Scientists Uncover Why Screen Time Disrupts Sleep


Researchers have discovered how certain cells in the eye process artificial light and reset the body clock.

The discovery could explain how time spent looking at a screen disrupts sleep patterns.

Cells in the retina

The Salk Institute for Biological Studies in California in the US carried out research on mice and how cells in the eyes respond to light.

The researchers focused on the retina in the back of the eye. The retina contains tiny cells that are light-sensitive. When these cells are exposed to light, a protein called melanopsin regenerates within them.

Continual regeneration of melanopsin triggers signals to the brain to tell it about light conditions. The brain uses this information to regulate sleep.

Exposure to light

In this study, the researchers turned on the production of melanopsin in retinal cells in mice. They found that some of these cells are able to sustain light responses, but others lose sensitivity.

Further investigations found that proteins called arrestins help keep the melanopsin sensitive when exposed to light.

It was found that the mice needed to have two types of arrestin to help them make melanopsin.

Artificial light

This research uncovers the mechanisms behind how cells being exposed to artificial light confuses the internal body clock, and the ability to regulate sleep.

Professor Satchin Panda, author of the study, said: “We are continuously exposed to artificial light, whether from screen time, spending the day indoors or staying awake late at night. This lifestyle causes disruptions to our circadian rhythms and has deleterious consequences on health.”

Circadian rhythm

The body’s internal clock follows a sleep-wake cycle, known as the circadian rhythm. This regulates how awake or tired we feel. As we are exposed to more and more artificial light, especially when using devices with screens late at night, our circadian rhythms are no longer linked to day and night.

Circadian rhythm disorders are linked to health problems such as insulin resistance and cognitive dysfunction. Previous studies have also found that having a disrupted circadian rhythm could lead to depression.

New treatments

It is hoped that this discovery could lead to new targets that could counter the impact of artificial light, for example by finding ways to influence melanopsin to reset the internal clock. This could lead to new treatments for insomnia, jet lag and migraines.


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