Our bodies run on a natural 24-hour cycle called the circadian rhythm, which tells us when to sleep, eat, and be active. But today’s busy lifestyles often disrupt this rhythm.
A new scientific statement from the American Heart Association warns that these disruptions can seriously affect our health. Published in the journal Circulation, the statement explains how upsetting our internal clocks could raise the risk of heart disease, type 2 diabetes, obesity, and high blood pressure.
Dr. Kristen Knutson, a sleep and circadian health expert at Northwestern University, led the statement writing group. She says our body clocks control many important functions such as heart rate, blood pressure, digestion, hormone release, and body temperature.
These processes work best when we follow a regular daily schedule that matches the natural light and dark cycle of the day.
When we eat, sleep, and move in ways that don’t match our internal clock—such as staying up too late, sleeping in on weekends, or eating at night—our bodies can become misaligned. This is known as circadian disruption. Over time, it can lead to poor health, especially problems related to the heart and metabolism.
One of the main points of the statement is that sleep timing matters as much as sleep length.
People who go to bed and wake up at different times on weekdays and weekends (a pattern known as “social jet lag”) are more likely to gain weight and develop diabetes. Keeping a regular sleep schedule helps your body clock stay in sync and supports good health.
Light is another powerful influence on our internal clock. Natural sunlight in the morning helps reset the brain’s clock each day, while too much artificial light at night—especially from screens—can throw it off.
Even small amounts of light at night may increase the risk of heart disease. That’s why getting natural light in the morning and reducing screen time at night is recommended.
Meal timing also plays a big role. Eating late at night can confuse the internal clocks in our organs, such as the liver and pancreas, and affect how the body handles blood sugar. Studies show that people who eat earlier in the day, especially before 8:00 a.m., tend to have better blood sugar control and lower risk of type 2 diabetes.
Exercise can help too. Being active in the morning or afternoon may help keep your body clock on track. Late-night workouts, however, may delay your sleep cycle. While more research is needed, the time of day you exercise might influence your blood pressure, sleep quality, and blood sugar levels.
The people most affected by circadian disruption are those who work night or rotating shifts. These workers are often exposed to artificial light at night and have irregular eating and sleeping habits, all of which can increase the risk of heart disease.
Everyone has a different body clock, or chronotype—some people are “morning people,” others are “night owls.” Experts say it’s best to match healthy habits like eating, sleeping, and exercising to your natural rhythm whenever possible. But right now, it’s hard for doctors to measure circadian rhythms in everyday healthcare.
In the future, wearable devices and new technologies may make it easier to track body clock patterns. This could help doctors create personalized health plans based on a person’s unique rhythm.
Dr. Knutson encourages everyone to pay attention to their internal clock. Simple habits like getting morning sunlight, eating meals earlier, and keeping a regular sleep schedule can make a big difference in heart and metabolic health.
More research is needed, but these early findings show that living in sync with your body clock may be a key to staying healthy.
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