Sleeping and waking at different times is associated with an increased risk of heart attack and stroke even in people who get the recommended amount of sleep, according to a new study, CNN reported.
While most previous studies have measured the impact of sleep duration on human health, less is known about the effects of changes in the sleep cycle, researchers say.
To address this issue, over the course of 7 days, researchers tracked activity data from 72,269 participants aged 40 to 79 years who had never suffered a serious adverse cardiovascular event.
They calculated each person's sleep regularity index (SRI), with a higher score meaning more regular sleep.
The team then tracked cases of cardiovascular death, heart attack, heart failure, and stroke for 8 years and found that people with irregular sleep patterns were 26% more likely to suffer any of these diseases than those with regular sleep cycles. Irregular sleep means variations in the time a person falls asleep and wakes up.
The 26% calculation also took into account a number of factors, including age, physical activity, alcohol consumption and smoking, which could affect the results. However, this is an observational study and as such can only establish a link, not cause and effect: we cannot know for sure whether irregular sleeping patterns caused the increased risk.
The researchers also noted that people with higher SRI scores (more regular sleepers) were more likely to meet the daily recommendation of 7 to 9 hours of sleep per night for people aged 18-64 and 7 to 8 hours for people over 65, with 61% of regular sleepers meeting this recommendation compared with 48% of irregular sleepers.
But even the irregular sleepers who slept the recommended amount of sleep had a higher risk of serious cardiovascular events.
Study lead author Jean Pierre Chaput, a professor of pediatrics at the University of Ottawa in Canada, said that "a growing body of research suggests that sleep irregularity may be a stronger predictor of mortality risk than insufficient sleep duration."
As for reducing the risk of cardiovascular events, Chaput highlighted the fact that high blood pressure is a leading risk factor.
"Readers should prioritize 7 to 9 hours of consistent, restorative sleep per night, as poor sleep can contribute to high blood pressure," he said.
"Bedtime and wake-up times don't have to be exactly the same every day, but it's good to move within 30-60 minutes of your usual schedule to maintain your body's natural circadian rhythm. Small deviations are normal, but consistent sleep patterns improve sleep quality, boost mood and cognitive function, and reduce the risk of health problems such as heart disease and diabetes," the expert stressed.
He also cautioned against relying on catch-up sleep on weekends.
"It is possible to recover some sleep by sleeping longer on weekends, but this does not completely undo the negative effects of chronic sleep deprivation during the work week. While extra sleep on the weekend can temporarily improve mood and cognitive function, irregular sleep can disrupt the body's circadian rhythm and lead to long-term health risks such as obesity, diabetes and heart disease," added Chaput, who is currently developing healthy sleep guidelines in collaboration with the World Health Organization.
"I believe this is an important next step to ensure that sleep is valued as an essential component of well-being and not dismissed as a waste of time in our society," he said. | BGNES
