Wearable monitoring for evaluating non-visual effects of light on health and well-being: a systematic review

The impact of light on circadian rhythms, alertness, and well-being is widely recognized. Advancements in lighting research emphasize the importance of understanding these effects, mainly by measuring personal light dose, considering timing, intensity, duration, and spectrum. Therefore, new monitoring devices have been developed to measure individual light exposure and improve light dose analysis on circadian rhythms. Currently available devices include wearable sensors and low-cost, open-source, solutions that are adaptable and widely applicable. These wearables, when used alongside other measurement tools and standardized protocols, offer a comprehensive means to study light exposure in real-world conditions. However, despite the growing availability of these technologies, there is a lack of systematic evaluation regarding their accuracy, reliability, and applicability in both research and practical settings. This review explores recent developments in wearable technologies for monitoring the non-visual effects of light on humans. Emphasizing the role of circadian rhythms, it discusses how light exposure influences alertness, mood, and overall health and well-being. A range of monitoring devices is evaluated, highlighting variations in functionality and way of wearing, while identifying data reliability and standardization gaps. This review paper aims to emphasize the importance of integrating different measurement tools, combining environmental monitoring (e.g., light exposure), physiological assessments (e.g., heart rate, body temperature), and personal feedback (e.g., subjective reports on alertness and well-being). The review results highlight a more holistic approach to studying the impact of light on humans. Furthermore, it proposes future research directions and practical applications to enhance health outcomes through personalized light management strategies.