5 Things You Didn’t Know About Blue Light

Mavra Masood and Abraham Abdulhak MD

Blue light is a form of visible light within the electromagnetic spectrum and has a wavelength between 400-500 nm.1 Visible light is the type of light we can see and ranges from wavelengths of 400-700nm.2 It’s helpful to recall the mnemonic ROYGBIV, which represents the colors of a rainbow that is visible light. Typical sources of blue light include:

  • sunlight
  • lightbulbs
  • computer screens
  • television screens
  • cellphones

Here are 5 facts you might not know about blue light:

1. The sun emits way more blue light than your devices

Studies comparing blue light intensity from different sources found that the sun emits blue light that is up to 1000 times stronger than that produced by several electronic devices!3 So while we may be spending more time on our screens nowadays, the sun is still the most significant source of blue light exposure in our daily lives.

2. Blue light can cause hyperpigmentation

While we don’t know exactly how blue/visible light causes hyperpigmentation, studies show that visible light can cause hyperpigmentation, especially in darker complexions. This pigmentation can persist for more than 2 weeks. In lighter skin tones, visible light can cause the skin to appear more red.2 Postinflammatory hyperpigmentation, which is more common in deeper skin types, can also be affected by visible light.2

3. Not all sunscreens protect against blue light

UV radiation encompasses shorter wavelengths (280-400 nm) than visible light and contributes to the development of skin cancer, photoaging, and hyperpigmentation. Thus, we need to be applying sunscreen daily and use sun safe practices!4 Broad-spectrum chemical sunscreens protect against UV radiation but are ineffective at blocking visible light. However, broad spectrum physical sunscreens that contain titanium dioxide or zinc oxide not only block UV radiation but may also reduce the effects of visible light on the skin.4,5

4. Blue light can be used to treat some dermatologic conditions

Blue light can be used to treat acne, precancers, and even superficial skin cancers.2 Blue light has anti-inflammatory and anti-proliferative cutaneous effects, which makes it effective in these conditions.2

5. Blue light is important for our circadian rhythm

Exposure to blue light suppresses melatonin secretion, which is a key regulator of our sleep-wake cycle.6 This is great during the daytime and keeps us alert but staying on devices which transmit this light at night may disrupt sleep.

Overall, much is left to be learned about blue light. I hope this article can shed some light on a lesser-known topic! Don’t forget your sunscreen!

 

 

References:

  1. Coats JG, Maktabi B, Abou-Dahech MS, Baki G. Blue Light Protection, Part I-Effects of blue light on the skin. J Cosmet Dermatol. 2021;20(3):714-717. doi:10.1111/jocd.13837
  2. Cohen L, Brodsky MA, Zubair R, Kohli I, Hamzavi IH, Sadeghpour M. Cutaneous Interaction with Visible Light: What Do We Know [published online ahead of print, 2020 Apr 11]. J Am Acad Dermatol. 2020;S0190-9622(20)30551-X. doi:10.1016/j.jaad.2020.03.115
  3. Duteil L, Queille-Roussel C, Lacour JP, Montaudié H, Passeron T. Short-term exposure to blue light emitted by electronic devices does not worsen melasma. J Am Acad Dermatol. 2020;83(3):913-914. doi:10.1016/j.jaad.2019.12.047
  4. Lyons AB, Trullas C, Kohli I, Hamzavi IH, Lim HW. Photoprotection beyond ultraviolet radiation: A review of tinted sunscreens. J Am Acad Dermatol. 2021;84(5):1393-1397. doi:10.1016/j.jaad.2020.04.079
  5. Geisler AN, Austin E, Nguyen J, Hamzavi I, Jagdeo J, Lim HW. Visible light. Part II: Photoprotection against visible and ultraviolet light. J Am Acad Dermatol. 2021;84(5):1233-1244. doi:10.1016/j.jaad.2020.11.074
  6. Wahl S, Engelhardt M, Schaupp P, Lappe C, Ivanov IV. The inner clock-Blue light sets the human rhythm. J Biophotonics. 2019;12(12):e201900102. doi:10.1002/jbio.201900102