Researchers at the University of Oulu have discovered that irregular bedtimes may pose significant cardiovascular risks. The study, published in BMC Cardiovascular Disorders, tracked 3,231 individuals born in Northern Finland in 1966. Their sleep patterns were measured over one week at age 46, and health outcomes were followed for over a decade. The findings suggest that large variations in bedtime could double the likelihood of serious cardiac events.
The study found that irregular bedtimes and greater variation in sleep timing were strongly connected to an increased risk of major cardiovascular events. This link was most evident in participants whose time in bed was under eight hours, where the risk was about twice as high compared with those who followed more consistent sleep schedules. In contrast, inconsistent wake-up times did not show a clear association with heart health.
Major cardiovascular events in the study referred to conditions requiring specialised medical care, such as myocardial infarction or cerebral infarction. The finding places the focus on repeated habit, not on whether someone simply prefers early mornings or late ones. Postdoctoral researcher Laura Nauha from the University of Oulu stated that the regularity of bedtime, in particular, may be important for heart health.
The study estimated sleep duration and timing using activity monitors that recorded how long participants spent in bed. Participants with irregular bedtimes who slept less than eight hours had twice the risk of myocardial infarction or cerebral infarction compared with those with stable schedules. Variability in the “sleep midpoint” was also strongly associated with higher cardiac risk.
According to Nauha, many factors influencing heart health are tied to daily habits, and maintaining a regular sleep schedule is one factor that most people can influence. Consistent sleep keeps the body’s circadian rhythms, its internal 24-hour clock, in sync with light, hormone cycles, and blood pressure. When bedtime shifts from night to night, that timing can become disrupted.
The biological explanation for the link between irregular bedtimes and cardiovascular risk suggests that shorter nights can worsen the strain on the heart because the body loses both recovery time and the steady schedule that guides it. This explanation fits what heart researchers already know about the importance of consistent sleep patterns for overall health.
The study’s findings highlight the importance of establishing a consistent sleep schedule to reduce the risk of cardiovascular events. By prioritising regular bedtimes, individuals can potentially lower their risk of heart health problems and maintain overall well-being. The research underscores the need for further studies to explore the relationship between sleep patterns and cardiovascular health.
Key points
- Irregular bedtimes may double the risk of serious cardiac events, particularly among those who sleep less than eight hours per night.
