A new study suggests that maintaining consistent sleep schedules may reduce the risk of heart disease and stroke. Researchers found that irregular sleep patterns are associated with a higher likelihood of serious cardiovascular events, even among individuals who get enough sleep each night.
The study examined 72,269 participants aged 40 to 79 from the UK Biobank, tracking their health over eight years for incidents such as heart attacks, strokes, and heart failure. None of the participants had a prior history of major cardiovascular events, heart disease, or stroke at the outset of the research, according to Medical Dialogues.
Participants wore activity trackers for a week to record their sleep and wake times. Using this data, researchers calculated each person's Sleep Regularity Index (SRI) score, which measures the consistency of sleep patterns. A higher SRI score indicates more regular sleep-wake cycles. Those who went to bed and woke up at the same time every day scored 100, while individuals with highly irregular sleep schedules scored closer to zero, as reported by The Guardian.
The findings revealed that individuals with irregular sleep patterns had a 26% higher risk of experiencing serious cardiovascular events, including heart attacks, strokes, or heart failure. This increased risk persisted regardless of whether the recommended sleep durations were met. Medical Dialogues reported an almost linear relationship between sleep irregularity and cardiovascular risk, emphasizing the importance of consistent sleep habits.
Professor Jean-Philippe Chaput, the study's lead researcher and a professor of pediatrics at the University of Ottawa, highlighted the significance of regular sleep schedules. "For optimal health, it is advisable to go to sleep and wake up at the same time every day, with a deviation of no more than 30 minutes," he said, according to The Guardian. He added, "Waking up at different hours every morning disrupts your internal clock and that can have adverse health consequences."
The study showed that even individuals who slept the recommended seven to nine hours per night faced increased cardiovascular risks if their sleep schedules were irregular. Irregular sleepers could not mitigate the risk of heart attack and stroke simply by achieving sufficient sleep duration, as reported by O Globo.
Researchers noted that irregular sleep disrupts circadian rhythms and triggers hormonal imbalances, inflammation, and metabolic disorders, all of which elevate cardiovascular risks. Il Giornale reported that these harmful effects may stem from the development and maintenance of low-grade inflammation in the body.
"It is not clear exactly how sleep benefits the heart but research suggests that disturbed sleep is associated with higher levels of a protein called CRP. This is a sign of inflammation, the process linked with heart and circulatory disease," said Emily McGrath, senior cardiac nurse at the British Heart Foundation, according to a report by The Independent. She added, "Sleep can also have an indirect impact on heart health, by affecting our lifestyle choices."
The researchers acknowledged that the study was observational and could not establish causation. They also identified limitations, such as assessing sleep patterns over a single week and using activity trackers that could not distinguish between sleep and quiet wakefulness. Medical Dialogues noted that these factors might affect the accuracy of the SRI scores.
Despite these limitations, the study underscores the potential importance of sleep regularity over sleep duration in reducing cardiovascular risk. According to CNN in Spanish, the researchers suggested more attention should be paid to sleep patterns in public health guidelines and clinical practice due to their impact on heart health. "Our results suggest that sleep regularity may be more relevant than sufficient sleep duration in modulating major adverse cardiovascular event risk," they stated.
"If you need to catch up on sleep you lost during the week on weekends, then going to bed earlier is better than lying in. You should still try to wake up at the same time, even on Saturdays and Sundays," said Chaput, according to The Guardian. He emphasized that even small variations can have effects, noting, "Within an hour of the same time is good but less good than 30 minutes, and even better is to have zero variation."
The study highlights that both the quantity and quality of sleep are important, but maintaining a consistent sleep-wake schedule might be more beneficial for heart health than simply increasing sleep hours. The Scottish Sun reported that regular sleep patterns can improve sleep quality, boost mood and cognitive function, and reduce the risk of health problems like heart disease and diabetes.
Cardiometabolic medicine professor Naveed Sattar, who was not involved in the research, urged caution in interpreting the findings. "It's very difficult to say," he told CNN in Spanish, adding, "I would be cautious in attributing causality here." He suggested that other lifestyle factors contributing to irregular sleep patterns might also influence cardiovascular risk.
The article was written with the assistance of a news analysis system.