• Adults in midlife and older age who tend to be most active in the evening, especially women, showed poorer overall heart health than those without a strong preference for mornings or evenings, based on the American Heart Association’s Life’s Essential 8 measure.
• Analysis of UK Biobank data suggests that common habits among night owls, including lower-quality diets, too little sleep, and higher rates of smoking, help explain why their cardiovascular health scores were lower.
• Researchers say the findings point to a clear opportunity, since improving daily habits such as sleep, diet, and smoking cessation could help night owls reduce their risk of heart attack and stroke.

Late-Night Activity Tied to Poorer Heart Health

Adults in middle age and later life who tend to be more active in the evening were found to have worse cardiovascular health than those who are active earlier in the day. The association appeared to be stronger among women, according to new research published today in the Journal of the American Heart Association, an open-access, peer-reviewed journal of the American Heart Association.

The findings suggest that when people are most active during the day may play an important role in long-term heart health.

Study Tracks Sleep Timing in More Than 300,000 Adults

Researchers examined health data from more than 300,000 adults (average age of about 57 years) enrolled in the UK Biobank. The analysis focused on chronotypes, which describe a person’s natural preference for sleep and wake timing, and how those preferences relate to cardiovascular health.

Participants were grouped based on their self-identified daily patterns. About 8% described themselves as “definitely evening people,” meaning they typically went to bed very late (for example 2 a.m.) and reached peak activity later in the day. Around 24% reported being “definitely morning people,” who tended to wake up earlier, go to bed earlier (for example 9 p.m.), and be most active earlier in the day. The remaining 67% were categorized as having an “intermediate” chronotype if they were unsure or said they were neither clearly a morning nor evening person.

Cardiovascular health was evaluated using the American Heart Association’s Life’s Essential 8™ metrics. This framework looks at behaviors and health factors known to support heart health, including eating a healthy diet, staying physically active, not smoking, and getting good-quality sleep. It also includes maintaining healthy levels of body weight, cholesterol, blood sugar, and blood pressure.

Key Differences Between Night Owls and Early Birds

The researchers identified several notable patterns when comparing chronotype groups:

Compared with people in the intermediate category, those classified as “evening people,” often called night owls, were 79% more likely to have an overall poor cardiovascular health score.

Night owls also had a 16% higher risk of experiencing a heart attack or stroke during a median follow-up period of about 14 years.

The link between evening chronotype and lower heart health scores was stronger among women than among men.

Much of the increased heart disease risk seen in evening types was linked to lifestyle habits, particularly nicotine use and insufficient sleep.

In contrast, “morning people,” also known as early birds, showed a 5% lower prevalence of poor cardiovascular health scores compared with individuals without a strong morning or evening preference.

Why Evening Types May Face Added Risk

“‘Evening people’ often experience circadian misalignment, meaning their internal body clock may not match the natural day-to-night light cycle or their typical daily schedules,” said lead study author Sina Kianersi, Ph.D., D.V.M.; a research fellow in the division of sleep and circadian disorders at Brigham and Women’s Hospital and Harvard Medical School, both in Boston. “Evening people may be more likely to have behaviors that can affect cardiovascular health, such as poorer diet quality, smoking and inadequate or irregular sleep.”

This misalignment may make it harder for night owls to maintain habits that support long-term heart health.

Lifestyle Changes Could Reduce Risk

The findings are not entirely discouraging for people who prefer late nights, according to Kristen Knutson, Ph.D., FAHA, volunteer chair of the 2025 American Heart Association statement, Role of Circadian Health in Cardiometabolic Health and Disease Risk. Knutson was not involved in the study.

“These findings show that the higher heart disease risks among evening types are partly due to modifiable behaviors such as smoking and sleep. Therefore, evening types have options to improve their cardiovascular health,” she said. “Evening types aren’t inherently less healthy, but they face challenges that make it particularly important for them to maintain a healthy lifestyle.”

Tailoring Treatment to Body Clocks

The American Heart Association scientific statement led by Knutson also recommends taking chronotype into account when planning treatment or lifestyle interventions.

“Some medications or therapies work best when they align with a specific time of relevant circadian rhythms, and this time will vary depending on whether you are a morning, intermediate, or evening chronotype,” she said. “Targeted programs for people who naturally stay up late could help them improve their lifestyle behaviors and reduce their risk of cardiovascular disease.”

Study Limitations

The researchers noted that most UK Biobank participants were white people and generally healthier than the overall population, which may limit how broadly the findings apply to other groups. In addition, chronotype was assessed only once and was based on self-reported information rather than repeated measurements.

The study was partially funded by the American Heart Association.

• Men reached a 5% risk of cardiovascular disease roughly seven years earlier than women, revealing a clear and early gap in heart health.
• Coronary heart disease accounted for most of this difference, driving the earlier rise in risk among men.
• Heart disease risk looked similar for men and women until about age 35, when men’s risk began to increase more quickly.
• The earlier onset in men cannot be explained by smoking, high blood pressure, or diabetes alone, pointing to additional biological or social influences.

Heart Disease Risk Appears Earlier in Men

Men start developing coronary heart disease years before women do, and the difference can be seen as early as the mid-30s, according to a large, long-term study led by Northwestern Medicine. Coronary heart disease is a major cause of heart attacks.

Based on more than 30 years of follow-up, the findings suggest that heart disease screening and prevention may need to begin earlier in adulthood, especially for men.

“That timing may seem early, but heart disease develops over decades, with early markers detectable in young adulthood,” said study senior author Alexa Freedman, assistant professor of preventive medicine at Northwestern University Feinberg School of Medicine.

