Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Graduate Nursing


The lives of persons with severe and persistent mental illness (SPMI) are often plagued by recurring or unrelenting negative symptomotology affecting their mood and behavior. The literature supports the influence environmental light can have on the mood and behaviors in susceptible persons. The purpose of this pilot study was to determine the degree of environmental light experienced by a control group of non-SPMI persons as compared to a comparison group of persons with SPMI. The study consisted of two groups with seven control and seven comparison group members. The study matched one control and one comparison group member for each 48 hour period of study. Group members each wore a Sleepwatch-L on their non-dominant wrist during the 48 hour study. The device measured lux variables and stored the data until downloaded onto a computer via an interface unit. The data was saved and later statistically analyzed. The sample in this study was small. No statistically significant (p:S.05) difference in environmental light exposure was determined between the control and comparison group in this pilot study. However, interesting differences in means of lux variables did occur between groups. These differences in means could serve as a basis for future research.

Library of Congress Subject Headings

Mental illness -- Phototherapy



Number of Pages



South Dakota State University