What is blue light? The effect blue light has on your sleep and more.
Although it is environmentally friendly, blue light can affect your sleep and potentially cause disease. Until the advent of artificial lighting, the sun was the major source of lighting, and people spent their evenings in (relative) darkness. Now, in much of the world, evenings are illuminated, and we take our easy access to all those lumens pretty much for granted.
But we may be paying a price for basking in all that light. At night, light throws the body's biological clock—the circadian rhythm—out of whack. Sleep suffers. Worse, research shows that itmaycontribute to the causation of cancer, diabetes, heart disease, and obesity.
What is blue light?
Not all colors of light have the same effect. Blue wavelengths—which are beneficial during daylight hours because they boost attention, reaction times, and mood—seem to be the most disruptive at night. And the proliferation of electronics with screens, as well as energy-efficient lighting, is increasing our exposure to blue wavelengths, especially after sundown.
Light and sleep
Everyone has slightly different circadian rhythms, but the average length is 24 and one-quarter hours. The circadian rhythm of people who stay up late is slightly longer, while the rhythms of earlier birds fall short of 24 hours. Dr. Charles Czeisler of Harvard Medical School showed, in 1981, that daylight keeps a person's internal clock aligned with the environment.
Is nighttime light exposure bad?
Some studies suggest a link between exposure to light at night, such as working the night shift, to diabetes, heart disease, and obesity. That's not proof that nighttime light exposure causes these conditions; nor is it clear why it could be bad for us.
A Harvard study shed a little bit of light on the possible connection to diabetes and possibly obesity. The researchers put 10 people on a schedule that gradually shifted the timing of their circadian rhythms. Their blood sugar levels increased, throwing them into a prediabetic state, and levels of leptin, a hormone that leaves people feeling full after a meal, went down.
Exposure to light suppresses the secretion of melatonin, a hormone that influences circadian rhythms. Even dim light can interfere with a person's circadian rhythm and melatonin secretion. A mere eight lux—a level of brightness exceeded by most table lamps and about twice that of a night light—has an effect, notes Stephen Lockley, a Harvard sleep researcher. Light at night is part of the reason so many people don't getenough sleep, says Lockley, and researchers have linked short sleep to increased risk for depression, as well as diabetes and cardiovascular problems.
Effects of blue light and sleep
While light of any kind can suppress the secretion of melatonin, blue light at night does so more powerfully. Harvard researchers and their colleagues conducted an experiment comparing the effects of 6.5 hours of exposure to blue light to exposure to green light of comparable brightness. The blue light suppressed melatonin for about twice as long as the green light and shifted circadian rhythms by twice as much (3 hours vs. 1.5 hours).
In another study of blue light, researchers at the University of Toronto compared the melatonin levels of people exposed to bright indoor light who were wearing blue-light–blocking goggles to people exposed to regular dim light without wearing goggles. The fact that the levels of the hormone were about the same in the two groups strengthens the hypothesis that blue light is a potent suppressor of melatonin. It also suggests that shift workers and night owls could perhaps protect themselves if they wore eyewear that blocks blue light. Inexpensive sunglasses with orange-tinted lenses block blue light, but they also block other colors, so they're not suitable for use indoors at night. Glasses that block out only blue light can cost up to $80.
LED blue light exposure
If blue light does have adverse health effects, then environmental concerns, and the quest for energy-efficient lighting, could be at odds with personal health. Those curlicue compact fluorescent lightbulbs and LED lights are much more energy-efficient than the old-fashioned incandescent lightbulbs we grew up with. But they also tend to produce more blue light.
The physics of fluorescent lights can't be changed, but coatings inside the bulbs can be so they produce a warmer, less blue light. LED lights are more efficient than fluorescent lights, but they also produce a fair amount of light in the blue spectrum. Richard Hansler, a light researcher at John Carroll University in Cleveland, notes that ordinary incandescent lights also produce some blue light, although less than most fluorescent lightbulbs.
Protect yourself from blue light at night
- Use dim red lights for night lights. Red light is less likely to shift circadian rhythm and suppress melatonin.
- Avoid looking at bright screens beginning two to three hours before bed.
- If you work a night shift or use a lot of electronic devices at night, consider wearing blue-blocking glasses or installing an app that filters the blue/green wavelength at night.
- Expose yourself to lots of bright light during the day, which will boost your ability to sleep at night, as well as your mood and alertness during daylight.
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FAQs
Constant exposure to blue light over time could damage retinal cells and cause vision problems such as age-related macular degeneration. It can also contribute to cataracts, eye cancer and growths on the clear covering over the white part of the eye.
