Colors of sunset and sunrise reset our circadian rhythms

Circadian rhythms are the natural, internal processes that regulate the sleep-wake cycle and repeat roughly every 24 hours.

These rhythms, influenced by environmental cues like light and darkness, play a crucial role in various bodily functions ranging from sleep regulation to hormone release.

When these rhythms fall out of sync – due to factors such as artificial lighting, irregular schedules, or travel across time zones – people can experience disruptions in sleep, mood, and overall well-being.

Lights reset circadian rhythms

New research has revealed that the vibrant blue and orange hues seen at sunrise and sunset may hold the key to resetting these rhythms.

By mimicking these natural light cycles, scientists at the University of Washington in Seattle have developed a novel LED light that emits alternating wavelengths of blue and orange.

The LED device, designed to realign circadian rhythms, has been proven to significantly advance melatonin production. This could offer a promising solution for those suffering from sleep disorders and other health issues linked to circadian misalignment.

Improving circadian health

Published in the Journal of Biological Rhythms, the research represents a breakthrough in how humans can influence circadian rhythms.

The findings hold significant promise for improving circadian health. Study co-author Jay Neitz is a professor of ophthalmology in the UW School of Medicine.

“Our internal clock tells us how our body’s supposed to act during different times of day, but the clock has to be set. If our brain is not synced to the time of day, then it’s not going to work right,” said Professor Neitz.

Disrupted circadian rhythms

The study suggests new strategies to combat seasonal affective disorder (SAD) and other health issues linked to disrupted circadian rhythms, offering hope for improving sleep quality, mood stabilization, and overall mental health.

Circadian rhythms are naturally reset daily by the 24-hour solar light-dark cycles, which help regulate our biological processes in alignment with the environment.

Professor Neitz noted that the light used in the LED device has alternating blue and orange wavelengths which stimulate the circuit that our brains use to reset our internal clocks.

The role of melatonin

Melatonin, the hormone responsible for sleep regulation and the body’s natural sleep-wake cycle, is produced when light signals from the eyes stimulate specific areas of the brain to begin the winding-down process for sleep.

This hormone plays a critical role in helping the body adjust to darkness, promoting relaxation, and ensuring restful sleep.

People spending more time under artificial light, especially in the evening, often experience delayed melatonin production, which can disrupt their sleep patterns and overall well-being.

Prolonged exposure to artificial lighting can also interfere with the body’s ability to properly align with natural day-night cycles, contributing to sleep disturbances and fatigue.

To address this issue, the research team conducted a study comparing different types of artificial lights to measure their impact on melatonin production and their effectiveness in resetting circadian rhythms.

A revolutionary approach to lighting

Unlike other commercial products that emphasize blue light to trigger melanopsin, this new LED light emits alternating blue and orange wavelengths, which stimulate a different circuit in the retina.

“The light we developed does not involve the melanopsin photopigment. It stimulates a blue-yellow opponent circuit that operates through cone photoreceptors in the retina,” explained Professor Neitz.

In an experiment, participants were exposed to three different light devices. The alternating blue-orange LED led to the most significant shift in melatonin production, advancing it by 1 hour and 20 minutes, compared to just 40 minutes for the blue LED and 2.8 minutes for white light.

“Even though our light looks white to the naked eye, we think your brain recognizes the alternating blue and orange wavelengths as the colors in the sky,” said Professor Neitz.

Lighting the way forward

The LED device has now been successfully commercialized through the University of Washington. The product is distributed by TUO, a Chicago-based company. This marks an important step toward bringing this technology to the public.

By harnessing the natural color palette of sunrise and sunset, this innovative lighting solution offers a new approach to resetting circadian rhythms, potentially transforming how we address sleep disorders, mood regulation, and overall health.

The technology holds the promise of improving well-being for those affected by modern lighting and lifestyle challenges, helping individuals reconnect with the rhythms of the natural world.

The study is published in the journal Journal of Biological Rhythms.

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