Why ‘Springing Forward’ Isn’t Good for Your Heart

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Ahh, spring is in the air again! The birds are chirping, the flowers are blooming and warmer weather has finally arrived—at least in some parts of the country. However, likely everyone’s least favorite phrase associated with this time of year is: “spring forward!” That’s right, with springtime comes our annual ritual of turning the clocks ahead one hour to savor a bit more sunlight in the evening. But with that “tradeoff,” most people in the U.S. lose an hour of sleep when the clocks move ahead. There are several questions surrounding this phenomenon, including:

  • Why do we change the clock each spring and fall?
  • Should we remain on one time permanently?
  • Does this practice affect our cardiovascular health?

Alternating between standard (November through March) and daylight time (March through October) began during each World War as an attempt to save energy for the war effort. During the 1960s, the federal government regulated the time change. In 2007, Congress reaffirmed this time structure, passing legislation to keep the current time periods used today. Since the daylight time extension, many lawmakers have proposed bills to make daylight time permanent—and 60 to 75% of the American public support abolishing the biannual time change.

However, one of the concerns is that sticking with daylight saving time will affect sleep patterns. Daylight time has been shown to shorten sleep time in high school students post-daylight time transition. If we keep daylight time during the winter, the mismatch between our biological (our body’s natural rhythm) and social (societal norms in a 24-hour period) clocks (called circadian misalignment) will worsen, with average wake-up times ranging from two, three or maybe even four hours before the sun rises, especially at the western edge of time zones.

These changes in our sleep schedule affect our health—especially our cardiovascular health. Heart attack and stroke are more common near the springtime clock change. Short sleep (not getting enough sleep) and circadian misalignment cause an imbalance in our autonomic nervous system, which is important for blood pressure regulation. Our sympathetic nervous system is our fight or flight system, which is active during times of stress and releases more stress hormones throughout the body. Our parasympathetic nervous system is our rest and digest system and helps lower our blood pressure and heart rate.

Short sleep and circadian misalignment are forms of stress that activate the sympathetic nervous system and inhibit the parasympathetic nervous system, which may lead to high blood pressure and high heart rates. Over time, hypertension can contribute to cardiovascular disease progression.

How can we prevent these problems? For now, prepare for the “spring forward” by going to bed earlier for a few days leading up to the time change. This is especially important for people with cardiovascular disease risk factors. While lawmakers push for all-year daylight saving time, sleep experts argue that all-year standard time should be adopted to better align with our biological and social clocks. But no matter what time it is, treat sleep not as a luxury, but as a necessity for a healthy body and mind.

Listen to the #APSSleepSpace Twitter Space to hear Ian M. Greenlund, PhD, and Jason Carter, PhD, discuss this topic with APS Media Relations Specialist Mario Boone.

Ian M. Greenlund, PhD, is a postdoctoral research fellow in the Department of Cardiovascular Medicine at Mayo Clinic in Rochester, Minnesota. His work focuses on sleep enhancement and blood pressure regulation and sleep disorders and hypertension in racially underrepresented populations. Additional interests include autonomic nervous system regulation, neurovascular control of blood pressure and alcohol abuse-mediated cardiovascular disease.

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