Earlier this month—November 2 at 2 a.m. to be precise—the ritual of turning clocks back by one hour occurred once again in most of the U.S. This ritual is called Daylight Saving Time (DST). The other part of the ritual happens in March when the DST procedure requires setting the time ahead by one hour. According to Wikipedia, DST is designed to "make better use of the longer daylight available during summer so that darkness falls at a later clock time." Arizona and Hawaii are the only two states that don't implement DST—a decision for which the two states have received much ridicule. The voters and politicians in the two states don't support DST because they are already "high sunshine" states, and feel the switch is disruptive rather than helpful. But ongoing research is demonstrating that the two states were right to stick to their guns for another reason: The yearly DST switch is bad for health. Leading medical organizations, including the American Academy of Sleep Medicine, the Sleep Research Society and the American Medical Association already support making no yearly time changes. According to them, the evidence shows that DST changes disrupt the body's circadian rhythm—a disruption that has negative consequences on numerous aspects of health. The three organizations advocate for the entire country sticking to permanent Standard Time, and say the move would most certainly save lives. The CDC also acknowledges the health risks of the biannual clock change and publishes suggestions to help workers adapt to the time change. Understanding circadian rhythm The circadian rhythm is the body's internal, 24-hour clock. The reason disturbing it is so detrimental is that this "master clock" controls the timing of virtually all biological processes—not just sleep. When the rhythm is disrupted, it creates a misalignment where the body is performing the wrong functions at the wrong time of day. Decades of research on the human circadian rhythm has shown disruption can affect health across different systems including: • Neurological and mental healthDisruption of the circadian rhythm directly impacts the brain's function and chemistry. This can lead to mood disorders, cognitive decline, sleep disorders, gastrointestinal issues, and weight gain and diabetes. • Cardiovascular healthCircadian rhythms are critical for regulating the heart and blood vessels, so disruption increases the risk of cardiovascular events such as heart attack and stroke. Chronic disruption, such as that experienced by late-shift workers, is an independent risk factor for high blood pressure and other cardiovascular diseases. • Immune functionThe internal clock regulates the timing of immune cell activity, and studies show disruptions of this vital regulation handicaps the body's inflammatory response—leading to a compromised immune system. This potentially makes a person more susceptible to infections with an increased risk of autoimmune disorders. New 2025 study A new study conducted at Stanford University used computer modeling to examine just how devastating the known side effects are. The authors of the study noted that their goal was to test a longstanding question: Beyond the short-term spikes in heart attacks after “springing forward,” how do different time policies shape long-term health? The researchers' ultimate conclusions were that ending the DST biannual changes could lower obesity prevalence by 0.78% (about 2.6 million fewer cases nationwide) and reduce strokes by 0.09% (approximately 307,000 cases). It is important to note that these are not direct counts of patients, but are projections from mathematical models that connect light exposure, circadian rhythm and health outcomes. Still, the modeling is based on the well-established negative effects of circadian rhythm disruption. To conduct the study, the researchers modeled light exposure for every county in the continental U.S., then fed the data into established models of human circadian rhythms. The team compared these estimates with county-level health data from the Centers for Disease Control and Prevention. After accounting for age, income, and other health influences, the models predicted links between circadian burden on obesity and stroke rates. As noted earlier, the affects on both were dramatic. The research, published in Proceedings of the National Academy of Sciences in September 2025, is important because it will help further discussion on the wisdom of a yearly DST change. To date the reasoning for DST policies have centered on lifestyle: more evening light for recreation versus brighter mornings for commuting. The new study, however, shifts the discussion toward health effects. The models suggest that ending biannual clock changes could predictably reduce millions of cases of obesity and hundreds of thousands of strokes in the continental United States—clearly a goal worth reaching. - - - Is your circadian rhythm under attack? Fight back with Optimal Sleep Gummies to restore healthy sleep! Click the banner ad to learn more. Sources for this article include: Proceedings of the National Academy of Sciences, CDC.gov, Wikipedia (circadian rhythm).
