Moreover, the effects of light in field settings are often confounded by various uncertainties which may be due to non-photic effects, interindividual variations in sensitivity to light ( 25), differences in the populations studied and the reduced environmental and behavioral control in real-life environments. However, no single action spectrum or proxy will ever provide the complete picture ( 13, 22) for all the testable variations in intensity, timing, duration, and patterns of light exposure that can be created in laboratory settings ( 23, 24). Significantly, melanopsin is the functional photopigment for one of these five photoreceptor types.ДЄccumulating evidence ( 6, 14вЂ“ 21) suggests that the spectral sensitivity of melanopsin is the most successful and parsimonious model to predict responses to medium and long duration exposures to ambient light like circadian phase shifting, or modulations in pupil-size, alertness, and melatonin secretion. It explains and discusses a standardized light metrology ( 12) that is based on five retinal photoreceptor types, each of which has a distinct spectral sensitivity and may contribute to non-visual or NIF responses ( 13). This paper is intended for lighting professionals, policy makers and researchers with a practical interest in lights' eye-mediated NIF effects, chronobiology and health. Light is essential for vision, but starting from the earliest weeks of life ( 1вЂ“ 5) it also drives important non-image-forming (NIF) effects that are powerful determinants of sleep ( 6), circadian rhythms ( 7), alertness ( 8, 9), mood ( 10) and hormone secretion ( 11). This collection of examples suggests ways in which variations in the melanopic content of light over the day can be adopted in strategies that use light to support human health and well-being. Here, we apply this metrology to everyday light sources including a natural daylight time series, a range of LED lighting products and, using the toobox, to a smartphone display screen. The new О±-opic metrology of CIE S 026 enables traceable measurements and a formal, quantitative specification of personal light exposures, photic interventions and lighting designs. Further guidance on this approach is awaited from the participants of the 2nd International Workshop on Circadian and Neurophysiological Photometry (in Manchester, August 2019). Although knowledge concerning the extent to which rods and cones interact with ipRGCs in driving non-visual effects is still growing, a CIE position statement recently used melanopic equivalent daylight (D65) illuminance in preliminary guidance on applying вЂњproper light at the proper timeвЂќ to manipulate non-visual responses. Recent findings continue to confirm that the photopigment melanopsin also plays a role in visual responses, and that melanopsin-based photoreception may have a significant influence on brightness perception and aspects of spatial vision. For a wide variety of ecologically-valid conditions, the melanopsin-based photoreception of ipRGCs has been shown to account for the spectral sensitivity of non-visual responses, from shifting the timing of nocturnal sleep and melatonin secretion to regulating steady-state pupil diameter. The CIE also recently published an open-access О±-opic toolbox that calculates all the quantities and ratios of the О±-opic metrology in the photometric, radiometric and photon systems, based on either a measured (user-defined) spectrum or selected illuminants (A, D65, E, FL11, LED-B3) built into the toolbox. This standard defines five spectral sensitivity functions that describe optical radiation for its ability to stimulate each of the five О±-opic retinal photoreceptor classes that contribute to the non-visual effects of light in humans via intrinsically-photosensitive retinal ganglion cells (ipRGCs). International standard CIE S 026:2018 provides lighting professionals and field researchers in chronobiology with a method to characterize light exposures with respect to non-visual photoreception and responses.

Visual photometric software