Screen-Time Before Bed Can Disrupt Sleep, Says Study

Exposure to artificial light can disrupt circadian rhythms and sleep, leading to deleterious consequences on health.

We have all experienced the effect of staring into our phones for hours just before sleep time. Dozing off, which should be one of the most effortless of tasks, is extremely susceptible to screen time. A study by researchers at Salk Institute has now provided an explanation behind this susceptibility.

The study, published in the journal Cell Reports, has shown how certain cells in the eye process ambient light and thereby reset the internal clocks of the body, also known as the circadian rhythm.

Exposing them to artificial light at night can confuse this rhythm and lead to many health issues.

In the words of Salk Professor Satchin Panda, senior author of the study,

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.

Professor Satchin Panda

The sensory membrane behind our eye, called retina, contains tiny light-sensitive cells which are similar to pixels in a camera.

Exposing these cells to ongoing light regenerates a protein called melanopsin, that signals levels of ambient light directly to the brain to instigate consciousness, alertness, and sleep.

Melanopsin plays an important role in regulating our internal clock after 10 minutes of light exposure and, under bright light, curtails the hormone melatonin, responsible for regulating sleep.

“Compared to other light-sensing cells in the eye, melanopsin cells respond as long as the light lasts, or even a few seconds longer,” says Ludovic Mure, co-author of the paper.

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

Ludovic Mure

The results of the study might make possible the discovery of new treatments for sleep related problems like insomnia, jet lag or migraines, which can further lead to chronic issues.