What do doctors say about blue light? ›
Dr. Thaker says we should be much more concerned about blue light coming from the sun than from electronic devices. “Overexposure to sunlight can cause eye disease, but the small amount of light from digital devices has not been shown to cause harm,” Dr. Thaker says.
Is it OK to sleep with a blue night light? ›
Despite being a calm-inducing color on most occasions, blue is not suitable for lighting a bedroom. In fact it's quite the opposite: blue lights throw the sleep cycle off and decreases the production of melatonin.
Is blue light bad for your eyes at night? ›
Too much exposure to blue light late at night (through smart phones, tablets, and computers) can disturb the wake and sleep cycle, leading to problems sleeping and daytime tiredness. Not enough exposure to sunlight in children could affect the growth and development of the eyes and vision.
Are blue light glasses bad for your eyes? ›
The short answer is no, blue light glasses will not damage or hurt your eyes. In fact, they are built to do the opposite. The real problem is the excess blue light we receive from our screens, which has been scientifically proven to cause digital eye strain, disruption to sleep cycles, and mental fatigue.
Why is blue light bad for mental health? ›
Continuous exposure to blue light can increase the cortisol levels in our body as we previously said, so if we also add that we are receiving blue light also at nighttime it completely alters the circadian rhythm, maintaining an alert state even at night, favoring insomnia, increasing and altering the production of ...
Are blue light glasses a gimmick? ›
The Short Answer. The short answer to whether blue light glasses work is – maybe, if you get a good pair. If you're simply looking to block blue light and don't suffer from migraine attacks or hyper light sensitivity, then a good quality pair of blue light glasses may be of some help.
Who should not use blue light therapy? ›
Blue light therapy is not suitable for people with porphyria, a rare blood disorder that causes increased sensitivity to light. Similarly, individuals should not undergo this treatment if they have lupus or an allergy to porphyrins.
How damaging is blue light to your skin? ›
Blue Light and Your Skin
Research shows blue light from electronic devices can lead to changes in your skin cells, including cell shrinkage and death. These speed up the aging process. Even exposures as short as 60 minutes can trigger these changes. Too much blue light could also lead to pigmentation.
Do TV screens emit blue light? ›
The largest source of blue light is sunlight, but is also emitted by laptops and computer monitors, smartphones, tablets, TV, fluorescent and CFL bulbs.
The best color for bedroom sleep typically includes shades that are calming and soothing. Blue has serene and tranquil qualities, closely followed by soft greens and earthy tones like beige. These colors tend to lower stress and create a peaceful environment, making it easier to fall and stay asleep.
Do phones emit blue light? ›
The sun also gives off blue light, helping us feel awake, energized, and ready to take on the day's activities. However, digital devices such as smartphones, TVs, and computer screens also emit blue light, which can impact our ability to fall asleep. Dr.
Do night driving glasses block blue light? ›
Night driving glasses uses yellow-tinted lenses to reduce glare, similar to shooting or hunting glasses. Tinted lenses are popular for sports. Yellow or orange-tinted lenses are particularly popular as the tint helps filter blue light and improves contrast in low-lighting conditions.
Does blue light damage the retina? ›
However, inappropriate lighting exposure (especially from artificial sources of blue light in the evening or at night) may lead to harmful effects on health [2]. Due to its high energy, blue light can cause and accelerate photochemical reactions and retinal cell damage [3].
What does blue light do to your teeth? ›
Blue light itself cannot whiten the teeth. Instead, blue light is used to activate a chemical reaction. You'll apply a specialized whitening gel to the patient's teeth containing either carbamide peroxide or hydrogen peroxide. The blue light activates the compounds in the gel and helps break it apart faster.
How does blue light negatively affect the brain? ›
Others have pinpointed the exact wavelength to be in and around 480nm; it is exposure to this blue light that leads to high discomfort, a greater perception of pain and throbbing and even enhanced spreading of headache pain across the brain.
Can you feel sick from blue light? ›
This is why fluorescent and LED lights, computer and smartphone screens, and sunlight consistently make the list of top triggers for light-sensitive persons. Even for healthy individuals, short-wavelength blue light led to motion sickness and more severe nausea, especially with repeated exposure.
What does blue light do to your face? ›
Blue light therapy can also treat other types of skin disorders. It can be used to improve skin texture and reduce sebaceous hyperplasia, or enlarged oil glands. It can help with removing sun spots, acne, and even scars that were originally caused by acne.
What skin damage is caused by blue light? ›
Too much blue light could also lead to pigmentation. One study linked blue light exposure to more swelling, redness, and pigment changes in people with darker skin. The sun is the biggest source of blue light. Although it can negatively impact your skin when used in certain ways, blue light also has healing properties.
