Irregular Circadian Rhythms May Increase Heart Disease Risk by 300%, According to a New Study

You’ve probably heard of circadian rhythms but do you know what they are? And do you know how they might affect your health?

Your circadian rhythm is your body’s internal clock. Think of it like the ocean’s tides. There’s a natural rhythm to it all.

Specifically, according to the National Institute of General Medical Sciences, circadian rhythms are the physical, mental and behavioral changes we experience over a 24-hour cycle. Light and dark are the biggest influencers of our circadian rhythms—they influence wake and sleep cycles—but there are other influences as well, including stress, physical activity, food intake, temperature and social environment. 

Our circadian rhythms, in turn, influence functions in our bodies, including sleep patterns, hormones, appetite, digestion and body temperature. And, according to a study published on December 29, 2023, in the Journal of the American Heart Association, our circadian rhythms may significantly influence our health. 

How Was the Study Conducted?

The study included 4,521 male and female adults with an average age of 49 from several different races and ethnicities, including Asian, Black, Hispanic and non-Hispanic White participants. Researchers used data from the 2013-2014 National Health and Nutrition Examination Survey (NHANES). Specifically, they studied the characteristics of the participants in the accelerometry-based physical activity monitoring examination. 

An accelerometer is essentially a fancy pedometer that records more than just steps—it picks up all types of movement. Researchers were looking at 24-hour rest-activity patterns and sleep-wake cycles, as well as circadian influences and how this, in turn, influences health factors and disease, including heart disease, blood pressure, obesity and belly fat. 

What Did the Study Find?

After adjusting for lifestyle and other factors, the researchers found that our circadian rhythms significantly influence our health—in one way or the other. 

Specifically, these researchers found:

• Participants with greater circadian rhythmicity (greater stability with their circadian rhythms) had a 39% to 62% lower risk of heart disease, hypertension (high blood pressure), obesity and central adiposity (unhealthy belly fat). 
• Participants with a more active wake period had 19% to 72% lower risk of heart disease, hypertension, obesity and central adiposity.
• Participants with regular sleep-wake and rest-activity patterns had a 52% lower risk of heart disease and a 23% lower risk of obesity. 
• Participants with irregular circadian rhythms and inefficient sleep increased their chances of heart disease by more than threefold and their risk of obesity by 24%. 
• Participants with later and less restful sleep periods had a 36% to 2 times higher chance of developing heart disease, hypertension, obesity and unhealthy belly fat.

And there’s more. As researchers dug further into the data, they also found a link between greater circadian instability and other health issues, including a 24% increase in diabetes risk, a 31% higher chance of developing metabolic syndrome and an 18% higher risk of dyslipidemia (high cholesterol, high triglycerides). And since these are all risk factors for heart disease, they naturally increase the risk for that, too. 

How Does This Apply to Real Life?

Other studies have shown the link between sleep and heart disease—and how getting enough quality sleep can even help you live longer. 

There’s also evidence that a lack of quality sleep increases inflammation in the body, which in turn negatively affects the immune system and puts you at higher risk for chronic disease, including heart disease, diabetes, arthritis and cancer. 

Previous studies have also shown that too much sitting and a lack of physical activity also predisposes us to disease, including an increased risk of dementia and heart disease. The remedy? Get up and move more throughout the day. 

While this current study takes a slightly different spin from previous studies, it also confirms what previous studies have shown. 

The difference between this study and previous studies is that this one looked specifically at sleep-wake cycles and rest-activity cycles, which make up our circadian clocks. And the message is simple: When we mess around with our natural circadian rhythms, we place ourselves at higher risk for heart disease and its risk factors. 

You can think of circadian rhythms as akin to music. Music has a beat and flows with that rhythm. It’s synchronized. That’s what a stable circadian rhythm is like. But if you were to start throwing in random beats that confuse the natural rhythm and notes that don’t belong there, that’s what an unstable circadian rhythm is like; things start to fall apart. 

How do you remedy an unstable rhythm? You start by establishing habits that bring more stability to your life. 

We know that seven to nine hours of quality sleep is best for most people. Have a regular bedtime routine and healthy sleep habits—and keep them consistent.

If you have a sedentary job, make it a habit to get up and move every 30 minutes or so to break up long periods of sitting. It doesn’t have to be a long break—stand up and stretch, or walk a lap around your home or office. Beyond that, get more regular physical activity throughout the week. 

Stress can also throw a wrench into your circadian rhythm. Incorporate stress management into your day, whether that’s some deep breathing or meditation. And figure out the source of your stress and address it. 

Going long periods without eating also increases stress and throws your rhythm—and energy—off, so be sure to include regular healthy meals and snacks throughout your day. 

The Bottom Line

While some personalities fight against structure and stability, more and more evidence suggests that some level of structure and regularity in our habits and lifestyles is a healthier path. As this study suggests, being more in alignment with our circadian rhythms helps reduce heart disease and its risk factors. And based on previous studies, practicing healthy habits can also increase our happiness, improve mental health and reduce stress.