Usability and Acceptability of Corneal-Plane α-opic Dosimetry in a 24 h Field Trial

Background: Ocular light exposure influences our human physiology and be- havior. Recently, an international expert group published recommendations (Brown et al., PLoS Biology, DOI: 10.1371/journal.pbio.3001571) for criterion light levels during day- time, evening and nighttime that support these non-visual influences. However, it is cur- rently unknown whether these criterion light-exposure levels are met in practice, necessi- tating wearable dosimeters. Here, we evaluated the use of a novel spectacle-mounted cor- neal-plane light dosimeter (Stampfli et al., CIE Proceedings, DOI: 10.25039/x48.2021.op18; https://light-dosimeter.ch/ accessed on 31 August 2022) to measure ocular light exposure. Methods: Eighteen (n = 18) full-time students (20.1 ± 1.6 years, 9 female) living in the Ox- ford Ring Road wore a light dosimeter-measuring photopic illuminance, CCT, α-opic ir- radiance and α-opic equivalent daylight illuminance (EDI) following CIE S 026/E:2018 as well as device tilt for a period of appr oximately 24 h in an unconstrained ecological set- ting. After the 24 h measurement period, participants completed Likert -scale question- naires probing social, usability and intrinsic motivation. Additionally, we asked for open- ended feedback and comments, which we subjected to a thematic analysis. Results: Ocu- lar light exposure profiles could be readily measured with the corneal-plane light dosim- eter, producing distinct temporal light exposure patterns that varied between different individuals. Participants rated wearing the device as acceptable and usable. The thematic analysis revealed two main themes that participants were concerned with: size, weight and stability of the device, and positive and negative reactions from other people. Con- clusion: Our study indicates that corneal-plane dosimetry may be feasible for measuring ocular light exposure in the field, leading to novel insights into the relationship between light exposure and physiological outcomes. The study highlights that for long- term use and convenience, miniaturization of sensors for use in the corneal plane may be necessary

Night Matters—Why the Interdisciplinary Field of “Night Studies” Is Needed

The night has historically been neglected in both disciplinary and interdisciplinary research. To some extent, this is not surprising, given the diurnal bias of human researchers and the difficulty of performing work at night. The night is, however, a critical element of biological, chemical, physical, and social systems on Earth. Moreover, research into social issues such as inequality, demographic changes, and the transition to a sustainable economy will be compromised if the night is not considered. Recent years, however, have seen a surge in research into the night. We argue that “night studies” is on the cusp of coming into its own as an interdisciplinary field, and that when it does, the field will consider questions that disciplinary researchers have not yet thought to ask

PySilSub: An open-source Python toolbox for implementing the method of silent substitution in vision and nonvisual photoreception research

The normal human retina contains several classes of photosensitive cell—rods for low-light vision, three cone classes for daylight vision, and intrinsically photosensitive retinal ganglion cells (ipRGCs) expressing melanopsin for non-image-forming functions, including pupil control, melatonin suppression, and circadian photoentrainment. The spectral sensitivities of the photoreceptors overlap significantly, which means that most lights will stimulate all photoreceptors to varying degrees. The method of silent substitution is a powerful tool for stimulating individual photoreceptor classes selectively and has found much use in research and clinical settings. The main hardware requirement for silent substitution is a spectrally calibrated light stimulation system with at least as many primaries as there are photoreceptors under consideration. Device settings that will produce lights to selectively stimulate the photoreceptor(s) of interest can be found using a variety of analytic and algorithmic approaches. Here we present PySilSub (https://github.com/PySilentSubstitution/pysilsub), a novel Python package for silent substitution featuring flexible support for individual colorimetric observer models (including human and mouse observers), multiprimary stimulation devices, and solving silent substitution problems with linear algebra and constrained numerical optimization. The toolbox is registered with the Python Package Index and includes example data sets from various multiprimary systems. We hope that PySilSub will facilitate the application of silent substitution in research and clinical settings

The HiSCORE Project

A central question of Astroparticle Physics, the origin of cosmic rays, still remains unsolved. HiSCORE (Hundred*i Square-km Cosmic ORigin Explorer) is a concept for a large-area wide-angle non-imaging air shower detector, addressing this question by searching for cosmic ray pevatrons in the energy range from 10TeV to few PeV and cosmic rays in the energy range above 100TeV. In the framework of the Tunka-HiSCORE project, first prototypes have been deployed on the site of the Tunka-133 experiment, where we plan to install an engineering array covering an area of the order of 1km2. On the same site, also imaging and particle detectors are planned, potentially allowing a future hybrid detector system. Here we present the HiSCORE detector principle, its potential for cosmic ray origin search and the status of ongoing activities in the framework of the Tunka-HiSCORE experiment

Recommendations for daytime, evening, and nighttime indoor light exposure to best support physiology, sleep, and wakefulness in healthy adults

Ocular light exposure has important influences on human health and well-being through modulation of circadian rhythms and sleep, as well as neuroendocrine and cognitive functions. Prevailing patterns of light exposure do not optimally engage these actions for many individuals, but advances in our understanding of the underpinning mechanisms and emerging lighting technologies now present opportunities to adjust lighting to promote optimal physical and mental health and performance. A newly developed, international standard provides a SI-compliant way of quantifying the influence of light on the intrinsically photosensitive, melanopsin-expressing, retinal neurons that mediate these effects. The present report provides recommendations for lighting, based on an expert scientific consensus and expressed in an easily measured quantity (melanopic equivalent daylight illuminance (melaponic EDI)) defined within this standard. The recommendations are supported by detailed analysis of the sensitivity of human circadian, neuroendocrine, and alerting responses to ocular light and provide a straightforward framework to inform lighting design and practice

Photoreceptor inputs to pupil control

The size of the pupil depends on light level. Watson and Yellott (2012) developed a unified formula to predict pupil size from luminance, field diameter, age, and number of eyes. Luminance reflects input from the L and M cones in the retina but ignores the contribution of intrinsically photosensitive retinal ganglion cells (ipRGCs) expressing the photopigment melanopsin, which are known to control the size of the pupil. We discuss the role of melanopsin in controlling pupil size by reanalyzing an extant data set (Bouma, 1962). We confirm that melanopsin-weighted quantities, in conjunction with Watson and Yellott's formula, adequately model intensity-dependent pupil size. We discuss the contributions of other photoreceptors into pupil control

Wearable Light Loggers: From Optical Radiation to Health-Related Metrics

The past decades have generated compelling laboratory evidence showing that light exposure profoundly impacts on human circadian physiology through a pathway connecting a subset of ganglion cells in the retina to the hypothalamus. While these laboratory studies generally demonstrate the biological capacity of non-visual photoreceptive pathways to respond to light, the significance and relevance of light exposure in the real world does not immediately follow from "biological capacity" studies. One key component for understanding the impact of light exposure in the real world is measuring patterns of light exposure. In the past years, wearable light loggers have become available to accomplish this task. In this webinar hosted by the Color Technical Group, Manuel Spitschan will review new developments in this area and discuss challenges and research gaps that need to be addressed