Dynamic lighting in a Pediatric ICU: Effects on staff visual comfort and circadian biomarkers

Various regulations and standards propose optimal thresholds for metrics related to the visual system, such as illuminance, and those related to circadian rhythms, such as circadian stimulus. Establishing optimal thresholds is crucial in shift-based workspaces—like hospital intensive care units, where the electric lighting impacts staff, affecting visual comfort, circadian rhythms and job performance, ultimately influencing patient health. However, recommended thresholds often misalign with real-world conditions. There is a contradiction between static illuminance thresholds and variable CS thresholds, which depend on whether melatonin should be promoted or suppressed. Furthermore, thresholds are often set without considering space characteristics, activities or user needs. The recommended lighting levels remain largely unchanged, failing to reflect actual requirements. This study discusses the daily time-adjustment of static electric lighting configurations with illumination levels differing from the recommended levels oriented to the needs of ICU healthcare staff and their visual comfort, as determined through user satisfaction surveys. To ensure that the established lighting does not negatively impact health and circadian rhythm synchronization, experiments have been conducted, and blood and urine samples have been collected to measure the values of key biological markers cortisol and melatonin. While the study does not aim to present the optimal lighting solution, it provides effects of two practical scenarios comparison respect to a typical lighting fixture applicable in ICU settings. Special consideration is given to minimizing the impact on patients during night shift as a boundary condition among compatibility with medical surveillance, recognizing that total darkness is not feasible in such environments.