Scientists have uncovered how artificial light from smartphones and computers can disrupt sleep, a finding which may lead to new treatments for migraines, insomnia, jet lag and circadian rhythm disorders.

Researchers at the Salk Institute in the US found that certain cells in the eye process ambient light and reset our internal clocks, which is the daily cycle of physiological processes known as the circadian rhythm.

Disrupted rhythm

When these cells are exposed to artificial light late into the night, our internal clocks can get confused, resulting in a host of health issues. The results, published in the journal Cell Reports, may lead to new treatments for migraines, insomnia, jet lag and circadian rhythm disorders.

These disorders have been tied to cognitive dysfunction, cancer, obesity, insulin resistance, metabolic syndrome and more, said researchers.

“We are continuously exposed to artificial light, whether from screen time, spending the day indoors or staying awake late at night,” said Professor Satchin Panda, Salk Institute.

“This lifestyle causes disruptions to our circadian rhythms and has deleterious consequences on health,” said Panda. The back of our eyes contain a sensory membrane called the retina, whose innermost layer contains a tiny subpopulation of light-sensitive cells that operate like pixels in a digital camera.

When these cells are exposed to the ongoing light, a protein called melanopsin continually regenerates within them, signalling levels of ambient light directly to the brain to regulate consciousness, sleep and alertness.

“That’s critical, because our circadian clocks are designed to respond only to prolonged illumination,” he said.

Researchers used molecular tools to turn on production of melanopsin in retinal cells in mice. They discovered that some of these cells have the ability to sustain light responses when exposed to repeated long pulses of light, while others become desensitised.

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