Daylight Saving Time: How it Impacts Your Heart & How to Protect Yourself

Cardiogram Crew Heart Health, Sleep

Each year, on the second Sunday of March, we “spring forward,” setting our clocks one hour ahead. This marks the beginning of Daylight Saving Time. While this means longer days with more opportunity for sunshine to look forward to, this time change can also have a negative impact on our hearts.
Why does the spring time change impact our hearts?

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.

How does Daylight Saving Time affect the cardiovascular system?

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:

Increased Risk of Heart Attack

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.

Disturbances of Autonomic Nervous System
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
Dysregulated Glucose Metabolism
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.
Disturbed Sleep Patterns
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).
Who's at greatest risk of being negatively impacted by the time change?
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
How can I protect my heart during the spring time change?

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

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

Using Cardiogram for the Time Change
Here are some of our favorite tools you can use to keep your heart safe during the time change:

Tag your sleep

Be sure your sleep is being tagged and see just how much the time change impacts your particular heart.

Enroll in a habit

All of our heart healthy habits can help to protect your heart during the time change, or anytime. Of course, always be sure to talk to your doctor before making any big lifestyle changes.

SET UP Heart rate alerts

Be sure you’ve activated your heart rate alerts so you know if your heart has gone above or below its safe threshold.

Share data with your doctor

Download PDFs of your data to bring to your next doctor's visit. Keeping track of your sleep and heart rate can help you and your doctor determine how much you're impacted by the time change, and if any further preventative action should be taken in the future.
While the spring time change can work against our hearts, by taking preventative measures and making sure our hearts are being well taken care of, we can help our hearts adjust to the changes.


Cardiogram app shown on phone and smart watch


Cardiogram app shown on phone and smart watch

  1. Janszky I, Ljung R. Shifts to and from Daylight Saving Time and Incidence of Myocardial Infarction. The New England Journal of Medicine. 2008; 359(18): 1966-1968. doi: 10.1056/NEJMc0807104
  2. Kantermann T, Juda M, Merrow M, Roenneberg T. The Human Circadian Clock's Seasonal Adjustment Is Disrupted by Daylight Saving Time. Current Biology. 2007; 17(22): 1996-2000. doi: 10.1016/j.cub.2007.10.025
  3. Reutrakul S, Siwasaranond N, Nimitphong H, Saetung S, Chirakalwasan N, Ongphiphadhanakul B, et al. Effects of an Acute Sleep Deprivation on Glucose Metabolism in Subjects with Normal Glucose Tolerance. Journal of Clinical Endocrinology & Metabolism. 2013; 98(6): E1071-E1077. doi: 10.1210/jc.2012-4133
  4. Kantermann T, Duboutay F, Haubruge D, Hampton S, Darling A, Berry JL, et al. The Acute and Chronic Effects of "Spring Forward" and "Fall Back" Time Changes on Human Sleep and Cardiovascular Function. Sleep Medicine. 2017; 40: 169-177. doi: 10.1016/j.sleep.2017.10.007
  5. American Heart Association. Spring Forward With These Heart-Healthy Tips. 2019. Accessed March 6, 2023.