People who work rotating shifts or who change sleeping and eating schedules often are more likely to have a severe stroke, a new study finds.
It’s not the longer hours—or the weird hours—that necessarily seem to be the problem, according to David Earnest, a professor at the Texas A&M Health Science Center College of Medicine. Instead, it’s the change in the timing of waking, sleeping, and eating every few days that “unwinds” body clocks and makes it difficult to maintain a natural, 24-hour cycle.
“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,” says Earnest.
When body clocks are disrupted, as they are when people go to bed and get up at radically different times every few days, it takes a toll on health.
Earnest and his team found that shift work schedules were linked to more severe stroke outcomes, in terms of both brain damage and loss of sensation and limb movement, based on research with animal models.
They also found males and females show major differences in the degree to which the stroke was exacerbated by circadian rhythm disruption; in males, the gravity of stroke outcomes in response to shift work schedules was much worse than in 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. In females, estrogen is thought to be responsible for this greater degree of neuroprotection,” says Farida Sohrabji, who collaborated on the study and also is a professor at Texas A&M.
Earnest recommends that those with irregular sleeping patterns try to maintain regular mealtimes.
“This research has clear implications for shift workers with odd schedules, but probably extends to many of us who keep schedules that differ greatly from day-to-day, especially from weekdays to weekends,” Earnest adds. “These irregular schedules can produce what is known as ‘social jet lag,’ which similarly unwinds our body clocks so they no longer keep accurate time, and thus can lead to the same effects on human health as shift work.”