The practice of changing clocks twice a year to adjust for daylight saving time is met with widespread dissatisfaction. A recent survey indicates that only 12% of Americans are content with the current semiannual time shifts.
In response to this sentiment, Congress is considering legislation to eliminate these changes. On July 14th, the U.S. House of Representatives passed the Sunshine Protection Act, a bill that would establish permanent daylight saving time nationwide. This would result in darker mornings and extended daylight hours through the winter. The bill’s passage through the Senate is still pending.
While the elimination of clock changes garners significant support, the public remains divided on whether permanent daylight saving time or permanent standard time would be preferable.
However, health and sleep experts largely agree that the clock changes should cease. Organizations such as the American Medical Association, the American Academy of Sleep Medicine, and the National Sleep Foundation advocate for ending the semiannual shifts. Crucially, these expert bodies recommend permanent standard time, in contrast to the approach proposed by Congress, citing its benefits for public health.
The shift to permanent daylight saving time, with its darker mornings and brighter evenings during winter months, could negatively impact the body’s internal clock, disrupt sleep patterns, and have detrimental long-term health consequences.
The Sun’s Role in Regulating the Body’s Internal Clock
Humans, much like other living organisms, possess internal biological clocks known as circadian rhythms. These rhythms dictate various bodily functions throughout a 24-hour cycle. For instance, the body releases cortisol, a stress hormone, to promote wakefulness in the morning. As evening approaches, melatonin production increases, signaling the body to prepare for sleep. Hormonal fluctuations also occur to stimulate appetite before anticipated mealtimes and to suppress appetite during sleep.
Beyond hormones, scientific research demonstrates that other physiological processes, including blood pressure, metabolism, body temperature, digestion, and immune system function, all follow daily patterns influenced by our internal clocks.
The most significant external cue for these internal clocks is light. Dr. Anita Shelgikar, a neurology professor at the University of Michigan, emphasizes the importance of maintaining the alignment between our internal clocks and external environmental cues.
Morning light, characterized by its shorter blue-green wavelengths, plays a crucial role in synchronizing circadian rhythms. According to Dr. Phyllis C. Zee, a sleep medicine specialist at Northwestern University, morning light enhances mood and alertness. Conversely, light in the late afternoon and evening, with its longer orange-red wavelengths, is more conducive to relaxation and less activating.
While we cannot alter the natural cycle of sunlight, which varies with seasons and geographical location, we can influence how well our artificial timekeeping aligns with these natural light patterns.
The Impact of Semiannual Clock Changes on Circadian Rhythms
The current system of alternating between standard time and daylight saving time was codified in the U.S. in 1966, aiming to maximize daylight during waking hours throughout the year. Standard time is observed from early November to mid-March, followed by daylight saving time for the remainder of the year.
However, sleep experts caution that this practice comes at a cost. Some research suggests an increase in heart attacks, strokes, traffic accidents, workplace injuries, and other cardiovascular events in the days following the time change. While other studies have found no significant effects, the negative impacts appear to be most pronounced in the spring, when the loss of an hour of sleep can be particularly disruptive.
Jamie Zeitzer, a professor and co-director of the Center for Sleep and Circadian Sciences at Stanford University, notes that while the individual risk is small, the cumulative effect on millions of people simultaneously can be significant. Eliminating the clock changes would necessitate a choice between darker winter mornings or less daylight during summer evenings.
Why Permanent Standard Time is Recommended for Health
Sleep experts contend that adhering to permanent standard time offers the most effective way to synchronize the body’s internal clock with natural light patterns. Our bodies are biologically programmed to awaken with morning light and to experience darkness in the evening to facilitate sleep.
Dr. Beth Malow, a neurologist and sleep researcher at Vanderbilt University, explains that bright morning light actually aids in promoting sleep at night. This occurs by resetting our internal clocks, preparing us for sleep when the appropriate time arrives.
Under a permanent daylight saving time system, many individuals would experience sunrise well after 8 a.m. during winter months. Waking in darkness deprives the body of the essential light signal needed to initiate its daytime functions. Conversely, prolonged daylight in the evenings can suppress melatonin production, making it harder to fall asleep at bedtime.
These disruptions to our circadian rhythms can lead to imbalances in hormones, appetite regulation, and mood. Over the long term, they may contribute to chronic sleep deprivation, which is linked to a range of adverse health outcomes, including dementia, heart disease, type 2 diabetes, and certain types of cancer.
Research indicates that within a single time zone, individuals residing in western regions, experiencing later sunrises and sunsets, tend to sleep less and report poorer health compared to those in eastern regions of the same time zone. Several U.S. states and territories, including Hawaii and Arizona, already observe year-round standard time.
The Appeal of Daylight Saving Time Despite Health Concerns
The desire for permanent daylight saving time often stems from factors beyond health considerations. Industries such as retail, outdoor recreation, and tourism benefit from extended daylight hours during warmer months. Furthermore, many cultural traditions and personal memories are associated with long summer days.
Despite these perceived advantages, scientific evidence consistently points towards the health benefits of aligning with natural light cycles. Dr. Shelgikar expresses a hope for a future where health and cherished activities are not mutually exclusive, suggesting that improved sleep and rest could enhance the enjoyment of life’s pleasures.
Historically, the U.S. has experimented with permanent daylight saving time, but the initiative was short-lived, with Congress rescinding the policy within months due to public backlash.