- A new study examined the association between sleep habits and heart disease.
- After getting 7 days of sleep data from the participants, the researchers used the following 10 years of health data to examine the impact sleep habits can have on heart disease.
- They found that adults who did not keep a consistent sleep schedule and got under 8 hours of sleep had a higher risk of a major cardiovascular event (MACE).
Maintaining a regular sleep schedule is an important part of overall health. Prior research
Researchers from the University of Oulu in Finland took a closer look at the relationship between sleep and heart health in a long-term study of middle-aged adults.
They found that people who had both an irregular sleep schedule and got under 8 hours of sleep per night had the highest MACE risk.
The Centers for Disease Control and Prevention (CDC)
Lack of regular sleep can contribute to a number of both physical and mental health issues, including affecting the heart.
Poor sleep affects the body’s circadian rhythm, which helps
With this in mind, the researchers in the current study wanted to learn more about the impact of sleep habits on heart health. They were interested in the participants’ bedtimes, sleep midpoints, wake-up times, and sleep duration.
The scientists used data from 3,231 adults in the Northern Finland Birth Cohort 1966. The participants wore activity monitors on their wrists for up to 2 weeks, and the researchers used the first 7 consecutive nights of sleep data for their analysis.
They grouped sleep characteristics into the following categories:
- regular
- fairly regular
- irregular
The participants also completed health and lifestyle questionnaires that covered smoking and alcohol use. They underwent clinical testing for blood pressure, BMI, cholesterol, and blood sugar.
The researchers used national health records during the 10 following years to track cardiac events such as heart attack, stroke, and cardiovascular-related death.
The researchers found that sleep health may be about more than just the total number of hours slept per night.
They found that participants with irregular bedtimes who also slept for less than 8 hours per night had a higher risk of cardiovascular events, including heart attack and stroke, over the following decade.
These participants had nearly double the MACE risk compared to participants with more consistent sleep schedules.
The researchers also found a similar increase in risk among people with highly irregular sleep midpoints. Sleep midpoint, the halfway point between falling asleep and waking up, is considered an important marker of circadian rhythm stability.
Sarathi Bhattacharyya, MD, a pulmonologist, sleep medicine specialist, and medical director of MemorialCare Sleep Disorders Center at Long Beach Medical Center, who was not involved in the study, spoke with Medical News Today and explained the significance of this finding.
He noted that when circadian rhythm is disrupted, “the body’s period for recovery and hormone signaling gets disrupted…chronic sleep deprivation can increase stress hormones and contribute to adverse cardiovascular risk.”
The researchers did not find that irregular wake-up time alone was associated with increased cardiovascular risk.
The researchers said the findings suggest sleep consistency may be an important public health focus, a point also emphasized by the experts who spoke with MNT.
“A two-fold increase in MACE is a significant difference and reiterates the importance of addressing sleep quality and duration issues in patients who may already have other risk factors for cardiac disease,” shared Bhattacharyya.
Brian Zachariah, MD, a board-certified psychiatrist with Mindpath Health, said the findings are clinically meaningful.
“The hazard ratio of approximately 2.0 is significant considering other traditional cardiovascular risk factors (like smoking vs non-smoking, diabetes vs no diabetes),” shared Zachariah.
What stood out most to Zachariah was that irregular bedtimes, rather than wake-up times, were linked to higher heart risk. He said this may reflect broader behavioral instability and circadian disruption.
“Irregular sleep timing/circadian disruption plays a role in metabolic and inflammatory dysregulation. It can cause insulin resistance, increase systemic inflammation, which in turn can elevate atherosclerosis and thrombosis.”
— Brian Zachariah, MD
Cheng-Han Chen, MD, a board-certified interventional cardiologist and medical director of the Structural Heart Program at MemorialCare Saddleback Medical Center, also shared his thoughts with MNT.
“These findings add to our current understanding of how important sleep quality is to maintain heart health,” said Chen.
Chen also pointed out that disruptions in the circadian rhythm can cause cortisol and adrenaline to fluctuate, which can contribute to higher blood pressure and obesity.
“Heart disease is already the leading cause of death in the United States, and a two-fold increase in cardiovascular risk as noted by this study would be quite a significant and meaningful difference,” shared Chen.
