Light exposure profoundly influences human health, regulating circadian rhythms and impacting wakefulness and sleepiness. Estimating the effects of light exposure under everyday conditions requires personal, wearable light logging and dosimetry approaches. This article introduces the MeLiDos Project (2023–2026), supported by the European Association of National Metrology Institutes (EURAMET). The project’s first branch defines quality indices and calibration standards for wearable light loggers, adapting existing metrological standards to their smaller size and distinct purpose in the field rather than the laboratory. The second branch develops a software ecosystem, including the open-source R software package LightLogR, designed to manage the increasing volume of data, ensuring reusability, accessibility and interoperability of data. The third branch explores the potential of spatially resolved light dosimetry. The MeLiDos Project anticipates advancements in wearable light metrology, paving the way for optimizing human health and well-being through wearable light logging technologies. 

The spectral distribution is a fundamental property of non-monochromatic optical radiation. It is commonly used in research and practical applications when studying how light interacts with matter and living organisms, including humans. In the field of lighting, misconceptions about the spectral distribution of light are responsible for unfounded claims, which pervade the scientific and technical communities. Starting from the definition of the spectral distribution, this paper describes the ambiguities and errors associated with a purely graphical analysis of the spectral distribution. It also emphasizes the importance of considering the particle nature of light in research involving both visual and non-visual effects, which implies using the spectral distribution expressed in the photon system of units, a system that has been seldom used in lighting research for historical reasons. The authors encourage lighting engineers and researchers to determine which system is best suited to their work and then proceed with the correct use of spectral distributions and of spectral weighting functions for applications involving optical radiation. © The Chartered Institution of Building Services Engineers 2024.

The widespread use of electric lighting has revolutionised society but brought unintended consequences, notably light pollution, impacting ecosystems and human circadian rhythms. Concerns about anthropogenic light at night (ALAN) have prompted innovative solutions, such as spectral tuning of light sources. In Europe, a recent focus involves the enforcement of red light in outdoor settings to minimise ALAN’s impact, particularly on bats. This mini review synthesises literature to provide an overview of the advantages and disadvantages of the use of red light outdoors. There is a need for further examination of the potential ecological consequences of red light, considering challenges in lighting design functionality and broader impacts on diverse species.

Insects play a critical role in providing numerous ecosystem services. However, insect diversity and biomass have been declining dramatically, with artificial light being suggested as a contributing factor. Despite the importance of understanding the dose–effect responses of insects to light emissions, these responses have been rarely studied. We examined the dose–effect responses of the greater wax moth (Galleria mellonella L.) to different light intensities (14 treatments and a dark control) by observing their behavioural responses in a light-tight box equipped with a LED light source (4070 K) and infrared cameras. Our findings reveal dose–effect responses to light, as the frequency of walking on the light source increased with higher light intensity. Additionally, moths exhibited jumps in front of the light source and jump frequency increased with light intensity. No direct flight-to-light behaviour or activity suppression in response to light was observed. Based on our analysis of the dose–effect responses, we identified a threshold value of 60 cd/m2 for attraction (walking on the light source) and the frequency of jumps. The experimental design in this study offers a valuable tool for investigating dose–effect relationships and behavioural responses of various species to different light levels or specific light sources. © 2023, The Author(s).

Circular economy is becoming an important topic for lighting design, research, and industry. Recent legislation, like the EU's ecodesign regulation, has established circularity, reparability, and recyclability as requirements for the industry. This article investigates what happens at the end-of-life stages of lighting products through questionnaires and interviews conducted with experts in Sweden and France. The focus is on understand the impact of the new EU requirements on industrial practice in France and Sweden. Moreover, the article provides ideas for practical improvement of both product recyclability and waste handling of luminaires and light sources.

Light at night (LAN) enables humans to extend their lifestyle and exploration, cultivates economic growth, and increases the perception of safety. On the other hand, LAN has been connected to adverse health outcomes, such as circadian disruption, mood effects, and increased breast cancer incidence risk in humans. Studies investigating health outcomes of LAN utilize a variety of methods sometimes resulting in conflicting outcomes. We conducted a systematic review focusing on the experimental methods and health outcomes of LAN studies. While most studies found a negative impact of LAN on human health, lighting conditions were not adequately reported or controlled in many cases. Recommendations are provided for future research studies investigating LAN effects on human health outcomes. 

