What Is Blue Light And Where Does It Come From?

Medically Reviewed by Whitney Seltman, OD on September 16, 2022

Your tablet, smartphone, laptop and flat screen TV all have one thing in common: They each give off blue light.

It’s one of several colors in the visible light spectrum. The others are:

  • Red
  • Orange
  • Yellow
  • Green
  • Blue
  • Indigo
  • Violet

You may know them by the acronym ROY G BIV. Together, they make the white light you see when the sun -- the main source of blue light -- is shining. Fluorescent and LED (light-emitting diode) light bulbs also give off blue light.

Evidence is growing that shows blue light can:

  • Boost alertness
  • Help memory
  • Raise mood
  • Improve attention span and reaction times

But too much -- especially at night -- could harm your health.

Each color in the visible light spectrum has a different wavelength and energy level. Blue light has shorter wavelengths and higher energy than other colors. Some research shows a link between eye damage and short-wave blue light with wavelengths between 415 and 455 nanometers. Most of the light from the LEDs used in smartphones, TVs, and tablets has wavelengths between 400 and 490 nanometers.

In large amounts, high-energy light from the sun -- like ultraviolet rays and blue light -- can raise your risk of eye disease. That’s caused concerns about whether blue light from digital screens is harmful. More research is needed.

Blue light helps regulate your circadian rhythm, or wake-and-sleep cycle. But watching TV or scrolling through social media too late at night can have the opposite effect. The blue light stimulates your brain, slowing or stopping release of the sleep hormone melatonin. That makes it harder to get a good night’s sleep.

You can’t avoid blue light completely, but there are ways to limit your exposure. They include:

  • Limiting screen time
  • Using screen filters to lower blue light exposure
  • Wearing blue light-blocking glasses, yellow-tinted computer glasses, or glasses with anti-reflective lenses


Show Sources


Prevent Blindness: “Your Sight.”

Molecular Vision: “Effects of blue light on the circadian system and eye physiology.”

International Journal of Ophthalmology: “Research progress about the effect and prevention of blue light on eyes.”

Procedia Manufacturing: “Blue Light: A Blessing or a Curse?”

American Academy of Ophthalmology: “Digital Devices and Your Eyes,” “No, Blue Light From Your Smartphone is Not Blinding You,” “Are Computer Glasses Worth it?”

The Ohio State University Wexner Medical Center: “Does blue light from electronic devices damage your eyes?”

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