Identifying blue light blocking glasses: 8 easy at-home tests

Blue light blocking glasses have gained immense popularity, with hundreds of brands to choose from. But how can you determine if your glasses truly block blue light? Fortunately, you don’t need to be an eye specialist to find out—there are several at-home tests to assess the quality of your lenses. Here, we’ve gathered a few tests to help you determine whether your glasses really block blue light. If you want to know how, keep reading!

The light reflected from the lenses will reveal the colors being blocked. Hold your lenses in front of a light source and observe the colors reflected from the lenses. If you see blue, it means your glasses block blue light to some degree.

• This test works for clear lenses worn during the day and for glasses designed for computer use.
• This is the simplest test you can perform at home, but it doesn’t reveal how much blue light is being blocked (ideally, it should block at least 30%).

The blue of the sky viewed through clear blue light blocking lenses will appear slightly yellowish. Clear lenses with a yellow tint won’t be noticeable when worn. To check if your lenses have a yellowish tint, step outside and hold the lenses up to a clear, sunny sky. If the sky appears warmer or yellowish through the lenses, your glasses may be blocking at least some blue light.

If your glasses block blue light, the white of the lenses will shift to a slightly yellow hue. For this test, all you need is a white background (like a computer screen or a piece of paper). Hold the lenses above the white surface and look through them to check for any yellowish tint.

• The white background will appear a bit warmer due to special pigments in the lenses that absorb the passing blue light.
• If neither the lenses nor the white background become warmer, it means the glasses only have a simple anti-glare coating, filtering around 5-20% of blue light.

The 'night mode' screen resembles looking through orange-tinted lenses. Many devices with 'night mode' are designed to block blue light on the screen. First, observe the display on your phone or computer in 'night mode' without wearing glasses. Then, turn off night mode and put on your glasses to view the screen. Depending on the intensity of night mode, you'll notice that the image takes on a warmer or yellow-orange tone, similar to wearing orange lenses.

• On Apple devices, this setting is called 'Night Shift.' On Android, it's referred to as a blue light filter.
• Night mode essentially works similarly to blue light blocking glasses, though not every device has this software.
• There are several free blue light blocking software options available for computers and other devices without built-in night mode.

The blue color will turn black when viewed through dark orange or red lenses. Darker night lenses can block most (if not all) blue light. You can search for the 'black and blue square test' online to find an image of a black square next to a blue square. Put on your glasses and observe how the blue square changes to test the glasses.

• If your lenses filter blue light, the blue square will turn black or dark gray.
• If the blue square remains blue, it means your glasses are not blocking enough blue light.

Orange and red lenses will make the blue portion of an RGB color chart appear darker. 'RGB' stands for 'Red, Green, Blue,' and it displays all the colors visible to the human eye. Search for an 'RGB color chart' or 'RGB color wheel' and examine it through your glasses to check the blue light blocking capabilities.

• The blue section of the chart or wheel will turn gray or black if your lenses block blue light. The green section will appear more vivid.
• The darker the green, the better (especially with orange and red lenses designed for nighttime use).

The spectral report will show the entire spectrum of light blocked by the lenses. If the manufacturer is reputable, they will have no hesitation in sending you the report (if they insist you trust them, that's a warning sign). For computer glasses, ensure they block at least 30% of blue light before purchasing.

• Yellow lenses worn at night or for driving should block about 65-70% of blue light.
• Orange and red lenses for nighttime use designed for sleep should block 95-100% of blue light.
• No matter the lens color—white, yellow, orange, or red—the spectral report is helpful.

Wear the glasses for a few days and notice if your sleep improves. If your glasses block enough blue light, you'll find that both the duration and quality of your sleep will improve, giving you more energy during the day and boosting work productivity. Wearing blue light blocking glasses is harmless, even if the glasses don't reflect blue light.

• Many manufacturers offer trial periods for customers to test the effectiveness.
• This trial works for any lens color, but orange or red lenses will have a greater impact on sleep than clear lenses.
• The effect is especially noticeable for 'night owls' who stay up late regularly.
• Blue light blocking glasses don't help with eye strain. They simply improve your sleep by counteracting the disruptive effects of blue light on your biological clock (the feeling that it's time to sleep).

• The price of blue light blocking glasses doesn't always reflect their effectiveness. However, glasses that block at least 30% of blue light and have an anti-glare coating are rarely priced below 40 USD (900,000 VND).
• If the manufacturer refuses to provide a report or you have doubts about its accuracy, take the glasses to an optometrist or an independent company with a spectrometer. They can tell you how much blue light is blocked and at which frequencies.

• Some companies offer 'blue light pens' (small flashlights that emit blue light) that you can shine through the lenses to prove their blue light blocking capabilities. However, these pens usually emit purple light (which is right next to blue on the spectrum), not blue. This marketing trick is often seen as deceptive.