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

Stefani, Oliver; Freyburger, Marlène; Veitz, Simon; Basishvili, Tamar; Meyer, Martin; Weibel, Janine; Kobayashi, Kinji; Shirakawa, Yasuhiro; Cajochen, Christian

doi:10.1101/2020.04.21.771832

Cited by 3 publications

(1 citation statement)

References 75 publications

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“…Research suggests that there is a linkage between CCT, alertness and cognitive performance. From a study with 16 subjects, exposed to different artificial light settings for two consecutive hours during evening sessions, Chellappa et al (2011) and Stefani et al (2020) concluded that commercially available compact fluorescent lights with different color temperatures could significantly affect circadian physiology and cognitive performance. As for DWl, studies have shown that suppression of melatonin is more sensitive to light at shorter wavelengths, with the predominance of the blue spectrum as the most effective for the maintenance of circadian functions (Brainard et al, 2001;Thapan et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Seasonal Effects of Daylight Conditions on Occupant Perception and Skin Temperature

Krüger

2022

Front. Sustain. Cities

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Current research on the relationship between daylight and well-being has shown that access to daylight plays a relevant role both in terms of light perception and with respect to physiological mechanisms not directly related to vision. The aim of this paper is to analyze changes in reported light perception and in physiological responses, represented in this case by the skin temperature of research participants (n = 16) across three seasons (winter, spring and summer seasons) in a temperate, mid-latitude location, Karlsruhe, in southern Germany (49°N, 8.5°E). Sessions have been held in thermally stable rooms of a climate chamber, with daylight exposure to two opposing solar orientations of the glazed façade, namely equatorial and non-equatorial orientations, over 5-h morning sessions. Differences in light perception as well as changes in physiology have been observed. Results showed an increased sensitivity of the individuals in terms of light perception to changes in daylight in winter while such sensitivity dropped in spring and summer, with greater daylight availability and diminished lighting variability during sessions. Due to the intrinsic relationship between light perception and circadian entrainment, the same was verified for changes in skin temperature, which were also found to be significantly related to daylight availability. Seasonal influence suggests that variability of brightness and correlated color temperature (CCT) of natural light can affect both psychological and physiological patterns in humans.

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Section: Introductionmentioning

confidence: 99%

Seasonal Effects of Daylight Conditions on Occupant Perception and Skin Temperature

Krüger

2022

Front. Sustain. Cities

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Lack of evidence for the contribution of cone photoreceptors to human melatonin suppression and alerting response to light at night

Fazlali,

Lazar,

Yahya

et al. 2024

Preprint

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Light exposure at night can suppress melatonin production and increase alertness, primarily through the action of melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs). This study investigated whether cone photoreceptors also influence melatonin suppression and subjective alertness using non-visual metameric light emitted from a display. Forty-eight participants with normal trichromatic vision were exposed to three lighting conditions: a baseline (9 lxmEDI), constant background (149 lxmEDI), and cone-modulated flickering light targeting different cone combinations and post-receptoral channels (149 lxmEDI) for 2 hours after their habitual bedtime. Salivary melatonin levels and subjective alertness were measured throughout a 9-h protocol. Bayesian analysis showed that cone-modulated flickering light did not significantly affect melatonin suppression or alertness, providing evidence against the hypothesis that cone photoreceptors contribute to these non-visual effects of light. In conclusion, our results suggest cone photoreceptors do not play a measurable role in light's effects on melatonin suppression and subjective alertness at night.

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Melanopic Limits of Metamer Spectral Optimisation in Multi-Channel Smart Lighting Systems

et al. 2021

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Modern indoor lighting faces the challenge of finding an appropriate balance between energy consumption, legal requirements, visual performance, and the circadian effectiveness of a spectrum. Multi-channel LED luminaires have the option of keeping image-forming metrics steady while varying the melanopic radiance through metamer spectra for non-visual purposes. Here, we propose the theoretical concept of an automated smart lighting system that is designed to satisfy the user’s visual preference through neural networks while triggering the non-visual pathway via metamers. To quantify the melanopic limits of metamers at a steady chromaticity point, we have used 561 chromaticity coordinates along the Planckian locus (2700 K to 7443 K, ±Duv 0 to 0.048) as optimisation targets and generated the spectra by using a 6-channel, 8-channel, and 11-channel LED combination at three different luminance levels. We have found that in a best-case scenario, the melanopic radiance can be varied up to 65% while keeping the chromaticity coordinates constant (Δu′v′≤7.05×10−5) by using metamer spectra. The highest melanopic metamer contrast can be reached near the Planckian locus between 3292 and 4717 K within a Duv range of −0.009 to 0.006. Additionally, we publish over 1.2 million optimised spectra generated by multichannel LED luminaires as an open-source dataset along with this work.

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

Cited by 3 publications

References 75 publications

Seasonal Effects of Daylight Conditions on Occupant Perception and Skin Temperature

Seasonal Effects of Daylight Conditions on Occupant Perception and Skin Temperature

Lack of evidence for the contribution of cone photoreceptors to human melatonin suppression and alerting response to light at night

Melanopic Limits of Metamer Spectral Optimisation in Multi-Channel Smart Lighting Systems

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