Current standards for light environments are based on technical requirements, e.g. luminance, uniformity, and illuminance, and do not necessarily describe all parts of the light experience to ensure visual comfort from a user perspective. Including experience-related requirements would most likely yield better lighting comfort. To do that, new methods for specifying and measuring the user experience are needed. This paper describes a pilot study exploring a new method to analytically assess perceived lighting properties by using a trained human panel and thus make human assessments more objective. The methodology is built on established sensory methods, where the human senses are used in product assessments, traditionally applied within e.g. the food, packaging, and car industries. An analytical panel comprising eight persons fulfilling specific selection criteria were recruited and trained to assess lighting products in a multi-sensory laboratory. The results show that the panelists were able to assess lighting by distinguishing between attributes and products. Significant differences were identified between the different luminaires, both in terms of sensory and physical properties, e.g. readability and glare. Conclusively, analytical sensory methods can be applied to lighting to assess luminaires in a non-subjective way. Physical and sensory attributes do not, however, always co-vary, which shows that data from physical and sensory measuring methods provide complementary information about light quality. This knowledge may in turn be applied in tools supporting the communication between different professions in lighting design and procurement to promote light environments that are both energy efficient and desirable from an end-user perspective.

LED lighting solutions sometimes give rise to optical flicker. In most cases, the temporal modulations are too fast to be perceived directly, but may still be noticed through stroboscopic effects. We report on an investigation on how people experience the lighting in an office where two LED lamps are modulated separately with different frequencies. The test subjects performed tasks for evaluation of perception, attention and reaction time. The subjects are found to be affected by the modulated light as the reaction times are shorter and the attention test scores are higher in modulated lighting compared to constant lighting. Furthermore, the study confirms that the stroboscopic effect depends on the nature of the tasks and that it is more easily perceived at lower frequencies but noticed up to at least 400 Hz.

Nuvarande belysningsstandarder baseras enbart på tekniska krav, såsom ljusstyrka, jämnhet och luminans. Att även inkludera upplevelsebaserade krav skulle troligen främja bättre ljuskomfort, men även mer energieffektiva ljusmiljöer och produkter. Kunskapen om hur upplevda belysningsparametrar kan beskrivas är dock begränsad. Detta hämmar fastighetsägare och brukare att precisera önskvärda ljusmiljöer, liksom belysningstillverkare att utveckla produkter för nya marknader och tillämpningar. Syftet med detta forskningsprojekt var att utveckla och tillämpa sensoriska metoder på belysning. Till skillnad från tidigare metoder möjliggör sensoriska metoder objektiva bedömningar av upplevda belysningsparametrar.

En analytisk panel bestående av åtta personer som uppfyller särskilda urvalskriterier rekryterades och tränades att bedöma belysningsprodukter i ett multisensoriskt laboratorium på SP Sveriges Tekniska Forskningsinstitut i Borås. Metodutvecklingen fokuserade särskilt på en effektiv träningsprocedur, hantering av ögats adaption, samt bedömning av färg och skuggningar. Förutom laboratorie-försök undersöktes möjligheten att genomföra analytiska bedömningar i en verklig kontext med samma försöksuppställning och panel.

Resultaten visar att det är möjligt att använda sensorisk metodik för att genomföra objektiva belysningsbedömningar av armaturer; paneldeltagarna kunde skilja mellan attribut och prover. Signifikanta skillnader identifierades mellan de olika armaturerna, både i form av sensoriska och fysikaliska egenskaper såsom läsbarhet och bländning. Fysikaliska och sensoriska parametrar samvarierar dock inte alltid, vilket visar att fysikaliska och sensoriska mätningar ger kompletterande information om belysningskvalitet. Vidare visade bedömningsförsök i en verklig kontext att samma resultat uppnåddes som i laboratoriet, men med lägre signifikans, vilket verifierar metodens tillämpbarhet på belysning.

Den genererade kunskapen väntas på sikt bidra till utveckling av verktyg som stödjer kommunikationen mellan olika professioner inom ljusdesign och planering och på så vis främja mer önskvärda och energieffektiva ljusmiljöer.

The lighting in the workplace is known to have a significant effect on the workers’ well-being and alertness. It also affects sleep/wake-cycles and mood. The aim of this pilot study is to investigate a method to evaluate non-visual effects of variable lighting in workplaces using both self-assessed and physical data. The lighting in two offices was varied according to pre-programmed schedules, including daylight simulating scenario for two weeks and activity promoting scenario for two weeks. The method was successful and provided interesting results on the measured physical data. The resting pulse was lowered and the sleep quality improved for the test subjects during the weeks of dynamic office lighting.