A new study published in PNAS suggests that ending the biannual clock changes and adopting permanent standard time could improve public health by stabilizing circadian rhythms and reducing risks such as stroke and obesity.

Modeling based on light exposure, circadian impact, and health data indicates that most people would experience the least circadian burden under permanent standard time, especially in terms of sleep health and overall well-being.

The research highlights that the human circadian cycle is approximately 24 hours and 12 minutes, with light exposure at different times influencing this cycle—morning light speeds it up, while evening light slows it down.

However, the study has limitations, including assumptions about consistent light habits and the exclusion of factors like weather, geography, and behavior, which could affect real-world outcomes.

The authors acknowledge these limitations and emphasize that light exposure is not the sole factor affecting health, suggesting that other environmental and social factors also play a role.

Supporters call for more evidence-based research on time policies, recognizing the ongoing debate and the likelihood of future changes to daylight saving practices.

While findings favor permanent standard time for health benefits, the authors note that factors like weather, geography, and social behavior must be considered, and natural daylight during winter cannot be changed by policy.

The study underscores that time policies only shift clock settings and do not alter the actual daylight hours, which are determined by Earth's orbit and rotation.

Long-term health benefits from consistent time policies require further real-world research, especially considering past public backlash against permanent daylight saving time.

Although the health outcome improvements are small, even minor reductions in disease cases highlight the importance of considering circadian health in policy decisions.

The study also notes that irregular light habits and indoor lifestyles may diminish the benefits of policy changes, emphasizing that Earth's position and sunlight are the fundamental factors affecting light exposure.

Supporters of permanent daylight saving time cite benefits like energy savings, crime reduction, and more leisure, but face public opposition over concerns such as children going to school in the dark.

Major health organizations endorse year-round standard time, citing health benefits, although this stance is based on theory rather than extensive data.