Background: This methodological case study describes light exposure and rest-activity patterns in an older adult with dementia and his caregiver spouse. Methods: Two devices were used to measure rest-activity and light exposure data: a wrist-worn actigraph with a light sensor to record full spectrum light exposure data and an eye-level wavelength-sensitive light meter (Daysimeter). The wife wore both devices simultaneously; the husband wore only the actigraph. Results: There were minimal feasibility issues in using the devices in the home setting. The wife's light exposure was considerably better than her husband's, but she spent little time in bright lighting. Her circadian stimulus (CS) and rest-activity values suggest a high level of circadian disruption. Conclusion: This case study provides beginning support for the use of the Daysimeter in the home setting while also highlighting unrecognized circadian disturbances and very low light levels in an older couple's home.