Characterizing Free-Living Light Exposure Using a Wrist-Worn Light Monitor

Abstract It was the purpose of this study to pilot the use of a new wrist-worn light monitoring device to document that indoor lighting for a particular day-shift work environment could serve as the primary light exposure dosage in healthy free-living humans. Twelve employees of a local hospital volunteered to wear a wrist-worn light monitor during all waking hours for an entire workweek (Monday—Friday). Light data were analyzed (3-Factor RM ANOVA) for the dose of light exposure (minutes of exposure x light intensity) within six light intensity categories (< 1, 1—100, 101—200, 201—500, 501—1000, > 1000 1x) relative to time spent within their work environment and all other time of the day. The greatest dose of exposure occurred within the 201—500 1x range during the subjects’ work shift. These data support the premise of others that long term exposure to dim indoor light intensities commonly experienced within a variety of work environments may serve as the primary entrainment factor for physiological and behavioral processes following a circadian rhythm.

Link to Abstract: http://www.ncbi.nlm.nih.gov/pubmed/12160339