PROJECT SUMMARY. Sleep disturbances are common among persons with Alzheimer's disease and Related Dementias (ADRD) and their caregivers, often cited as the primary reason for institutionalization. Sleep disturbances are detrimental to quality of life for both members of the person with ADRD and caregiver dyad, and can be treated, especially when diagnosed appropriately and in a timely fashion. With no present cure, ADRD care models, clinical care teams, and research groups typically focus on measuring and improving quality of life and caregiver burden. However, both these outcomes can be negatively impacted by sleep and circadian rest/activity rhythm disturbances. The proposed pre-post study is nested within an NIA-funded Phase III randomized waitlist-controlled trial, Making Engagement Meaningful through Organized Routine Interaction (MEMORI Corps; PI Quincy Samus). The study evaluates the feasibility and efficacy of a 12-week, evidence-based intervention delivered by trained senior volunteers for 5 hours per week to community-living persons with ADRD. The parent study will deliver the intervention via a virtual, HIPAA-compliant video platform. Participants (n=240 dyads) will be randomly assigned to receive the MEMORI Corps intervention immediately (n=120 dyads) or following a 12-week delay (n=120 dyads). The proposed pre-post study will enroll 100 dyads from the delayed start (waitlist control) group, leveraging this postponed intervention start to collect baseline actigraphy data. Actigraphic data will be collected during the week prior to, and post intervention. The central hypothesis is that the intervention delivered by the parent study will improve sleep and circadian RARs of both ADRD and CGs and will be associated with the clinically significant outcomes; (a) Quality of Life and (b) caregiver burden. To test the central hypothesis, Ms. Antonsdottir will pursue the following Specific Aims: Aim 1: Determine whether nighttime sleep parameters [total sleep time, sleep efficiency, sleep onset latency, and wake after sleep onset] change pre-to-post (12 weeks) MEMORI Corps intervention implementation in (a) N= 100 ADRD and (b) N = 100 CGs. Aim 2: Determine whether changes in phase and strength of circadian RARs occur pre-to-post (12 weeks) MEMORI Corps intervention in (a) N=100 ADRD and (b) N=100 CG. Aim 3: Determine the association of change in ADRD and CG (i) sleep and (ii) circadian RARs following MEMORI Corps intervention with change in (a) QoL and (b) CG burden.