To investigate the impact of a long-term light treatment intervention on sleep physiology and memory in mild cognitively impaired and mild Alzheimer's disease patients living at home. The goal is also to measure the impact of the lighting intervention on caregivers' sleep, cognition, depression, and quality of life.

The current application proposes to investigate the impact of a long-term light treatment intervention on sleep physiology and sleep-dependent cognitive processes in mild cognitive impairment (MCI) and mild Alzheimer's disease (AD) patients. The premise is that older adults, especially those with cognitive impairment, are often in continuous dim light, which leads to circadian misalignment. Circadian misalignment impacts the close relationship between homeostatic and circadian processes, which can reduce memory-related sleep features. The hypothesis is that a lighting intervention technology (LIT), designed to promote circadian entrainment, will improve sleep by aligning the two sleep processes (circadian and homeostatic) and, thus improve cognition. In addition to improving patients' lives, LIT has the potential to reduce the overnight burden on caregivers. Thus, an exploratory goal is to also measure the impact of LIT on caregivers' sleep, cognition, depression, and quality of life.

Inclusion Criteria for MCI/Mild AD Participant:

• Subject has diagnosis of amnestic mild cognitive impairment (MCI) or mild Alzheimer's disease (AD), as defined by a Montreal Cognitive Assessment (MoCA) score between 17 and 24 and those who fall between 0.5-4.0 and 4.5-9.0 in the Clinical Dementia Rating Scale Sum of Boxes (CDR-SOB) instrument
• Subject has sleep disturbance indicated by a score >5 on the Pittsburgh Sleep Quality Index and sleep efficiency below 80% as indicated via actigraphy
• Subject resides in his/her home, independent living, or assisted living facilities with a caregiver.

Exclusion Criteria for MCI/Mild AD Participant:

• Subject diagnosed with another brain disease that fully explains the dementia (extensive brain vascular disease, Parkinson's disease, dementia with Lewy bodies, traumatic brain injury, or multiple sclerosis)
• Subject resides in a skilled nursing facility or long-term care
• Subject has had recent changes in psychotropics (14 days)
• Subject has major organ failure (e.g., kidney failure)
• Subject has uncontrolled generalized disorders such as hypertension or diabetes
• Subject has obstructing cataracts, macular degeneration, and/or blindness
• Subject has undergone cataract surgery and received an intraocular lens coated with ultraviolet- and blue-blocking filters (400-440/440-500 nm)
• Subject diagnosed with severe sleep apnea; using the Sleep Apnea scale of the Sleep Disorders Questionnaire (SA-SDQ) the study will use a score of 29 as a cutoff for men and a cutoff of 26 for women
• Subject diagnosed with restless leg syndrome (RLS); using the International Restless Legs Scale (IRLS), the study will use a cutoff of ≥11 as a positive screen for RLS
• Subject has a history of severe photosensitivity dermatitis, severe progressive retinal disease (e.g., macular degeneration), or a permanently dilated pupil (e.g., after certain types of cataract surgery)

For caregivers, we will accept those who:

• Live with the patients
• Are not diagnosed with dementia (MOCA between 25 and 30 and CDR=0)
• Understand English
• Are willing to help with the study
• No other inclusion/exclusion criteria will be used for enrolling caregivers. There is no age requirement for caregivers.