Light measurement in the hospital: a comparison of two methods.

Disrupted sleep in hospitalized patients is widely reported, and ambient environmental lighting may be both a contributor to and a modifier of sleep/wake patterns. This is the first study to examine the congruence between two types of light meters, a wrist-worn device and a stand-alone device, and their respective light intensity measurements. The study sample included 20 light trials in 17 patients for a total of 480 paired light measurements. Descriptive data analysis indicated that both light meters dependably recorded changes in light levels, and Bland Altman plots demonstrated congruence between data from the two types of light meters. The results provide promising data on how to measure patient exposure to ambient light dependably in the continuously changing and unpredictable clinical setting.