How does Blue Light Affect Us?

Blue light seems to be the talk of the town lately. With artificial lights, big-screened televisions, and our many smart devices, we are exposed to blue light constantly throughout the day. Contrary to what you may know, blue light isn’t all bad! We actually get most of our blue light exposure from the sun. The sun emits different levels of blue light throughout the day and helps us regulate our internal clock. Blue light emissions peak midday, keeping us energized, alert, and focused. It tapers off in the evenings, helping us to feel more relaxed and sleepy come nightfall. The harmful effects of blue light come when we introduce artificial lights into our routines, affecting our natural body rhythms and mood, as well as the health of our eyes and skin.

Effects Circadian Rhythm
Blue light in the evenings can throw off our body’s natural sleep cycle. Our circadian rhythm is the internal clock in our brain that is responsible for regulating cycles of alertness and sleepiness. It regulates by responding to environmental lighting cues specifically from the sun. More blue light is given off by the sun during the daytime than in the evenings. This is supposed to help us feel more awake during the day and more sleepy come nightfall. This cycle also helps to regulate hormone secretion, cellular function, and gene expression. It is so important that evidence shows that disrupting our natural rhythm can lead to certain cancers, metabolic dysfunction, and mood disorders.

Researchers have found that light exposure suppresses melatonin production. Melatonin is a hormone that influences our circadian rhythm. Studies indicate that a two-hour exposure to blue light in the evening suppresses melatonin production. (1) Any kind of light, even if it is a dim bedside table lamp, can suppress melatonin production. However, blue light, like from a smartphone or LED light, suppresses melatonin production more powerfully. According to Harvard researchers, blue light suppressed melatonin for about twice as long as green light and even shifted circadian rhythms by twice as much; Green light shifted circadian rhythms by 1.5 hours, whereas blue light shifted them by 3 hours. (2) This is one of the many reasons we love our Himalayan Salt Lamps. The impurities in the salt filter out blue light and emit a calming, red-orange hue that won’t alter your circadian rhythm. This is also a good night light alternative for kiddos who prefer a light at night (although dark rooms are best).

Effects Mood
It comes as no surprise that blue light can affect our mood. Have you ever felt groggy or irritated after a “brain break”? As nice as it can be to sit back and relax for a minute on our phones, it may be causing far more harm than good. According to the APA, sleep disruption is one way to identify major mood disorders such as depression, bipolar disorder, post-traumatic stress disorder, and anxiety. Many of these sleep disturbances are reported to be paired with irregular light cycles. Many of these sleep disruptions are also caused by light exposure in the evenings. (3)

Can Trigger Headaches and Migraines
Researchers have conducted plenty of studies supporting the claim that blue light can trigger and exacerbate headaches and migraines. It has been suggested that blue light has this effect because of a specific neural pathway from the eyes to the brain. (4)(5)(6) We have three light-identifying pathways; rods, cones, and intrinsically photosensitive retinal ganglion cells (ipRGCs). The ipRGCs are the photoreceptors responsible for setting our circadian rhythm. These cells are also the most sensitive to blue light and can ultimately worsen headache pain and other symptoms by increasing the perception of pain, creating throbbing sensations, and speeding up the spreading pain of a headache. (3)

Can Cause Eye Strain
Staring at digital screens as much as we do is rough on our eyes. Many of us work with a computer during the day, and then come home and relax on our devices at night. That is a lot of artificial light exposure! Our screens cause our eyes to absorb a lot of unfocused light which can cause issues with focusing, squinting, and eye fatigue. Researchers also speculate that blue light specifically can damage our eyes because human eyes aren’t as good at blocking blue light as they are at blocking UV light. This means that most of the visible blue light passes through the eye and to the retinas, which can, with time, damage the retinas, cause vision changes, and put you at a higher risk of macular degeneration. (7)

Effects Skin Health
Did you know that your smartphone, tablet, or computer could be causing premature aging? During the day, our skin is exposed to light and is focused on protection. But, theoretically, in the evenings, the skin is supposed to be focused on repairing the damage that occurred that day and preparing for the next morning. But with artificial lights and devices, we disrupt our circadian rhythm and severely decrease the amount of time our bodies get to repair skin damage. This can cause an increase in reactive oxygen species (ROS) production, DNA damage, and inflammatory mediators. (8) Researchers have concluded that even short term exposures to blue light can cause an increase in reactive oxygen species (ROS) generation. (9)(10)(11) When skin cells were exposed to blue light from common consumer electronic devices, (in this case, iPhones and iPads were used) ROS increased significantly (up to 93%). (11) The link between oxidative stress and aging is well documented. Overproduction of ROS can lead to damage to macromolecules like lipids, DNA, and proteins. Damage to these macromolecules can accelerate signs of aging and lead to inflammation, hyperpigmentation, and the breakdown of collagen and elastin. (12)

So how should we protect ourselves from blue light?
There are many ways to keep yourself safe from the effects of blue light. 

• If you must use night lights, use dim red lights, as red light is less likely to shift circadian rhythm and suppress melatonin
• Avoid looking at screens beginning 2-3 hours before bed
• Get outside and experience bright, natural light during the daytime! Open your blinds and use bright, natural lighting in your home throughout the day to boost your ability to sleep at night
• Change your light bulbs to warmer tones and colors
• If you must use screens in the evenings, consider using blue light glasses​

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Sources

1. https://pubmed.ncbi.nlm.nih.gov/30311830/
2. https://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side
3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5299389/
4. https://pubmed.ncbi.nlm.nih.gov/27190022/
5. https://pubmed.ncbi.nlm.nih.gov/10759921/
6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2795133/
7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5854379/
8. https://pubmed.ncbi.nlm.nih.gov/31418890/
9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6280109/
10. https://pubmed.ncbi.nlm.nih.gov/29399830/
11. https://pubmed.ncbi.nlm.nih.gov/28315451/
12. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5927356