Date of Award


Document Type


Degree Name

Master of Science


Department of Operational Sciences

First Advisor

Michael E. Miller, PhD


Increased levels of time are spent indoors, decreasing human interaction with nature and degrading photoentrainment, the synchronization of circadian rhythms with daylight variation. Military imagery analysts, among other professionals, are required to work in low light level environments to limit power consumption or increase contrast on display screens to improve detail detection. Insufficient exposure to light in these environments results in inadequate photoentrainment which is associated with degraded alertness and negative health effects. Recent research has shown that both the illuminance (i.e., perceived intensity) and wavelength of light affect photoentrainment. Simultaneously, modern lighting technologies have improved our ability to construct lights with desired wavelengths. To improve photoentrainment in low light environments, this research utilizes a multiple regression and multi-objective model to explore the relationship between the wavelength composition of artificial light and circadian stimulus (CS) for a fixed illuminance. The model is used to recommend emitter light intensity and wavelength characteristics that maximize CS in artificial lighting. These results suggest that by carefully choosing the center wavelengths for emitters we can achieve desirable CS values without increasing intensity. In addition, constraining the design to low illuminance values leads to increases in blue wavelength energy and shifts the color of illumination. Finally, constraining the design to a desirable range of colors reduces the size of this effect while still providing desirable levels of CS. The highest CS achieved at 250 lx is 0.669 without consideration for CRI or color difference. Constraining CRI and color to match D65, the maximum CS at 250 lx is 0.353 with a CRI of 91.1 and a color difference from D65 of 0.0094.

AFIT Designator


DTIC Accession Number