Stroke risk related to shift work may linger, researchers say

College Station, TX — Adverse health effects of shift work – including increased risk of stroke – may persist even after workers resume traditional, 24-hour circadian cycles, according to a recent study by researchers from Texas A&M University.

The researchers followed up on a 2016 study in which they looked at the performance of rats placed on simulated fixed schedules and shift schedules. They found that the shift-schedule group experienced ischemic strokes of greater severity than the other group.

For their follow-up study, the researchers placed the animals on regular, 24-hour schedules, and then waited until their midlife equivalent – the time humans are at greatest risk of experiencing a stroke – to examine the effects.

Findings showed that, even after returning to normal work schedules, the sleep-wake cycles of the shift-schedule rats didn’t fully return to normal, and those rats experienced more severe strokes than those in the control group.

“Shift work, especially rotating shift work, confuses our body clocks, and that has important ramifications in terms of our health and well-being and connection to human disease,” David Earnest, lead study author and professor in the Texas A&M Department of Neuroscience and Experimental Therapeutics, said in a press release. “When our internal body clocks are synchronized properly, they coordinate all our biological processes to occur at the right time of day or night. When our body clocks are misaligned, whether through shift work or other disruptions, that provides for changes in physiology, biochemical processes and various behaviors.”

The researchers note the findings may also apply to workers whose schedules vary by day, especially as telework remains prevalent.

“We take our work home and sometimes work late at night,” Earnest said. “Even those of us who do work regular schedules have a tendency to stay up late on the weekends, producing what is known as ‘social jet lag,’ which similarly unwinds our body clocks so they no longer keep accurate time. All this can lead to the same effects on human health as shift work.”

Earnest advises keeping a regular daily schedule of awake time, sleep time and mealtimes.

The study was published online in the journal Neurobiology of Sleep and Circadian Rhythms.