The Effects of Blue Light From Sunup to Sundown

by | Feb 8, 2021


The Effects of Blue Light From Sunup to Sundown

Like or not, we are surrounded by blue light day and night, inside and outside. The blue light from our screens is a more common topic of conversation as we navigate the digital-first world, but we are also exposed to blue light naturally from the sun. While we know that blue light from artificial sources at night is harmful to our health—linked to blindness, obesity, cancer and more—by understanding the effects of blue light, you can also use it to your advantage during the daytime.

Sources of Blue Light

The sun produces plenty of visible light, but blue light specifically has a high-energy wavelength. This natural source of blue light keeps us alert and awake, regulating our circadian rhythm. However, most people spend the majority of their time indoors, so they are exposed at length to artificial sources of blue light. Computers, televisions, LED lamps, tablets, smartphones, digital alarm clocks, smart watches and even that Peloton screen all create blue light. We come up against blue light powered devices at school, home and work — week in and week out. 

Blue Light During the Day

Here’s the good news. During the day, you can take advantage of the effects of natural blue light. According to a study in Environmental Health Perspectives, blue light can improve your alertness, reaction times and attention span. In addition to helping you stay awake, the same study found that blue light can increase your hormone secretion, heart rate, body temperature and gene expression. This means you can use blue light to keep your body alert and functioning better during the day.

However, that doesn’t mean you should turn to your screens for an energy boost. The source of the blue light matters, and a moderate dose from the sun is different from the direct, close range exposure from our screens. While the American Academy of Ophthalmology explains that digital devices produce a lot less blue light than sunlight — and many claim it’s not cause for concern — when you consider that we’re staring directly at our devices for extended periods of time, it becomes a cause for concern.

There’s no question whatsoever that in laboratory studies, in cell cultures and in animal models, this close and prolonged exposure to our screens damages retina cells. When working or studying during the day, adding blue-blocking screen protectors on all of your devices can help protect your eyes. Reticare is a fantastic, affordable brand with extensive science to back-up the effects of their products. (Use code DRKARA for a 10% discount).

Blue Light During the Night

Further, blue light at night can make it harder for you to fall asleep and can cause you to wake up too early. This happens because blue light waves disrupt your circadian rhythm, which is how your body regulates its sleep-wake cycle. Blue light also suppresses the melatonin hormone that your body needs to fall asleep.

Research suggests that when you do not get enough sleep at night because blue light is keeping you awake, you are at a higher risk of developing several chronic conditions such as depression, obesity, cancer and diabetes. Not getting enough sleep every night also has a strong negative effect on mood.

Fortunately, since the blue light we’re exposed to at night comes from digital devices, we can control and decrease our screen time at night to protect our bodies. Turn off your phones, computers or tablets before going to bed. Avoid screen time at least two hours before bed time. Avoid sleeping with the television on and make sure your digital alarm clocks are not emitting blue light. And perhaps most importantly, if you are using your devices in the evening, wear true blue light-blocking glasses. To be effective at protecting your circadian rhythm, the lenses should be deep yellow, as not all blue light glasses are effective. If you can see the color blue through the glasses, they are not blocking the blue light.  Less yellow glasses or turning the night mode on your screen will help to some degree, but it’s very hard to quantify since it’s not a complete reduction.  A few companies have developed scientific algorithms to show that their yellow glasses will protect your circadian rhythm and are actually classified as a medical device.  One such company is and although they are expensive, they are reliable and will give you the peace of mind that you are actually protecting yourself while still allowing some preservation of the blue color spectrum.

Bottom line: Blue light comes from many sources, natural and artificial. During the day, you can use the sun’s natural blue light waves to boost your performance and alertness. During the night, it’s quite the contrary. It’s important to control blue light exposure by limiting the use of digital devices before bedtime or wearing blue blocking glasses that are deep yellow in color so you can rest and sleep better, avoiding chronic health conditions caused by a lack of regular, quality REM sleep.



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