The body craves consistency. When that doesn’t happen — because you’ve stayed up too late scrolling, worked a night shift, eaten a late-night snack, or experienced a surge of stress hormones — it can disrupt your circadian rhythm, the body’s innate 24-hour clock that keeps you on a healthy cycle.
Regular disruptions to your circadian rhythm can increase your risk for heart disease, obesity, type 2 diabetes, and high blood pressure, according to a new scientific statement from the American Heart Association (AHA).
“Substantial evidence has accumulated from a wide range of studies demonstrating the critical role the circadian system plays in human health,” says Kristen Knutson, PhD, a coauthor of the new statement and an associate professor of neurology at Northwestern University’s Feinberg School of Medicine in Chicago.
Here’s what the evidence shows about the link between circadian rhythms, heart health, and metabolism.
The Relationship Between Your Circadian System and Heart Health
Circadian rhythms help regulate heart rate, blood pressure, metabolism, and hormone secretion, including cortisol, which is important for stress response and metabolism, the statement explains.
It defines circadian health as “the optimal function, rhythmical character, and alignment of the circadian system with the light-dark cycle.” The body calibrates its circadian system via light detected by the eye and transmitted to the brain, which sets the rhythm of the body’s internal clock.
The statement outlines several factors that can affect the alignment of your circadian system:
Light Exposure Light helps synchronize your internal clock, so morning exposure to light can reinforce a healthy circadian rhythm. Nighttime artificial light (especially blue light from screens) suppresses the body’s production of the sleep-regulating hormone melatonin and delays sleep. Too much nighttime light exposure is also tied to an increased risk of heart disease.
Meal Timing Eating late at night or having irregular mealtimes disrupts the circadian rhythms of your organs, including the liver and pancreas, which can cause blood sugar spikes or dips and weight gain. Eating earlier in the day (for example, having breakfast before 8 a.m.) is linked to a lower risk of type 2 diabetes and better heart health and weight.
Physical Activity Timing Exercising in the morning or afternoon can keep the biological clock running as it should; evening workouts can throw it off. Exercise timing can also influence blood pressure, blood sugar control, and sleep quality. However, the authors noted that more research is needed to determine the optimal exercise time for different people.
Shift Work, Light Pollution, and Inconsistent Sleep Working nontraditional schedules might expose someone to light pollution, irregular mealtimes, and inconsistent sleep habits compared with people with traditional day-night schedules. This can increase the risk of heart disease.
Individual Internal Clocks Being a night owl or an early bird affects how people respond to light, meals, and exercise. AHA’s statement suggests that tailoring interventions to someone’s natural internal clock could improve circadian alignment, but “assessing true circadian rhythm is challenging.”
Why Good Sleep Matters to Your Heart
“Sleep quality and overall cardiovascular health have been intimately tied together for a long time, and it’s nice that it’s being called out,” says Andrew Freeman, MD, a cardiologist at National Jewish Health in Denver, who wasn’t involved in creating the AHA statement.
Dr. Freeman emphasizes the vital role of sleep and sleep quality to his patients, along with exercising regularly and eating a healthy, mostly plant-based diet, which also impacts sleep.
He says seven to nine hours of uninterrupted sleep has been associated with a decreased risk for heart problems, especially when you can stick to a consistent sleep schedule.
Along with heart problems, circadian rhythm disruptions can also affect your metabolism and digestive tract, hormones, and nervous system.
They may also lead to sleep disorders, including insomnia, sleep apnea, jet lag, and shift work disorder.
Ultimately, the new AHA statement “emphasizes the importance of the circadian system, which is different from sleep itself,” Dr. Knutson says. “We know that there are several components of a healthy lifestyle, including diet, exercise, and sleep. Circadian health emphasizes that the timing of these behaviors is an important characteristic in addition to amount and quality.”
How to Keep Your Circadian Rhythm in Sync
“We all need to think about the consistency of our sleep timing if we seek optimal health,” says Chris Winter, MD, a neurologist and sleep specialist in Charlottesville, Virginia. Dr. Winter was not involved with the AHA statement, but says it represents another scientific body recognizing the importance of sleep to your health.
If your circadian rhythm is out sync, here are some strategies to get it back on track:
Avoid naps, especially in the afternoon or evening.
Create a comfortable sleep environment with your ideal temperature.
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Knutson K et al. Role of Circadian Health in Cardiometabolic Health and Disease Risk: A Scientific Statement From the American Heart Association. Circulation. October 28, 2025.
Tom Gavin joined Everyday Health as copy chief in 2022 after a lengthy stint as a freelance copy editor. He has a bachelor's degree in psychology from College of the Holy Cross.
Prior to working for Everyday Health, he wrote, edited, copy edited, and fact-checked for books, magazines, and digital content covering a range of topics, including women's health, lifestyle, recipes, restaurant reviews, travel, and more. His clients have included Frommer's, Time-Life, and Google, among others.
He lives in Brooklyn, New York, where he likes to spend his time making music, fixing too-old electronics, and having fun with his family and the dog who has taken up residence in their home.
Erica Sweeney has been a journalist for more than two decades. These days, she mostly covers health and wellness as a freelance writer. Her work regularly appears in The New York Times, Men’s Health, HuffPost, Self, and many other publications. She has a master’s degree in journalism from the University of Arkansas at Little Rock, where she previously worked in local media and still lives.
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