ZircLight: Spectrum-Specific Lighting for Shift Work Epidemiologic evidence has established that shift work exposure is associated with an array of adverse health consequences, including increased risk of cardiovascular disease, gastrointestinal disease, and cancer. Investigations of the mechanisms linking shift work and disease have highlighted the importance of nocturnal light exposure and the consequent chronic disruption of circadian organization. Recent evidence that light input to the circadian system is mediated by neural systems distinct, anatomically and functionally, from those involved in vision provides a theoretical foundation for addressing this pathophysiology in shift workers. Recent work has demonstrated that the use of filtering lenses to eliminate the deep blue end of the visual spectrum (<480nm) significantly improves nocturnal alertness and performance, and normalizes endocrine and genetic indices of circadian organization. This Phase I SBIR application seeks to build on this initial finding by developing spectrum-specific, indoor LED lighting solutions that provide usable indoor illumination absent the spectral components that are associated with circadian disruption. Indoor lighting that could be used at night without producing circadian disruption, providing the potential for immediate improvements in alertness and performance and long-term improvements in shift worker health, would have significant potential application in the large and growing segment of the modern economy that requires night work. This Phase I SBIR project will address two specific aims in anticipation of Phase II clinical testing. 1) We will construct prototype fixtures using LEDs with a notch filter that eliminates the implicated blue (460-480nm) band;and 2) we will test whether illumination to normal indoor work intensities can be achieved without disrupting an index of normal circadian organization (i.e. melatonin secretion), using an overnight laboratory study protocol with test subjects. Based on the results of this initial effort, planned Phase II studies will examine the impact of spectrum-specific lighting in real shift work settings using additional outcome measures of performance and health.

Public Health Relevance

This is a Phase I SBIR application seeking support for the development of filtered LED bulbs for use in shift work settings. Epidemiological research suggests that light exposure during the night hours on a shift work schedule has significant adverse impact on the health of the shift worker. The disruption in internal timing caused by nocturnal light is associated with an increase in the risk of heart disease, obesity and certain kinds of cancer. More recently, it has been shown that the harmful effects of the light may be due to a small component of the blue light fraction of the visual spectrum. By filtering this component out of the light used to illuminate shift work settings, the harmful effects of shift work may be reduced. Studies in simulated shift work suggest that filtering out the blue light component results in normalization of the rhythms in hormone secretion (melatonin and cortisol) and increases in alertness and vigilance performance during the night work hours. ZircLight is seeking SBIR support for the development and testing of LED bulbs with attached filters to remove the deleterious portion of the visual spectrum. These bulbs would be used in shift work settings such as hospitals and factories to provide illumination without the blue component. If successful, this project could provide substantial health benefits for millions of US workers who are required to work the night shift.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Small Business Innovation Research Grants (SBIR) - Phase I (R43)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-ETTN-K (10))
Program Officer
Twery, Michael
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Circadian Management, Inc.
United States
Zip Code