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What is blue light vs white light?

What is blue light vs white light?

Blue light and white light are different types of visible light that have varying wavelengths and effects on the human body. Understanding the differences between blue light and white light is important, especially given the increased exposure to blue light from electronic devices. This article will examine what blue light and white light are, their wavelength ranges, sources, effects on health and sleep, and tips for managing blue light exposure.

What is Blue Light?

Blue light is a type of visible light that has wavelengths ranging from around 380-500 nanometers (nm). It is part of the visible light spectrum that appears blue to the human eye. Some key facts about blue light:

Wavelength range 380-500 nm
Color Blue
Sources The sun, electronic devices (phones, tablets, TVs), fluorescent and LED lighting

Blue light is emitted naturally by the sun and is part of the light spectrum that helps regulate the human body’s internal clock and circadian rhythms. In the past few decades, we have been exposed to increasing amounts of artificial blue light through electronic devices, LED lighting, and fluorescence.

What is White Light?

White light is visible light that appears white to the human eye. It is composed of a full spectrum of visible light wavelengths, including red, orange, yellow, green, blue, indigo, and violet. Key facts about white light:

Wavelength range Full visible spectrum: 380-750nm
Color White (mix of all colors)
Sources The sun, incandescent bulbs, fluorescent and LED bulbs

White light contains a balanced mix of all the colors of the visible spectrum. Natural sunlight is an example of white light. Other sources include incandescent light bulbs, which emit a full spectrum, and fluorescent and LED bulbs, which combine colored LEDs to form white light.

Wavelength Ranges

The key difference between blue and white light lies in their wavelength ranges:

  • Blue light waves are shorter, with wavelengths between about 380-500nm.
  • White light contains the full visible spectrum, with wavelengths between 380-750nm.

Here is a visual comparison of the wavelength ranges:

Light Type Wavelength Range
Blue light 380-500 nm
White light Full visible spectrum: 380-750 nm

As you can see, blue light only makes up one section of the full visible light spectrum that composes white light.

Light Sources

Blue light and white light also differ in their sources:

Blue Light Sources

  • The sun – Sunlight contains blue wavelengths.
  • Electronic devices – Phones, tablets, TVs, and computers emit a lot of blue light from their screens.
  • Fluorescent and LED lighting – These bulbs emit some blue wavelengths.

In nature, the primary source of blue light is sunlight. But in the modern world, we are exposed to increasing amounts of artificial blue light from tech devices and energy-efficient lighting.

White Light Sources

  • The sun – Sunlight is a natural source of white light.
  • Incandescent bulbs – These traditional bulbs emit a full spectrum of light.
  • Fluorescent and LED bulbs – By combining different colored LEDs, these bulbs can create white light.

The sun emits a continuous spectrum of light including all visible wavelengths that appear white. Incandescent bulbs also emit a full spectrum. Other bulb types use combinations of different colors to form white light.

Effects on Health and Sleep

Blue light and white light can have different effects on the body, especially related to sleep and circadian rhythms.

Blue Light Effects

  • Suppresses melatonin – Blue light suppresses the production of melatonin, the sleep hormone. This makes it harder to fall and stay asleep.
  • Disrupts circadian rhythms – Circadian rhythms regulate sleep/wake cycles. Blue light exposure at the wrong times can disrupt healthy rhythms.
  • Eye strain – Blue light scatters more and leads to digital eye strain when staring at screens.

While blue light from the sun helps regulate circadian rhythms and waking us up, overexposure to artificial blue light at night can be disruptive for sleep and health.

White Light Effects

  • Natural regulator – White light from the sun helps entrain healthy circadian rhythms.
  • Alertness – Daytime white light exposure boosts alertness and performance.
  • Better sleep – White light is less disruptive than blue light alone at night.

White light has positive effects in the daytime by enhancing alertness. At night, white light is less disruptive for sleep than blue light due to its fuller spectrum.

Tips for Managing Blue Light Exposure

Here are some tips to help manage blue light exposure from electronic devices and lights:

  • Use blue light filters – Enable night shift on devices, install blue light filter apps, or use blue-blocking glasses.
  • Avoid screens before bed – Don’t use phones/tablets an hour before bedtime.
  • Use warm white bulbs – Switch to bulbs with warmer color temperatures at night.
  • Get daylight exposure – Spend time outdoors during the day to help circadian rhythms.

Following healthy sleep hygiene and limiting blue light exposure in the evening can help achieve better sleep quality.


In summary, blue light and white light differ in their wavelength ranges, sources, and effects on the body. Blue light is a smaller portion of the visible spectrum, while white light contains the full spectrum of visible wavelengths. Too much blue light exposure from electronics and lighting at night can disrupt circadian rhythms and sleep. Following some simple tips like limiting screen time before bed, using blue light filters, and getting enough daytime light exposure can help achieve good sleep and health.