Spectral Tuning of White Light Allows for Strong Reduction in Melatonin Suppression without Changing Illumination Level or Color Temperature

Abstract

Studies with monochromatic light stimuli have shown that the action spectrum for melatonin suppression exhibits its highest sensitivity at short wavelengths, around 460 to 480 nm. Other studies have demonstrated that filtering out the short wavelengths from white light reduces melatonin suppression. However, this filtering of short wavelengths was generally confounded with reduced light intensity and/or changes in color temperature. Moreover, it changed the appearance from white light to yellow/orange, rendering it unusable for many practical applications. Here, we show that selectively tuning a polychromatic white light spectrum, compensating for the reduction in spectral power between 450 and 500 nm by enhancing power at even shorter wavelengths, can produce greatly different effects on melatonin production, without changes in illuminance or color temperature. On different evenings, 15 participants were exposed to 3 h of white light with either low or high power between 450 and 500 nm, and the effects on salivary melatonin levels and alertness were compared with those during a dim light baseline. Exposure to the spectrum with low power between 450 and 500 nm, but high power at even shorter wavelengths, did not suppress melatonin compared with dim light, despite a large difference in illuminance (175 vs. <5 lux). In contrast, exposure to the spectrum with high power between 450 and 500 nm (also 175 lux) resulted in almost 50% melatonin suppression. For alertness, no significant differences between the 3 conditions were observed. These results open up new opportunities for lighting applications that allow for the use of electrical lighting without disturbance of melatonin production.

Artificial light at night, in interaction with spring temperature, modulates timing of reproduction in a passerine bird

“…, , Souman et al. ). Indeed, many of the known effects of light pollution are spectral dependent (Longcore et al.…”

“…In particular, in the last decade, a large amount of literature on the biomedical and ecological effects of ALAN has been accumulating (Rich and Longcore 2006, Wyse et al 2011). This has been paralleled by an increased attention to the design, development, and implementation of lighting technologies that are able to reduce such effects, including the use of LED lights as they allow for a more flexible tuning of the spectral properties of illumination (Gallaway et al 2010, Gaston et al 2012, 2014, Souman et al 2018. Indeed, many of the known effects of light pollution are spectral dependent (Longcore et al 2015, Ouyang et al 2018.…”

No evidence for an S cone contribution to the human circadian response to light

“…In the method of silent substitution, pairs of spectra are generated as mixtures of the ten primaries lights which produce a difference in only one photoreceptor class (in this case, the stimulated S cones), while there is no difference in the other photoreceptors (in this case, the silenced L and M cones, rods, and melanopsin). This method has previously been used to examine the effect of melanopsin-only differences in lighting on melatonin suppression [8, 9] (but has a long history in vision science, see [7]).…”

“…We used the German version of the Karolinska Sleepiness Scale (“Bitte bewerten Sie Ihre Müdigkeit” (“sehr wach” [1], “wach” [3], “weder wach noch müde” [5], “müde, aber keine Probleme, wach zu bleiben” [7], “sehr müde, große Probleme, wach zu bleiben, mit dem Schlaf kämpfend” [9]).…”

Changing color and intensity of LED lighting across the day impacts on human circadian physiology, sleep, visual comfort and cognitive performance

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