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CNN reports that Americans spent up to seven hours and 22 minutes on screens each day in 2019— not including screens used for school work.  That was before the pandemic, which pushed people’s social lives onto Zoom video chats.  There are risks in all that screen time.  One common concern is the blue light that emanates from digital devices.

All visible light falls on a color spectrum based on the wavelength frequency and energy levels each color produces.  Blue light is a short wavelength, high-energy, visible (HEV) light.  Darker colors, like blue, are the closest to more dangerous UV wavelengths and strength.  Lighter colors, like red, are on the opposite end of the spectrum, with longer wavelengths and lower energy levels.

Blue light can be harmful.

Blue light can be harmful, like too much salt in our diet.  Our bodies are naturally adept at absorbing and dealing with blue light exposure, but too much can be harmful.

We are surrounded by blue light in our natural environment our whole life.  We tend to only worry about blue light coming from display screens.  It also comes from:

• Naturally, from the sun,
• Fluorescent lights, and
• LED light bulbs.

Most computer monitors, cell phone screens, and flat-screen TVs are additional sources of blue light.  HP explains this is because white light LEDs combine with blue LEDs to create a solid-state light that uses significantly less energy and power than alternative light sources, making it ideal for electronic devices.  It These digital devices cause excess blue light exposure, and there are concerns.

Our skin doesn’t have much of a problem dealing with blue light, but our eyes don’t have the same level of adaptation.  Because the wavelength of blue light is short and powerful, it can penetrate past the cornea to reach the retina, which is the most light-sensitive part of your eye.

Digital eye strain

One of the most common side effects of blue light exposure is digital eye strain, also known as computer vision syndrome.  It is caused by staring at a computer screen for too long and may lead to dry, sore, red eyes and blurred vision.  HP warns that with prolonged exposure, blue light can harm your eyes and lead to macular degeneration.

You can take some easy steps to avoid permanent damage to your eyesight.  Here are several suggestions to control your blue light exposure.  Our bodies are naturally conditioned and programmed to fall asleep when it gets dark and wake up when exposed to light.  Harvard Medical School found that it is essential to limit your screen time because blue light suppresses melatonin for about twice as long as green light and shifts circadian rhythms by twice as much.

The same Harvard study found that green light may be as hard on your eyes as blue light.  The researchers warn that the two lights are similar in strength, and there are few remedies for green light exposure.  Limiting screen time—even if you use a blue light filter is important. 

It’s not just blue light that can affect your vision.  As we age, the lens inside our eye can lose flexibility, resulting in the inability to change focus from far to near.  Regular comprehensive eye exams are important to maintaining eye health, no matter how much time you spend in front of screens.

If you already have prescription glasses, move to multi-focal lenses and have your optometrist add a blue light filter.  If not, “cheaters” from the drugstore may be enough—for a while. 

Blinking

Blinking is our body’s natural defense.  It lubricates and cleans our eyes.  Typically, we blink 10 to 20 times per minute.  However, studies have shown that our blink rate drops when we concentrate.  We only blink 3 to 8 times per minute when reading, watching TV, or looking at a computer screen.  Dry eyes are irritated eyes. 

Take time to rest your eyes every 20 minutes.  Look away from the computer and focus on something distant—like out a window.

1. Close your eyes gently,
2. Squeeze and hold them shut for a moment,
3. Open and relax them.

Remember to blink more often in between, and when you are thinking, instead of squinting at the screen, turn away and blink a few times. 

A blue light filter can be a physical barrier or an application that blocks out blue light.  Physical blue light filters block short, high-frequency waves and allow long, low-frequency ones.  HP says physical blue light screen filters are the easiest and best way to reduce your blue light exposure.  Some are just a clear piece of plastic material that covers your monitor. 

Blue light filtering glasses

Wearing blue light-filtering glasses for 3 to 4 hours before bedtime is the easiest way to keep your melatonin levels in check and your retinas protected.  An inexpensive over-the-counter pair online can cost $10.00 and up to $80.00.  The original Blue Blockers cost $19.95 back in the day.

Many prescription and over-the-counter cheaters have blue light filters in the lenses.  However, if you regularly wear prescription glasses, investing in a physical blue light filter may be a waste of money.

Windows 10

You can also reduce your blue light exposure by adding an app to many of your digital devices.  Microsoft (MSFT) Windows 10 has a built-in Night Light feature to control blue light.  To use Windows 10’s app:

1. Click the Start button,
2. Go to Settings,
3. System,
4. Display,
5. Toggle the Night light switch to turn the feature on.
6. Click the link for Night light settings where you can:

• • Set a schedule that controls the lighting on your computer screen,
  • Setting the screen temperature allows you to adjust the levels of blue light reduction.  Warmer colors filter out more blue light—experiment with settings to see what works best for you.

Apple

If you are an Apple (AAPL) Mac user, Apple’s built-in blue light filter app Night Shift requires macOS Sierra 10.12.4 and specific systems.  If you can, follow these steps to enable Night Shift:

1. Choose the Apple menu,
2. System Preferences,
3. then click Displays,
4. Click the Night Shift tab.

On your Apple iPhone or iPad, go to

1. Settings,
2. Display & Brightness,
3. Tap the Night Shift setting. 

As with all things Google (GOOG) Android, the availability of a built-in blue light filter depends on your specific device and version of Android.  To see if this feature is on your Android device, go to:

1. Settings,
2. Display,
3. Look for an option for a Night Light or Blue Light filter. 

If your Android does not have a blue light filter, consider using Grayscale mode, an accessibility setting for most smartphones.

F.lux is a popular third-party blue light filter application with apps for Windows, Apple, Linux, and Phillips Hue lighting system apps. 

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