A person lies in bed, awake, at 5:30 a.m. and appears to not have gone to bed yet.
Staying up until the wee hours of the morning can create a sleep habit that adversely affects your health. (For Spectrum Health Beat)

People with irregular sleep patterns may be at increased risk for heart attack and stroke, a new study suggests.

Researchers analyzed data from nearly 2,000 Americans between 45 and 84 years of age who did not have heart disease.

Participants wore a wrist device that monitored their sleep for seven days, including bedtime, sleep duration and wake time.

They were then followed for an average of nearly five years. During that time, 111 participants had a heart attack, stroke or other heart event.

Those whose sleep varied two hours or more a night were twice as likely to have heart events as those whose sleep varied by fewer than 60 minutes.

Over one year, eight of every 1,000 people with the most consistent sleep patterns had a heart event, compared with 20 in 1,000 of those with the most irregular sleep, according to the study published in a recent issue of The Journal of the American College of Cardiology.

“When we talk about interventions to prevent heart attacks and stroke, we focus on diet and exercise,” said lead author Tianyi Huang, an associate epidemiologist in the Division of Network Medicine at Brigham and Women’s Hospital in Boston.

“Even when we talk about sleep, we tend to focus on duration—how many hours a person sleeps each night—but not on sleep irregularity and the impact of going to bed at different times or sleeping different amounts from night to night,” he noted in a hospital news release.

This study suggests that healthy sleep isn’t just about quantity but about consistency and that it can have an important effect on heart health, Huang said. However, it only shows an association, rather than a cause-and-effect link.

“In the future,” Huang said, “we’d like to explore whether changing one’s sleep patterns by going to bed consistently each night may reduce a person’s risk of future cardiovascular events.”