Irregular sleep patterns may increase the risk of adverse cardiovascular events such as heart attacks, say researchers. (Grace Cary/Moment RF/Getty Images/CNN via CTV News)
New research suggests that irregular sleep patterns—specifically inconsistent bedtimes and wake-up times—may increase the risk of heart attack and stroke, even for those who get the recommended amount of sleep.
While previous studies have focused mainly on the length of sleep, less is known about how disruptions in the sleep cycle might affect health. In an effort to understand this better, researchers followed 72,269 participants, aged 40 to 79, who had no history of major cardiovascular events. Over the course of seven days, they monitored the participants' sleep behaviors and calculated a "Sleep Regularity Index" (SRI). A higher score indicated a more consistent sleep routine.
The study then tracked occurrences of cardiovascular problems—such as heart attacks, heart failure, strokes, and related deaths—over an eight-year period. They found that those with irregular sleep schedules were 26% more likely to experience one of these events compared to those with more regular sleep patterns. Irregular sleep was defined as fluctuating times for falling asleep and waking up.
This statistic takes into account other risk factors like age, physical activity, and lifestyle habits such as smoking and alcohol use. However, researchers emphasized that the study was observational, meaning it can only suggest a link rather than prove cause and effect. Irregular sleep patterns might contribute to increased risk, but it's unclear whether they directly cause these health issues.
Interestingly, those with more regular sleep patterns were more likely to meet the recommended sleep duration of seven to nine hours for adults under 65, and seven to eight hours for those over 65. 61% of regular sleepers adhered to these guidelines, compared to 48% of those with irregular sleep patterns. Even so, the research found that irregular sleepers who got the recommended amount of sleep still had a higher risk of cardiovascular events.
Lead author Jean Pierre Chaput, a professor at the University of Ottawa, told CNN that research is increasingly pointing to irregular sleep as a stronger predictor of health risks than sleep deprivation alone. He also noted that high blood pressure is a key factor in cardiovascular health, and consistent, restorative sleep is crucial for managing it.
Chaput recommends sticking to a sleep schedule as much as possible, with bedtimes and wake-up times varying by no more than 30 to 60 minutes each day. Regular sleep patterns not only improve sleep quality but also enhance mood, cognitive function, and reduce the risk of chronic diseases like heart disease and diabetes.
He also cautioned against relying on catching up on sleep during weekends. While it may temporarily improve mood and alertness, it does not fully compensate for the negative effects of irregular sleep during the week. Disrupting the body’s natural circadian rhythm can contribute to long-term health issues, including obesity, diabetes, and heart disease.
Naveed Sattar, a professor at the University of Glasgow, acknowledged the connection between sleep patterns and cardiovascular health but cautioned against jumping to conclusions about causality. He suggested that other factors, like late-night alcohol consumption, might influence both sleep patterns and health outcomes, making it difficult to draw definitive conclusions from the study.
The findings were published in the Journal of Epidemiology & Community Health.
