Disturbed night-time sleep is common in older persons with Alzheimer's disease and related dementias (ADRD), leading to significant negative effects on the daytime function of the affected person and on the well-being of caregivers. Sedating drugs, the conventional treatment for disturbed sleep, have limited effectiveness and pose increased risk in this population. Disturbed sleep in ADRD is virtually always accompanied by marked disturbances of the circadian system, and research has established that controlled bright-dark light cycles will synchronize that system to the 24-hour solar day. Clinical trials of light therapy in unselected nursing home residents with ADRD have identified statistically significant but modest effects on sleep;however, most have used treatment systems that are inefficient and poorly tolerated. Taking advantage of recent findings from basic research on photobiology and the lessons learned from clinical trials to date, this phase 2 clinical trial will evaluate the efficacy, tolerability, and safety of a novel, refined method of delivering light as therapy to persons with ADRD who have disturbed sleep. Among the innovations in this method are: a) use of newly available, narrow band (peak ? = 460 nm) light sources that will provide greater circadian stimulation at lower levels of visual brightness;b) use of a novel delivery system that will allow the treatment to be applied to living spaces instead of requiring subjects to sit in front of light panels;c) restriction of the study to persons with ADRD who have disturbed sleep and do not have a primary sleep disorder requiring specialty care;and d) application to the home setting, with assessment of the impact of the intervention on family caregivers. The trial will enroll and study 18 persons, each of whom will receive 6 weeks of the intervention and 6 weeks of a low circadian-stimulating red light control condition. Primary outcomes will be sleep latency, duration and efficiency, measured by wrist actigraphy, and burden and caregiving hassles reported by family caregivers. The study will also determine the acceptability of the intervention to participants, the prevalence of potential adverse effects, and will measure, using a novel circadian light meter, the amount of circadian and visual stimulation achieved at participant eye level. The study team consists of an interdisciplinary group of scientists from a leading long-term care research center and a nationally-prominent lighting research center. The proposed lighting scheme is practical, does not restrict movement, and could be replicated at modest cost. Therefore, if the proposed preliminary study were successful and subsequent larger trials confirmatory, such a treatment could improve the health, well-being, and safety of several million elderly who have dementia and clinically significant circadian-related sleep disorders, and also benefit their caregivers. PUBLIC HEALTH RELEVANCE: Approximately five million persons in the U.S.A. currently suffer from Alzheimer's Disease and Related Disorders (ADRD), and that number is anticipated to grow to between 12 and 14 million by 2050. Sleep disturbances affect the majority, leading to further functional impairment and a risk of early institutionalization, as well as having negative impact on the mental health, sleep patterns, and physical health of family caregivers. Existing treatments are relatively ineffective and are associated with a high risk of adverse events. Therefore, improved treatment of sleep problems in persons with ADRD would improve health outcomes of both the person with the disease and of family caregiver, and has the potential to reduce overall health care expenditures and delay nursing home placement for this large and growing patient population.