A new experiment has revealed how light-sensitive cells in our eyes can mess up our internal clock when exposed to light.
The blue light from our devices could affect our retinal cells which could disrupt our circadian rhythms which is commonly known as the body clock. The findings can help clarify why prolonged exposure to light, especially blue light emitted from our phones, changes a person’s body clock. The study shows that long exposure to screens makes a person’s body out of sync with its natural internal clock or circadian rhythm that disrupts sleep and damages health.
Sustained light exposure late at night is found to be one of the causes of insomnia, jet lag, migraines, and circadian rhythm disorders. The researchers, from the Salk Institute for Biological Studies in La Jolla, CA, expect that their research will lead to advances in the treatment of the said sleep disorders. Scientists have discovered that circadian rhythm disorders are linked to serious health issues. This includes metabolic syndrome, insulin resistance, cancer, obesity, and cognitive dysfunction.
Because of artificial sources of light coming from our phones, our sleep-wake cycles are no longer in sync with the natural patterns of day and night. “This lifestyle,” says senior study author Prof. Satchidananda Panda, “causes disruptions to our circadian rhythms and has deleterious consequences on health.”
Circadian Rhythm and Sleep
A person’s body has a natural internal clock that normally follows a 24-hour day-night pattern. This is medically known as the circadian rhythm or the sleep-wake cycle. The internal clock regulates our feelings of wakefulness and sleepiness. Its mechanisms are complicated, and they follow signals from a certain part of the brain that observes ambient light.
Our cells, tissues, hormones, and organs all rely on this timekeeper. Making sure to get enough sleep and going to sleep at the right time helps to keep it working well. The National Heart, Lung, and Blood Institute (NHLBI) implies that 50–70 million people in the United States alone have ongoing sleep disorders. They also mentioned that 7–19 percent of adults reported not getting enough sleep daily and 40 percent said that they unintentionally fall asleep during the day at least once a month.
Light-Sensitive Cells Affect the Body’s Clock
The study focused on a specific group of cells in the retina. They centered around the light-sensitive membrane that lines the back of the inside of the eye.
These cells are sensitive to light but are not involved in transmitting images to the brain. Rather, they process levels of ambient light to supply signals for biological mechanisms. Melanopsin, a protein that helps cells to process ambient light, regenerates inside the cell with prolonged exposure to light. Continuous regeneration of melanopsin triggers signals to the brain to be alert, conscious, and awake.
If melanopsin regeneration is extended, the lights are bright, it then sends a signal that resets the biological clock. This process blocks melatonin, a hormone that makes you sleepy.