Our data suggest that modulating the characteristics of light carries the potential to modify the host response to injury and critical illness and thus, improve outcome. The ability to modify the host response to the stress of major operations and sepsis carries immense potential to improve patient care. The primary purpose of this study is to determine if exposure to bright blue (442nm) enriched light, by comparison to ambient white fluorescent light, reduces the inflammatory response or organ dysfunction in patients undergoing 1) medical treatment for pneumonia, 2) a 2-stage arthroplasty for surgical management of a septic joint, 3) surgery for a necrotizing soft tissue infection (NSTI), and 4) surgery for an intraabdominal infection (e.g., diverticulitis). We will expose participants to one of two (2) lighting conditions: 1) high illuminance (\ 1700 lux,), blue (442nm) spectrum enriched light and 2) ambient white fluorescent light that provides the standard environmental lighting (\ 300-400 lux, no predominant spectrum) of the hospital. Both cohorts will be exposed to a 12 hours:12 hours light:dark cycle photoperiod. Those subjects assigned to blue light will be asked to shine this small portable blue enriched light on themselves from 0800 to 2000 for 3 days. At the transition from light to dark, the blue-enriched light is turned off, and additional blue wavelength light removed with an amber filter. Thus, the total period of intervention is 72 hours. The outcome of interest is change in the inflammatory response after surgery for appendicitis or diverticulitis as measured by the following parameters: white blood cell count, heart rate, the development of abdominal abscess, serum cytokine concentrations. The outcome of interest is change in the inflammatory response during pneumonia as measured by the following parameters: white blood cell count, heart rate, and serum cytokine concentrations.