Bedtime irregularity and short sleep may increase heart attack risk

A Finnish wearable-device study of more than 3,000 middle-aged adults followed for nearly 10 years found that irregular bedtimes and variable sleep midpoints were associated with higher rates of major cardiovascular events when average sleep was under eight hours; averaging more than eight hours appeared to weaken that association.

Finnish researchers tracked sleep timing and cardiovascular outcomes for nearly a decade in a cohort of more than 3,000 middle-aged adults using wearable devices. The team measured variability in three timing measures: bedtime, wake-up time and the sleep midpoint. They reported links between irregular sleep timing and later major cardiovascular events, and noted that average sleep duration influenced those associations. Key findings: - The study followed over 3,000 middle-aged Finnish adults for about 10 years using wearable sleep trackers. - Greater variability in bedtime and in the sleep midpoint was associated with higher rates of major cardiovascular events among participants whose average sleep was under eight hours. - Averaging more than eight hours of sleep was reported to reduce the association between timing variability and heart issues. - Variability in wake-up time showed little apparent effect in this analysis. Summary: The reported results indicate an association between sleep-timing irregularity and increased major cardiovascular events, primarily among people averaging less than eight hours of sleep. Undetermined at this time.