Heart attack and stroke risk may double with irregular bedtimes and under 8 hours of sleep

A long-term study of 3,231 adults in Finland found that people with irregular bedtimes who slept less than eight hours had nearly double the risk of a major cardiovascular event over the following decade. The study used wrist activity monitors for sleep measurement and national health records to track heart attack, stroke, and cardiovascular deaths.

Researchers in Finland examined the relationship between sleep timing, sleep duration and major cardiovascular outcomes in a long-term cohort study. The team analyzed wrist actigraphy and health data from 3,231 participants in the Northern Finland Birth Cohort 1966 and used the first seven consecutive nights of sleep data. They tracked heart attack, stroke and cardiovascular-related deaths in national health records over the next 10 years. The study, published in BMC Cardiovascular Disorders, observed that irregular bedtimes combined with sleeping under eight hours were associated with higher cardiovascular risk. Key findings: - Participants with irregular bedtimes who slept less than eight hours had nearly double the risk of major adverse cardiovascular events (MACE) over ten years compared with those with more consistent schedules. - Highly irregular sleep midpoints showed a similar increase in cardiovascular risk, reflecting instability in circadian timing. - Irregular wake-up time on its own was not found to be associated with increased cardiovascular risk. - Data came from 3,231 adults who wore wrist activity monitors for up to two weeks; the analysis used the first seven consecutive nights of data. - Researchers identified heart attack, stroke and cardiovascular deaths using national health records during a 10-year follow-up. - The Centers for Disease Control and Prevention recommends at least seven hours of sleep for adults, and prior CDC research reports that about one-third of U.S. adults get less than seven hours per night. Summary: The study reports an association between irregular bedtimes combined with under-eight-hour sleep and about a two-fold higher risk of heart attack, stroke or cardiovascular death over ten years. Outside experts and the study authors noted that circadian disruption and chronic sleep shortage can affect hormones and blood pressure. The authors suggested that sleep consistency could be an important public health focus. Undetermined at this time.