Our modern lives—filled with late-night screen time, irregular work hours, and skipped breakfasts—are taking a toll on one of the body’s most important systems: the internal clock.
According to a new scientific statement from the American Heart Association, disruptions to our natural circadian rhythm—the roughly 24-hour cycle that governs sleep, metabolism, and hormone release—can raise the risk of serious health problems, including heart disease, high blood pressure, obesity, and type 2 diabetes.
Published in Circulation, the statement titled “Role of Circadian Health in Cardiometabolic Health and Disease Risk” highlights how vital it is to keep our daily routines in sync with our internal timing.
“Circadian rhythms are much more than just sleep and wake cycles,” said Dr. Kristen Knutson, the lead author and a neurology professor at Northwestern University’s Feinberg School of Medicine.
“They regulate countless biological processes like digestion, body temperature, and hormone release. When these rhythms are disrupted, our health suffers.”
The circadian rhythm is controlled by a small group of brain cells called the suprachiasmatic nucleus, located in the hypothalamus.
These neurons act as a “master clock,” using signals from light that enters through the eyes to coordinate timing throughout the body. Every organ—including the heart, liver, and pancreas—has its own internal clock that depends on cues from the brain to function properly.
When we eat, sleep, and exercise at inconsistent times, this delicate system becomes misaligned, creating stress for the body and increasing disease risk.
Sleep is one of the strongest influences on the circadian rhythm. Research shows that irregular sleep schedules, even when total sleep time is adequate, can disrupt the internal clock.
Many people experience “social jet lag”—the habit of sleeping later on weekends than on weekdays—which has been linked to higher rates of obesity and diabetes.
Keeping a consistent bedtime and wake-up schedule helps the body’s systems stay synchronized and supports heart and metabolic health.
Light exposure is another powerful factor. Natural light in the morning reinforces healthy rhythms, while artificial light at night—especially blue light from phones or computers—can delay sleep and interfere with melatonin, the hormone that promotes rest.
Even dim light exposure at night has been associated with increased cardiovascular risk.
When we eat also matters. Late-night meals or irregular eating patterns can throw off the body’s internal clocks, especially in organs like the liver and pancreas that regulate blood sugar.
Studies suggest that eating earlier in the day, such as having breakfast before 8 a.m., supports better metabolism and lowers the risk of diabetes. Similarly, the timing of physical activity can fine-tune circadian rhythms, with morning or afternoon exercise generally promoting better alignment.
People who work night or rotating shifts face particular challenges, as constant schedule changes, nighttime light exposure, and irregular meals can all disrupt circadian health. This misalignment is now recognized as a key risk factor for cardiovascular disease.
Dr. Knutson emphasizes that everyone’s internal timing is unique. “Some people are naturally early risers, others are night owls,” she said. “Recognizing and respecting your body’s rhythm can make a real difference in your health.”
Future research, she added, may help doctors personalize lifestyle recommendations based on an individual’s internal clock. Wearable technology and artificial intelligence could soon make it easier to measure circadian rhythms in real life, not just in the lab.
“Everyone has an internal clock, and it’s time we started listening to it,” said Dr. Knutson. “Small steps—like keeping a regular sleep schedule, eating meals earlier, and getting morning sunlight—can help protect your heart, balance your metabolism, and support overall well-being.”
If you care about heart health, please read studies that vitamin K helps cut heart disease risk by a third, and a year of exercise reversed worrisome heart failure.
For more health information, please see recent studies about supplements that could help prevent heart disease, stroke, and results showing this food ingredient may strongly increase heart disease death risk.
Source: American Heart Association.
