Impact of Irregular Sleep on Heart Health
Failing to maintain a consistent sleep schedule increases the risk of heart-related issues, including stroke, heart attack, and heart failure, by 26%, even for those who get a full night’s sleep. This finding comes from the most comprehensive study of its kind, published in the Journal of Epidemiology and Community Health.
Previous Focus on Sleep Duration
Past research has mainly looked at the link between sleep duration and health outcomes, with the general recommendation being to get between seven and nine hours of sleep each night. While this advice remains relevant, new research is shifting focus toward the timing of sleep, particularly the effects of irregular sleep patterns.
Irregular Sleep Linked to Higher Health Risks
The study shows that irregular sleep—where bed and wake-up times vary significantly from day to day—is strongly associated with a higher risk of cardiovascular events. Even if a person sleeps for eight hours, the harmful effects of inconsistent sleep patterns remain. The study involved 72,269 adults aged 40 to 79, from the UK Biobank study, and found that even small variations in sleep timing could elevate health risks.
Recommended Sleep Patterns
Jean-Philippe Chaput, lead author of the study, recommends maintaining consistent bed and wake-up times, ideally within a 30-minute window. He explained that sleep times that deviate by more than an hour each day could lead to adverse health effects. While occasional irregular sleep, like one or two days a week, is not detrimental, frequent irregularity can lead to chronic health problems.
Waking up at the same time each day is considered more important than going to bed at the same time, as it helps regulate the body’s internal clock.
Sleep Regularity Index (SRI) and Study Method
Participants in the study wore activity trackers for seven days, and researchers calculated a Sleep Regularity Index (SRI) for each person. The SRI score measured day-to-day variations in bedtime, wake-up time, sleep duration, and wakefulness during the night. Participants were categorized based on their SRI score:
- Irregular sleep (SRI below 71.6)
- Moderately irregular sleep (SRI between 71.6 and 87.3)
- Regular sleep (SRI above 87.3)
The study tracked the participants for eight years to assess their health outcomes.
Link Between Sleep Irregularity and Health Risks
The study found that irregular sleepers were 26% more likely to experience heart attack, stroke, or heart failure compared to those with regular sleep patterns. Those with moderately irregular sleep had an 8% higher risk. Interestingly, the more irregular a person’s sleep pattern, the higher their risk of cardiovascular issues.
Sleep Duration Alone Is Not Enough
While the study confirmed that the recommended sleep duration is important (7-9 hours for adults aged 18-64 and 7-8 hours for those over 65), the timing of sleep appeared to be a more significant factor in heart health. Even those who met the sleep duration recommendations but had irregular sleep patterns were at a higher risk of heart-related events. Conversely, moderately irregular sleepers who got adequate sleep had lower risks.
Study Limitations and Conclusions
Though this study was observational and cannot definitively establish causality, it suggests a strong association between irregular sleep and an increased risk of heart issues. Researchers concluded that maintaining regular sleep patterns might be more important for cardiovascular health than simply getting enough sleep.
In summary, this study highlights that sleep regularity plays a crucial role in reducing the risk of major cardiovascular events, making it essential to maintain a consistent sleep-wake schedule.
