A growing chorus of voices, including media personalities, is advocating for the permanent adoption of daylight saving time, a movement that gains some traction from recent research indicating brighter daytime light exposure can lead to better sleep.
The study, conducted by researchers at the University of Manchester and published in NPJ Biological Timing and Sleep, analyzed data from 89 adults over 500 days. Participants wore light sensors and sleep trackers while maintaining sleep diaries. The findings suggest a correlation between brighter and more consistent daytime light exposure and earlier sleep onset, earlier wake times, and increased deep sleep during the initial hours of the night.
“Light impacts human sleep through a specific pathway, starting with the eye,” explained Jennifer Martin, Ph.D., a clinical psychologist and professor at Florida International University's Herbert Wertheim College of Medicine, who was not involved in the study. “When light hits specific cells in the retina, it communicates to the brain that it's daytime, meaning we should be alert and active.”
Morning light, in particular, is considered beneficial for regulating the body's internal clock, helping to maintain a consistent sleep-wake cycle. Martin recommends seeking out natural light early in the day to promote healthy sleep routines. Conversely, limiting exposure to bright light in the evening hours can also enhance sleep quality.
"Varying your wake time by more than about one hour can lead to feelings of 'jet lag' and contribute to trouble with regularly sleeping well," Martin added, underscoring the importance of consistent wake-up times.
The push for permanent daylight saving time has been vocalized by figures such as Sean Davis, CEO and co-founder of The Federalist, who has argued for more afternoon sunlight. Comedian Joe Machi has also voiced support, citing safety benefits for children involved in after-school activities.
However, the University of Manchester study acknowledges certain limitations. Researchers noted that the study identified an association between daytime light exposure and sleep patterns but did not definitively establish a causal relationship. Furthermore, light exposure was measured using wrist-worn devices, rather than directly at the eyes, which are the primary interface for light's effect on the internal clock. The study also did not account for other potential influencing factors on sleep, such as physical activity levels or meal timing. Adults are generally advised to aim for at least seven hours of sleep per night, seeking professional help for chronic sleep issues.