The debate over daylight saving time (DST) has resurfaced as lawmakers consider making it permanent. While the idea of not changing clocks twice a year is appealing to many, sleep experts warn that permanent DST could have significant health implications. The U.S. House passed the Sunshine Protection Act on July 14, 2026, aiming to establish permanent DST, but the Senate has yet to vote on the bill.
Sleep experts agree that eliminating the biannual clock changes is beneficial, but they advocate for permanent standard time instead. The current system of switching between standard time and DST disrupts the body’s circadian rhythms which regulate essential functions like metabolism, hormone levels, and sleep patterns.
The role of light in regulating circadian rhythms
Our bodies rely on light to maintain internal clocks, known as circadian rhythms. Morning light, with its shorter wavelengths, is crucial for resetting these rhythms. It enhances mood and alertness, while evening light, with longer wavelengths, promotes relaxation. Disrupting this natural light pattern can lead to sleep disturbances and other health issues.
The current system of switching between standard time and DST aims to provide bright mornings in winter and sunny evenings in summer. However, sleep experts argue that this disruption can have negative consequences. Studies have shown increased risks of heart attacks, strokes, traffic accidents, and workplace injuries in the days following the time change, particularly in the spring when people lose an hour of sleep.
Why permanent standard time is better for health
Experts argue that permanent standard time aligns better with the body’s natural rhythms. Bright morning light helps regulate sleep patterns, making it easier to fall asleep at night. In contrast, permanent DST would result in darker mornings and brighter evenings, which could disrupt the body’s internal clock and lead to long-term health issues.
For instance, in winter, many Americans would not experience sunrises until after 8 a.m. under permanent DST. This lack of morning light can leave the body without the necessary signals to start its daytime routine, potentially leading to sleep deprivation and other health problems.
The impact of social jet lag
The concept of social jet lag refers to the misalignment between the body’s internal clock and the social clock, or the time on the wall. Daylight saving time exacerbates this misalignment by shifting the social clock an hour ahead of the sun. Morning light is the strongest natural cue for resetting the body’s internal clock, and darker mornings make it harder to stay aligned with the social clock.
Research has linked social jet lag to various health conditions, including shorter sleep duration, type 2 diabetes, metabolic disease, obesity, and cardiovascular disease. While the individual risk is small, the collective impact on a population level can be significant. For example, a 2019 study found that people living farther west within the same time zone, who experience later sunrises and sunsets, had shorter sleep duration and a higher prevalence of health problems.
Permanent standard time, on the other hand, aligns better with the body’s natural rhythms and promotes As the debate continues, it is essential to consider the scientific evidence and prioritize health and well-being.
