Visual and Non-visual Effects of Light on Health in Neonatal Intensive Care Units (NICU)

Abstract

Only in recent years, scientists have uncovered the importance of lighting design, beyond facilitating vision. Human eyes function in a dual manner, and the second function is to facilitate healthy circadian rhythms. The photobiological research is still evolving, but preliminary findings show that light-sensing opsins within the retina interact with genes oscillating to circadian rhythms. Photoreceptors photopsin (OPN1), melanopsin (ONP4) and neuropsin (OPN5) send information that impacts health, vision, and circadian rhythms. Research in neonatal intensive units (NICU) shows that circadian light regimes can exert a positive influence on a baby's brain and eye development, and metabolic body functions. It is necessary to design, control, and manage the intensity and spectra of light in NICU settings to support the healthy development for premature babies. Currently, design guidelines for circadian lighting in healthcare settings are not well established; and there are not any tools that can simulate the neuropic light levels in built environments. Hence, this thesis addresses to a need for a tool that can predict the visual and non-visual effects of lighting decisions within a design workflow. LARK Multi-Spectral Lighting simulation tool was developed in 2015 as a Rhino Grasshopper plugin to simulate the non-visual effects of lighting. The objectives of this research are i) to further develop LARK to quantify the recently discovered non-visual opsin neuropsin along with photopsin and melanopsin, and ii) to demonstrate simulation workflows for NICU settings to perform robust and accurate daylighting and electric lighting analyses for occupants including patients, clinicians, and patient families. Sample workflows are exemplified to study the role of daylight and electric lighting in a NICU setting with the goal of improving design decisions. Different date, time, and weather conditions, spectral properties of glazing, surface materials, and electric light sources are simulated, and the resulting photopic, melanopic, and neuropic light levels are analyzed. The results of this thesis show that healthy lighting recipes, which satisfy the criteria for all three opsins, can be prescribed through dynamic commissioning practices for shading and tunable electric lighting systems, in addition to thoughtful design decisions such as appropriate glazing and material selections.