This study aims to investigate the effect of a dynamic lighting intervention on sleep quality, circadian activity rhythms, and mood in older adults with dementia living in long-term care facilities. The dynamic lighting intervention is designed to create an ambient illumination that provides a high level of circadian stimulation in the morning and circadian-neutral lighting in the evenings through delivering varying light intensity and spectrum.

Light is the most important environmental element that is not only necessary to fulfill visual tasks but also is the main stimulus that regulates circadian rhythms. Daily exposure to proper lighting at the right time is reported as an effective non-pharmacological treatment to improve sleep disorders in various age groups including older adults. Several clinical studies have demonstrated the benefits of bright light therapy to improve sleep duration and sleep efficiency at night and reduce daytime sleepiness and behavioral disturbance (i.e., agitation, depression) in older adults. In most of these studies, lighting intervention includes a lightbox that exposes participants to an extra lighting source with specific characteristics (i.e., blue-enriched bright light) for only a few hours without considering the impacts of other lighting sources that individuals are exposed to throughout the day. A significant impediment to administrating bright light therapy for older adults with dementia is that these individuals typically require reminders to remain seated and awake in front of a lightbox long enough to benefit from the bright light exposure. An alternative way to deliver bright light is through providing circadian-effective ambient lighting. The circadian system responds best to high-intensity short-wavelength light (peak wavelength of 480 nm). However, the lighting design in long-term care facilities does not necessarily provide adequate intensity and spectrum to stimulate circadian rhythms in elder residences. Studies reported poor lighting conditions in nursing homes. According to these studies, daytime lighting in these institutions is not even sufficient to fulfill older adults' visual needs, while light at night is relatively often excessive. Thus, this study will be carried out to achieve the following aims:

Aim1: Investigate the effect of a dynamic lighting condition on circadian activity rhythms and selected sleep parameters in older adults with dementia.

Aim2: Evaluate the effect of a dynamic lighting condition on mood.

Findings from this study will provide initial guidance to the designers and administration of memory care facilities as to the lighting design recommendations of greatest benefits to the sleep, mood, and well-being of institutionalized older adults diagnosed with dementia.

The participants will be recruited from two memory care facilities from the greater Phoenix area, based on the recommendation of the managers at the memory care facilities.

Environment: In this study, the human-lighting interaction will occur in the common areas of the selected memory care facilities where older adults with dementia spend most of the daytime hours under the supervision of facility caregivers. Research personnel will install experimental luminaires in the memory care facility's common area. During this visit, research personnel will also give a number of actigraphs and light trackers (which will be used for data collection throughout the study) to caregivers and instruct them on how to use these devices on participants. Participants will also be instructed (by caregivers) on how to use each device.

Week 1 (Baseline): Patterns of sleep, moods, and light exposure will be monitored ad libitum for one week. The experimental luminaires will remain off during Week 1. Placing luminaires in the common area of the facility prior to the use of lighting interventions during Weeks 2 to 7 will minimize environmental variations between baseline and intervention measurements (e.g., new luminaires in the room) and decrease the bias resulting from the Hawthorne effect on collected data.

Weeks 2-7 (Intervention): The intervention period will start right after the baseline and continue for six constructive weeks. There are two lighting interventions, each of which is three weeks long. We will randomly assign one of the residences to start with (Dynamic > Placebo) lighting intervention while the other start with (Placebo > Dynamic) lighting intervention. Actigraphy will be conducted only on the last 7 days of each condition. Light spectrum and intensity will be tracked continuously throughout the waking hours (Blue Iris mobile sensor). Moreover, caregivers will complete CSDD and CMAI every seven days to assess the short and long-term effects of each condition on mood and agitation of older adult participants.

Inclusion Criteria:

• Aged over 50.
• Diagnosed with mild to major dementia based on the physician and care facility manager's recommendation.
• Has no major organ failure, major diagnosis other than dementia, history of head injury, obstructing cataracts, macular degeneration, and blindness based on their Medical history.
• Not taking light therapy
• Female or male
• No current or planned use of light-altering devices (e.g., blue-blocking and/or tinted glasses and contact lenses)

Inclusion Criteria:

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No individual participant data will be shared. Results will be published by the investigators in academic journals and conference proceedings. However, neither the name nor identity of the participants will be used in any publications. Sharing of generated study data will be carried out in several different ways. We plan to make our results available to researchers and potential collaborators interested in human-light interactions.

The data will be available after the data collection and analysis is complete which is anticipated to be in January 2024. The findings will be published in academic journals

Neither participants nor their caregivers will be told about the structure of the lighting conditions and the potential effects, just that the lighting could change daily.