Sleep
Blue Light Has an Apocalyptic Impact on Sleep and Human Health
Prolonged exposure to high-energy blue light upsets the circadian rhythm.
Posted August 26, 2021 Reviewed by Vanessa Lancaster
Key points
- Exposure to high-energy blue light upsets circadian rhythm and can lead to the development of insomnia and other sleep disturbances.
- Blue light exposure may suppress melatonin, increase alertness, and interfere with sleep in both people and animals.
- Even a single speck of LED blue light shining from some electronic component in the corner of the room at night will contribute to poor sleep.

The light shines in the darkness, and the darkness can never extinguish it (John 1:5).
This statement from the Bible may have presaged what some experts call the “Blue Light Apocalypse.” The blue-spectrum light now glowing 24/7 from energy-efficient, light-emitting diodes (LEDs), brightening homes, businesses, cities, and the screens of literally billions of electronic devices–3.8 billion smartphone users in the world, according to 2021 estimates–is turning us into sleep-deprived zombies. And, like an apocalypse, the impact on human health could prove universally disastrous.
Just last year (2020), The Lancet carried an article indicating that prolonged exposure to high-energy blue light upsets circadian rhythm, and this interference leads to the development of insomnia and other sleep disturbances. Authors of a 2018 article in the World Journal of Biological Psychiatry say their study results indicate “blue light exposure may suppress melatonin, increase alertness, and interfere with sleep” in both people and animals. Not surprising then that as many as 30 percent of adults in the United States reportedly experience some form of “sleep dysregulation,” according to the article, as they check email, text, or watch a movie on LED-lit screens right up until the time they climb into bed.
Of course, sleep deprivation can put a person in a constant state of stress, cause mood disorders and lead to various physical and mental disturbances, including anxiety and depression. Estimates place the number of people in the United States with some form of anxiety as high as 25 percent. Meanwhile, an August 2021 article on the Psychiatric Times website discussed the relationship between blue light, depression, and bipolar disorder. Other experts blame LED light pollution for the onset of actual physical disease–everything from obesity and diabetes to breast and prostate cancers (2018 report from the Barcelona Institute for Global Health).
Compounding the problem is the ongoing replacement of incandescent bulbs, considered a safer source of light for human health, with the more environmentally-friendly LEDs. A 2017 University of Michigan study, for example, recommended immediate replacement of incandescent and halogen lighting with blue-emitting fluorescent lamps and LEDs. A year later (2018), California passed a law banning the use and sale of incandescent lighting as part of the state’s new energy-efficiency standards.
Retina Uses Light to Talk to Brain
Researchers in Japan found that people who slept in total darkness were at far less risk of developing depression than those with some type of light glowing – even as low of brightness as what emanates from a night light. One might ask, “How can that be? The eyes are closed in sleep.”
Indeed, they are, but science is learning much more about the retina, which is composed of brain tissue and functions as part of the central nervous system. The retina uses light to communicate with the brain–even through closed eyelids–and affects basic physiological systems like circadian rhythm and melatonin production. Even the single speck of LED blue light shining from some electronic component in the corner of the room at night will prompt non-image-forming retinal cells to send electrical signals to the brain and establish a neuronal chatter that interferes with the brain’s work of solidifying memories and eliminating metabolic waste during sleep.
One neuro-optometrist reports getting a less-than-satisfying night of sleep while at home on vacation until she placed a book in front of a tiny LED light emanating from a device in her bedroom. Her action is supported by a 2017 study, published in the Journal of Psychiatric Research, in which authors note that “exposure to blue-wavelength light in particular from [electronic devices] may affect sleep by suppressing melatonin and causing neurophysiologic arousal.”
What is so important about melatonin?
Melatonin is a natural hormone that sets the circadian clocks internal to our cells and organs. It aligns our day-and-night rhythm and greatly affects the sleep cycle. Writing in a 2018 edition of the Journal of Psychiatric Research, scientists report that colleagues and health experts have become increasingly aware of “how nocturnal light exposure contributes to poor sleep…Melatonin acts as the hormonal signal for the onset of the biological night,” and environmental light can delay that signal. “A delay in melatonin onset, therefore, may be expected…a factor contributing to subsequent delays in sleep initiation mechanisms,” these study authors state.
Artificial light, in general, is polluting the night among societies throughout the globe. Experts say that even the low glow of city street lamps filtering through bedroom windows has an untold effect on sleep and overall health. However, the greatest concern is reserved for the LEDs that appear to be the most disruptive of the circadian rhythm.
Scientists from the University of Haifa and the Assuta Sleep Clinic reported in 2017 that exposure to “short-wavelength blue light” dramatically reduced continuity of sleep and obstructed the body’s natural process of reducing its temperature during sleep.
‘My World Is Blue’
The shift to LEDs and the unmitigated expansion of blue-light-emitting electronic devices have brought to reality the Love Is Blue song lyrics of the 1960s: “Blue, blue, my world is blue.” Yet, it does not have to be so–at least not all night. The temptation to remain connected by text, email, and social media sites must be tempered by a few preventive steps to protect our health, our sleep, and our sanity:
- Keep the night light on (you do not want to stumble going to the bathroom in the middle of the night) but switch to a device that utilizes red light. Red light is less likely to affect your melatonin level and circadian rhythm.
- Put the screen on your mobile phone and other devices that require charging while you sleep on night mode. Night mode cuts the harsher blue backlight in favor of a warmer tone.
- Block out that diode glow coming from a nearby electronic component. It may be just a spot of light, but it can hurt you.
- Pull the television out of the bedroom. One of the worst things you can do is fall asleep with the television light flickering for half the night.
- Your body’s melatonin production begins in the evening. So, do yourself a favor. Finish the emailing and texting and shut down your laptop or mobile phone at least two hours before bedtime. Crazy idea, but you might even pick up a book, read, and relax in that last hour before falling asleep.
- Turn off any unnecessary outdoor lighting around your house and invest in some good blinds or shades to enhance the darkness in your bedroom.
Despite its environmental benefits, blue light has become an international threat to human health. It represents a potential apocalypse, creating a world of electronic-driven, sleep-deprived “walking dead.”
Blue, blue, my world is blue, indeed. Turn off the lights and go to sleep.