Tailored Lighting Intervention for Persons with Dementia and Caregivers Living at Home

Abstract

Objectives: Light therapy has shown promise as a nonpharmacological treatment to help regulate abnormal sleep-wake patterns and associated behavioral issues prevalent among individuals diagnosed with Alzheimer's disease and related dementia (ADRD). The present study investigated the effectiveness of a lighting intervention designed to increase circadian stimulation during the day using light sources that have high short-wavelength content and high light output.

Methods: Thirty-five persons with ADRD and 34 caregivers completed the 11-week study. During week 1, subjective questionnaires were administered to the study participants. During week 2, baseline data were collected using Daysimeters and actigraphs. Researchers installed the lighting during week 3, followed by 4 weeks of the tailored lighting intervention. During the last week of the lighting intervention, Daysimeter, actigraph and questionnaire data were again collected. Three weeks after the lighting intervention was removed, a third data collection (post-intervention assessment) was performed.

Results: The lighting intervention significantly increased circadian entrainment, as measured by phasor magnitude and sleep efficiency, as measured by actigraphy data, and significantly reduced symptoms of depression in the participants with ADRD. The caregivers also exhibited an increase in circadian entrainment during the lighting intervention; a seasonal effect of greater sleep efficiency and longer sleep duration was also found for caregivers.

Conclusions: An ambient lighting intervention designed to increase daytime circadian stimulation can be used to increase sleep efficiency in persons with ADRD and their caregivers, and may also be effective for other populations such as healthy older adults with sleep problems, adolescents, and veterans with traumatic brain injury.

Keywords: ADRD; Alzheimer’s disease; circadian rhythms; dementia; depression; light therapy; short-wavelength light; sleep.

Figures

Figure 1

Relative spectral power distribution of the light source used during the intervention period

Figure 2

Schematic of a dining room with tailored lighting intervention

Figure 3

Experimental data collection timeline

Figure 4

Circadian stimulus (CS) rose significantly for both the participants with ADRD and the caregivers during the intervention phase. As expected, it fell to near baseline levels after the intervention ceased. Error bars represent standard error of the mean. *= statistical significance

Figure 5

Phasor magnitude was significantly affected for both the participants with ADRD and the caregivers. Error bars represent standard error of the mean. * = statistical significance

Figure 6

Interdaily stability (IS) fell and rose significantly over the course of the study for the caregivers, but not for the participants with ADRD. Error bars represent standard error of the mean. * = statistical significance

Figure 7

Caregivers slept significantly longer in the winter than in the summer, averaged over all phases of the study. Error bars represent standard error of the mean. * = statistical significance

Figure 8

For the participants with ADRD, sleep efficiency showed a slight rise, as expected, during the intervention phase. Error bars represent standard error of the mean. * = statistical significance

Figure 9

Sleep efficiency increased significantly for caregivers from summer to winter. Error bars represent standard error of the mean. * = statistical significance

Figure 10

The Geriatric Depression Scale scores of the participants with ADRD fell over the course of the study, indicating less depression. The difference between baseline and post-intervention was significant. Error bars represent standard error of the mean. * = statistical significance