differences might be related to reproductive hormones. Young women are less likely to suffer strokes, as compared with men of a similar age, and when they do, the stroke outcomes are likely to be less severe," said Farida Sohrabji, also from Texas A&M.

"In females, estrogen is thought to be responsible for this greater degree of neuroprotection. Essentially, estrogen helps shield the brain in response to stroke," said Sohrabji.

The journal of Endocrinology has published the findings.