Our circadian rhythms, or internal clocks, help our bodies regulate many of their important functions, including our sleep-wake cycles. Circadian rhythms are based on a series of physiological and external factors, sunlight being one of them.

During a time change, we don’t only shift the clocks, we also disturb the body’s natural rhythm. This can affect our duration and quality of sleep, immune health, and our cardiovascular system at large. While the fall time change does affect heart health, it doesn’t have nearly as detrimental an impact as Daylight Saving Time in spring.

Daylight Saving Time can contribute to a wide range of issues that can contribute to worsened heart health, including increases in:

• Risk of heart attack
• Risk of cardiovascular disease
• Blood pressure
• Heart rate
• Cortisol levels
• Risk of diabetes
• Risk of arrhythmias

All of these factors also leave us more susceptible to an increased risk of cardiovascular disease. Let’s dive a little deeper:

One of the most dangerous impacts daylight savings has on our bodies is how significantly it increases risk of heart attack. A New England Journal of Medicine study showed that there’s up to a 24% increase in risk of heart attack on the Monday after the spring time change.₁ (A rather startling stat.) This study looked at the data from a Swedish national heart attack registry and discovered that the rate of heart attacks was considerably higher in the days following the time change compared to other times of the year.

While the reason behind this jump in heart attacks is still in the process of being better understood, one speculation is based on the disruption of our circadian rhythms. Because the circadian rhythms is connected to hormones and other physiological functions, when the rhythm is disturbed, it can result in increased blood pressure, heart rate, and cortisol (the stress hormone) levels. All of which increase the risk of heart attack.

Another possibility, likely working in conjunction with the disruption of circadian rhythm, is the disturbance of the autonomic nervous system. This system is in charge of regulating heart rate and blood pressure. So, when the system is out of balance, so are these functions.₂

On top of a heightened risk of heart attacks, another study from the Journal of Clinical Endocrinology and Metabolism found that the time change can contribute to a dysregulation of glucose metabolism, increasing risk of diabetes and other metabolic conditions.₃ Both of which can result in a greater risk of cardiovascular disease.

Of course, the most obvious impact that the time change has is on our sleeping patterns. In fact, it’s been shown that many people experience a decrease in sleep duration and an increase in sleep disturbances soon after the spring time change.₄ These disturbances in sleep can result in higher heart rate, blood pressure, and risk of arrhythmias (or abnormal heart rate patterns).

While these changes impact everyone, certain parts of the population are impacted more than others. Those who are at a greater risk of being affected include older adults as well as those who have pre-existing cardiovascular conditions.₅

There are always steps you can take to keep your heart safe, including during the spring time change. The American Heart Association offers these recommendations:₅

• Getting ample rest before and after the time change
• Slowly adjusting your sleep schedule in the days leading up to the time change
• Maintaining a heart healthy diet
• Keeping up with your regular exercise routines
• Managing stress

We also recommend using the many tools Cardiogram offers to help protect your heart during Daylight Saving Time.