“Screening at an earlier age can help identify risk factors sooner, enabling preventive strategies that reduce long-term risk.”

Why the Male Female Gap Has Not Closed

Previous research has long shown that men tend to develop heart disease earlier than women. Over time, however, common risk factors such as smoking, high blood pressure and diabetes have become more alike between the sexes. Because of this, researchers expected the difference in heart disease timing to shrink.

Instead, the gap remained. That result was unexpected, Freedman said.

To better explain why these differences continue, Freedman and her colleagues say researchers need to look beyond standard measures like cholesterol and blood pressure and consider a wider range of biological and social influences.

The study was published on January 28 in the Journal of The American Heart Association.

Tracking Heart Disease From Young Adulthood

The research team analyzed data from the Coronary Artery Risk Development in Young Adults (CARDIA) study. The project enrolled more than 5,100 Black and white adults between ages 18 and 30 in the mid-1980s and followed them through 2020.

Because participants were healthy at the start, the researchers were able to identify when cardiovascular disease risk first began to separate between men and women. Men reached a 5% rate of cardiovascular disease, defined broadly to include heart attack, stroke and heart failure, about seven years earlier than women (50.5 versus 57.5 years).

Most of this difference was due to coronary heart disease. Men reached a 2% incidence of coronary heart disease more than 10 years earlier than women. Stroke rates were similar for both sexes, and differences in heart failure appeared later in life. “This was still a relatively young sample — everyone was under 65 at last follow-up — and stroke and heart failure tend to develop later in life,” Freedman explained.

Traditional Risk Factors Do Not Tell the Whole Story

The researchers examined whether common risk factors could explain why men developed heart disease sooner. These included blood pressure, cholesterol, blood sugar, smoking, diet, physical activity and body weight.

While some factors, especially high blood pressure, accounted for part of the difference, overall cardiovascular health did not fully explain the earlier onset in men. This points to the influence of additional biological or social factors.

Age 35 Emerges as a Key Turning Point

One of the most notable findings was when the risk gap began. Men and women had similar cardiovascular risk through their early 30s. Around age 35, men’s risk increased more quickly and remained higher through midlife.

Many heart disease prevention and screening efforts focus on adults older than 40. The new results suggest this approach may miss an important early window for action.

The authors point to the American Heart Association’s PREVENT risk equations, which can predict heart disease starting at age 30, as a promising tool for earlier intervention.

Gaps in Preventive Care for Young Men

Closing the gap between men and women may be difficult because preventive care use is uneven among U.S. adults ages 18 to 44. Women are more than four times as likely as men to attend routine checkups, largely because of gynecologic and obstetric visits.

“Our findings suggest that encouraging preventive care visits among young men could be an important opportunity to improve heart health and lower cardiovascular disease risk,” Freedman said.

She also stressed that cardiovascular disease remains the leading cause of death for both men and women, making prevention essential for everyone.

The study is titled “Sex Differences in Age of Onset of Premature Cardiovascular Disease and Subtypes: The Coronary Artery Risk Development in Young Adults Study.” Freedman is supported by the National Heart, Lung, and Blood Institute (K01HL165038). CARDIA is conducted and supported by the National Heart, Lung, and Blood Institute in collaboration with the University of Alabama at Birmingham (75N92023D00002 & 75N92023D00005), Northwestern University (75N92023D00004), University of Minnesota (75N92023D00006) and Kaiser Foundation Research Institute (75N92023D00003).

The work was led by Chunlei Guo, a professor of optics and physics and a senior scientist at URochester’s Laboratory for Laser Energetics. Guo and his colleagues detailed the new method in a study published in Advanced Functional Materials. Their approach focuses on modifying the inside surface of aluminum tubes by etching it to create microscopic and nanoscale pits. This textured surface becomes superhydrophobic, allowing it to strongly repel water and remain dry.

How Trapped Air Prevents Sinking

When a treated tube is placed in water, its water-repelling interior captures a stable pocket of air inside. This trapped air keeps water from filling the tube, which prevents it from becoming heavy and sinking. The process resembles natural strategies seen in diving bell spiders, which carry air bubbles underwater, and in fire ants, which form floating rafts using their water-resistant bodies.

“Importantly, we added a divider to the middle of the tube so that even if you push it vertically into the water, the bubble of air remains trapped inside and the tube retains its floating ability,” says Guo.

Improved Stability in Rough Conditions

Guo’s research group first demonstrated superhydrophobic floating devices in 2019. That earlier design relied on two water-repelling disks sealed together to create buoyancy. While effective, the disks could lose their ability to float when tilted at extreme angles. The newer tube-based design simplifies the structure and offers much greater stability, especially in turbulent environments similar to ocean conditions.

“We tested them in some really rough environments for weeks at a time and found no degradation to their buoyancy,” says Guo. “You can poke big holes in them, and we showed that even if you severely damage the tubes with as many holes as you can punch, they still float.”

From Floating Rafts to Renewable Energy

The researchers showed that multiple tubes can be connected to form rafts, which could serve as the foundation for ships, buoys, or floating platforms. In laboratory tests, the team experimented with tubes of different lengths, reaching nearly half a meter. Guo says the design can be scaled up to sizes large enough to support heavy loads.

Beyond transportation and infrastructure, the team also demonstrated that rafts made from superhydrophobic tubes could capture energy from moving water. This capability suggests a potential role for the technology in generating electricity from waves, adding a renewable energy application to its list of possibilities.

This project was supported by the National Science Foundation, the Bill and Melinda Gates Foundation, and URochester’s Goergen Institute for Data Science and Artificial Intelligence.