BYLINE: Mario Boone

Rockville, Md. (June 16, 2022)—There is broad consensus among physiologists and sleep experts that the U.S. should abandon the biannual one-hour clock change because of its potentially harmful effects on cardiovascular health. Yet, debate is intensifying among experts and in Congress around whether to permanently switch to daylight saving time (i.e., “spring forward”), where time is set one hour later than standard time.    

While the biannual standard and daylight saving time changes are both linked to acute circadian disruption, standard time is associated with an acute increase of sleep, according to Jason Carter, PhD, a cardiovascular and sleep expert and a member of the American Physiological Society. He recently co-authored a new Perspectives article about the topic in the American Journal of Physiology-Heart and Circulatory Physiology.

Daylight saving time is typically associated with acute sleep loss, increased traffic crashes and suicide. One study also found a possible connection between daylight saving time and increased rates of heart attack. Both the spring and fall time changes have been associated with increased rates of stroke. These cardiovascular risks are due to a “misalignment” of the circadian rhythm.

Carter is urging the U.S. House of Representatives to permanently adopt standard time rather than daylight saving time recently passed in the U.S. Senate because it is less harmful to cardiovascular health. Experts say standard time would mean more sleep, synchronization of the internal body clock and more natural light exposure in the morning, among other benefits.

“Although there is building scientific consensus that abolishing the biannual time change has several sleep and circadian health benefits, the preponderance of evidence is opposite to the current legislation and instead suggests a permanent switch to standard time may offer the maximum health and safety benefits. This scientific evidence should be considered as the United States House of Representatives considers the Sunshine Protection Act,” the study authors wrote. 

Carter is vice president for research, economic development and graduate education at Montana State University. He has spent years investigating how sleep impacts cardiovascular health, specifically blood pressure and the nervous system.

Physiology is a broad area of scientific inquiry that focuses on how molecules, cells, tissues and organs function in health and disease. The American Physiological Society connects a global, multidisciplinary community of more than 10,000 biomedical scientists and educators as part of its mission to advance scientific discovery, understand life and improve health. The Society drives collaboration and spotlights scientific discoveries through its 16 scholarly journals and programming that support researchers and educators in their