Biological effects of high-energy visible light
High-energy visible light (HEV light) is short-wave light in the
Background
Blue LED light
Blue LEDs are often the target of blue-light research due to the increasing prevalence of
Luminous efficiency
Blue LEDs, particularly those used in white LEDs, operate at around 450 nm, where V(λ)=0.038.[5][6] This means that blue light at 450 nm requires about 25 times the radiant flux (energy) for one to perceive the same luminous flux as green light at 555 nm. For comparison, UV-A at 380 nm (V(λ)=0.000 039) requires 25 641 times the amount of radiometric energy to be perceived at the same intensity as green, three orders of magnitude greater than blue LEDs.[7][8] Studies often compare animal trials using identical luminous flux rather than radiance meaning comparative levels of perceived light at different frequencies rather than total emitted energy.[9][10]
Physiological effects
Blue light hazard
A 2019 report by France's Agency for Food, Environmental and Occupational Health & Safety (ANSES) highlights short-term effects on the retina linked to intense exposure to blue LED light, and long-term effects linked to the onset of age-related macular degeneration.[11] Although few studies have examined occupational causes of macular degeneration, they show that long-term sunlight exposure, specifically its blue-light component, is associated with macular degeneration in outdoor workers.[12] However, the CIE published its position on the low risk of blue-light hazard resulting from the use of LED technology in general lighting bulbs in April 2019.[13]
The international standard
Circadian rhythm
The circadian rhythm is a mechanism that regulates sleep patterns. One of the primary factors affecting the circadian rhythm is the excitation of melanopsin, a light sensitive protein that absorbs maximally at 480 nm, but has at least 10% efficiency in the range of 450-540 nm.[16] The periodic (daily) exposure to sunlight generally tunes the circadian rhythm to a 24-hour cycle. However, exposure to light sources that excite melanopsin in the retina during nighttime can interfere with the circadian rhythm. Harvard Health Publishing asserts that exposure to blue light at night has a strong negative effect on sleep.[17] The aforementioned ANSES report "highlights [the] disruptive effects to biological rhythms and sleep, linked to exposure to even very low levels of blue light in the evening or at night, particularly via screens".[18] A 2016 press release by the American Medical Association concludes that there are negative effects on the circadian rhythm from the unrestrained use of LED street lighting and white LED lamps have 5 times greater impact on circadian sleep rhythms than conventional street lamps.[19] However, they also indicate that street lamp brightness is more strongly correlated to sleep outcomes.
Blue light is essential for regulating the circadian rhythm, because it stimulates melanopsin receptors in the eye.[20] This suppresses daytime melatonin, enabling wakefulness. Working in blue-free light (aka yellow light) for long periods of time disrupts circadian patterns because there is no melatonin suppression during the day, and reduced melatonin rebound at night.
Eye strain
Blue light has been implicated as the cause of digital eye strain, but there is no robust evidence to support this hypothesis.[21][22]
Dermatology
As with other types of light therapy, there is no good evidence that blue light is of use in treating
Blue light blocking
Concerns over exposure to blue light has predicated several solutions to decreasing blue light exposure, including disabling or attenuating blue LEDs in displays, color shifting displays towards yellow, or wearing glasses that filter out blue light.
Digital filters
Apple's and Microsoft's operating systems and even the preset settings of standalone computer monitors include options to reduce blue-light emissions by adjusting color temperature to a warmer gamut.
Intraocular lenses
During
Blue light blocking lenses
Lenses that filter blue light have been on the market for a long time in the form of brown-, orange-, and yellow-tinted sunglasses.[34] These tinted lenses were popular for the belief that they enhanced contrast and depth perception, but after early research showing the health risks of blue light exposure,[35][36] became more popular for the purported health benefits of blocking blue light.[37]
The efficacy of blue-blocking lenses in blocking blue light is not disputed, but whether typical exposure to blue light is hazardous enough to require blue blocking lenses is highly disputed.
