Andersen, MarilyneHartmeyer, Steffen2025-01-152025-01-152025-01-15202510.5075/epfl-thesis-10959https://infoscience.epfl.ch/handle/20.500.14299/242779Modern life, predominantly spent indoors, has profoundly altered natural patterns of light exposure, including the intensity, spectral composition, and timing of light that humans experience daily. These changes are particularly relevant given the growing understanding of how light influences not only visual processes but also numerous physiological and psychological functions like circadian rhythms, sleep, and alertness. As modern environments increasingly disconnect individuals from natural light cycles, it is crucial to explore how life with light can be better aligned with human biology to promote health and wellbeing. An important tool in this effort is light-dosimetry â the measurement of personal light exposure with wearable sensors. Light-dosimetry allows for the epidemiological assessment of personal light exposure in real-life settings across a variety of populations, such as different occupations, cultures, and environments, and serves as an important correlate of non-visual responses and health outcomes. Despite its potential, light-dosimetry is still a relatively new field and lacks standardised operating procedures, which limits the comparability of studies and the ability to interpret research outcomes. At the same time, the accumulating evidence from laboratory studies on the effects of light on non-visual responses increasingly demands the assessment of these relationships in real-life settings. To address these challenges, this thesis seeks to advance the field of light-dosimetry by addressing methodological challenges and exploring novel approaches. It reviews important considerations in the measurement of personal light exposure and presents various metrics for quantifying and analysing the complex data generated by wearable light sensors. Additionally, the thesis introduces novel approaches for capturing the spatiotemporal dynamics and spectral characteristics of personal light exposure, offering a more nuanced understanding of lighting conditions experienced in real-life. The practical applications of these advances are demonstrated in intervention and observational studies, exploring how light-dosimetry can be used to assess the impact of different lighting conditions in built environments and workplaces, and evaluate their effects on healthrelated outcomes. By examining light exposure in real-world settings, this research highlights the complex interaction between lighting design and individual behaviour, showing how both environmental factors and personal habits shape light exposure patterns. It also demonstrates the utility of light-dosimetry in linking exposure to non-visual responses and health-related outcomes, such as in office workers or vulnerable populations like nightshift workers. This thesis contributes to integrative lighting research by laying the groundwork for the further development of light-dosimetry to support studies on the role of light in real-life. It provides a rationale for the importance of accurate light measurement, proposes novel approaches for improving the assessment of personal light exposure, and highlights the role of light-dosimetry in linking lighting conditions with health outcomes. Through these contributions, this thesis offers an important step forward in integrating the benefits of light into modern living, with the ultimate goal of promoting health and wellbeing through informed, evidence-based lighting practices.enlighthealthdosimetrydaylightcircadiannon-visualintegrative lightingspectrumthesis::doctoral thesis