National Anti-Junk Light Day 💡

Overview

National Anti-Junk Light Day is observed annually on September 10th, raising awareness of "junk light" — the blue and green wavelengths emitted by screens, LEDs, and fluorescent bulbs that can disrupt sleep and eye health. The day was founded in 2018 by TrueDark, a company that makes light-filtering glasses, with the name deliberately echoing "junk food" to frame certain kinds of artificial light as something to consume in moderation. The concern isn't just personal: light pollution now affects an estimated 83% of the world's population, and a 2016 global atlas found the Milky Way hidden from more than a third of humanity, including nearly 80% of North Americans. The day is a nudge to rethink screen habits after dark and consider how the lights around you affect both your sleep and the night sky.

Origin and story

National Anti-Junk Light Day was founded in 2018 by TrueDark, a company that makes eyewear designed to filter out disruptive wavelengths of artificial light. The name is a deliberate riff on "junk food" — the idea being that certain kinds of light, like certain kinds of food, aren't harmful in small doses but cause real problems when they dominate your daily intake, especially after dark.

The science behind the term is well established: research from institutions including Harvard Medical School has found that blue light exposure in the evening suppresses melatonin and shifts the body's internal clock more than warmer-toned light does, making it harder to fall asleep and lowering sleep quality. The effect isn't limited to bedrooms, either. A 2016 atlas of global light pollution, published in the journal Science Advances, found that more than 80% of the world's population lives under light-polluted night skies, and that the Milky Way itself is now hidden from more than a third of humanity — including nearly 80% of people in North America. The holiday's goal is modest by comparison: one day a year to notice how much artificial light surrounds you, and to make small, deliberate choices about it.

Quick facts

• DateSeptember 10
• TypeHealth / Awareness
• Great forNight owls, Stargazers, Anyone who doomscrolls in bed

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Ways to celebrate

The day is built around small, practical swaps rather than a total ban on screens, so start with whichever of these fits your evening routine.

Turn on night mode

Most phones, tablets, and laptops have a built-in warm-light or "night shift" setting — switching it on after sunset is the single easiest way to cut evening blue-light exposure.

Swap one bulb

Warmer, dimmer bulbs in bedrooms and living rooms produce far less of the blue and green light linked to disrupted sleep than standard daylight-toned LEDs.

Look for the stars

Step outside after dark and see how much of the sky is actually visible from where you live — a small, direct way to feel the light-pollution numbers rather than just read them.

Helpful resources: Blue Light Has a Dark Side (Harvard Health Publishing)

Fun facts

• National Anti-Junk Light Day was founded in 2018 by TrueDark, a company that makes light-filtering eyewear designed to block disruptive wavelengths.
• The term "junk light" deliberately echoes "junk food" — framing blue and green light from screens and LEDs as something to consume in moderation, not eliminate entirely.
• Research from Harvard Medical School has found that blue light in the evening suppresses melatonin and shifts the body's internal clock more than warmer-toned light does.
• A 2016 global light pollution atlas published in Science Advances found the Milky Way hidden from more than one-third of humanity, including nearly 80% of North Americans.
• Light pollution doesn't just affect stargazing — it can also disrupt wildlife migration patterns, since many species rely on natural light and darkness cues to navigate and reproduce.

Sources and attribution

• National Anti-Junk Light Day (National Today)
• Light Pollution Hides Milky Way From 80 Percent of North Americans (NPR)
• Light pollution (Wikipedia)

External links may lead to third-party websites.

Continue your streak

Open one more holiday before you go to build daily momentum.

• Yesterday: National Teddy Bear DayQuick context from the day before.
• Tomorrow: National Make Your Bed DayKeep the streak going with tomorrow's pick.
• Random pick: National Two Different Colored Shoes DayJump to another surprise holiday.
• Popular: National Ugly Sweater DayA fan favorite with broad appeal.

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FAQ

When is National Anti-Junk Light Day?

It is observed on September 10 each year.

What is National Anti-Junk Light Day?

National Anti-Junk Light Day is observed annually on September 10th, raising awareness of "junk light" — the blue and green wavelengths emitted by screens, LEDs, and fluorescent bulbs that can disrupt sleep and eye health. The day was founded in 2018 by TrueDark, a company that makes light-filtering glasses, with the name deliberately echoing "junk food" to frame certain kinds of artificial light as something to consume in moderation. The concern isn't just personal: light pollution now affects an estimated 83% of the world's population, and a 2016 global atlas found the Milky Way hidden from more than a third of humanity, including nearly 80% of North Americans. The day is a nudge to rethink screen habits after dark and consider how the lights around you affect both your sleep and the night sky.

How do people celebrate National Anti-Junk Light Day?

Swap screen time for a warmer light source after dark, turn on night mode or blue-light filtering on your devices, or step outside to look for stars.

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