Aggressive advertisements may contribute to the incorrect public perception of the purported dangers of blue light. Even when research has shown no evidence to support the use of blue-blocking filters as a clinical treatment for digital eye strain, ophthalmic lens manufacturers continue to market them as lenses that reduce digital eye strain.[40]
The UK's General Optical Council has criticised Boots Opticians for their unsubstantiated claims regarding their line of blue-light filtering lenses; and the Advertising Standards Authority fined them £40,000. Boots Opticians sold the lenses for a £20 markup.[41] Trevor Warburton, speaking on behalf of the UK Association of Optometrists stated: "...current evidence does not support making claims that they prevent eye disease."[42].
In July 2022, a Gamer Advantage advert on Twitch channel BobDuckNWeave was banned by the Advertising Standards Authority for making claims that blue light glasses could improve sleep without substantiation.[43][44]
See also
- Fluorescent lamps and health
- Phase response curve
- Ultraviolet light
References
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- ^ US. Department of energy. (2013). Solid-State Lighting Technology Fact Sheet (Optical Safety of LEDs). Available at: https://www.lightingglobal.org/wp-content/uploads/bsk-pdf-manager/82_opticalsafety_fact-sheet.pdf
- ^ "Product family datasheet:Cree® XLamp® XM-L LEDs" (PDF). Cree. p. 4. Archived from the original (PDF) on 2020-11-11. Retrieved 2020-06-19.
- ^ "Technical Data Sheet X42182(Z-power LEDs)" (PDF). pp. 12–13. Archived from the original (PDF) on 2018-12-09. Retrieved 2020-06-19.
- ^ "Colorimetry -- Part 1: CIE standard colorimetric observers". International Organization for Standardization. Retrieved December 9, 2018.
- ^ "Kay & Laby;tables of physical & chemical constants;General physics;SubSection: 2.5.3 Photometry". National Physical Laboratory; UK. Retrieved December 9, 2018.
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- ^ "Light-emitting-diode induced retinal damage and its wavelength dependency in vivo" (PDF). International Journal of Ophthalmology, Vol. 10, No. 2. Feb 18, 2017.
- ^ "LEDs & blue light | Anses - Agence nationale de sécurité Sanitaire de l'alimentation, de l'environnement et du travail". anses.fr. 13 August 2019. Retrieved 2020-01-29.
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- ^ "The IEC addresses characterization of the blue light hazard (MAGAZINE)". LEDs Magazine. 15 January 2014. Retrieved 28 August 2023.
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- ^ "Blue Light Has A Dark Side". Harvard Health Letter. August 13, 2018.
- ^ "LEDs & blue light | Anses - Agence Nationale de sécurité Sanitaire de l'alimentation, de l'environnement et du travail". www.anses.fr. 13 August 2019. Retrieved 2020-01-29.
- ^ "AMA adopts guidance to reduce harm from high intensity street lights". American Medical Association. 14 June 2016. Retrieved 2020-01-29.
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- ^ Rosenfield, Mark (2016). "Computer vision syndrome (aka digital eye strain)". Optometry in Practice. 17 (1).
- ^ LaMotte, Sandee (2023-08-17). "Blue-light glasses don't help with eye strain, major study says". CNN. Retrieved 2023-08-24.
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- ^ Bennett, Timothy J. (2017). "Equipment & Technique". Ophthalmic Photographers' Society.
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- ^ Yousef, Tareq. "There's no evidence that blue‑light blocking glasses help with sleep". Dalhousie News. Retrieved 28 August 2023.
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- ^ Woodley, Matthew (May 31, 2017). "Optical chain fined $69,000 for misleading ad". Insight. Archived from the original on September 3, 2019. Retrieved June 19, 2020.
- ^ Powell, Selina (May 26, 2017). "BOOTS OPTICIANS FINED £40,000 OVER MISLEADING BLUE LIGHT ADVERTISING". Optometry Today.
- ^ "Gamer Advantage LLC". www.asa.org.uk. Advertising Standards Authority. Archived from the original on 21 July 2023. Retrieved 21 July 2023.
- ^ "Gamer Advantage's Blue-Light Glasses". Truth in Advertising. 2022. Archived from the original on 21 July 2023. Retrieved 21 July 2023.