A Study to Compare Two Different Sleep Tests in Participants With No Symptoms or Early Symptoms of Alzheimer's Disease

Inclusion Criteria: * Have mild cognitive impairment, subjective memory complaints, or normal cognition. * Evidence of the presence of Alzheimer's pathology as measured by amyloid positron emission tomography (PET), cerebrospinal fluid biomarkers (amyloid beta and tau), or blood biomarkers. * Montreal Cognitive Assessment (MoCA) score of 24 or greater. * Clinical Dementia Rating Scale (CDR) global score of 0 or 0.5. * Able to provide signed informed consent. * On stable medications (including those for Alzheimer's disease) for 30 days before the first recording night of Study Period 1, and willing to remain on stable therapy during the study. * Must have a study partner who knows the participant well and can accompany the participant at visits where informant-rated scales are administered. Exclusion Criteria: * Severe illness that in the investigator's judgement would adversely affect the participant's participation in the study. * Skin illness that may interfere with study assessments. * Has a pacemaker or implantable cardioverter defibrillator. * Diagnosed with a sleep disorder. * Has irregular circadian patterns (works night shifts, etc.). * Is pregnant or lactating/breastfeeding at time of screening. * Use of sleep aid medications (such as melatonin, Ambien, Lunestra) or other medications or substances that could affect sleep (alcohol, cannabinoids, or opioids) on nights of in-clinic and at-home recordings. * Currently enrolled in another clinical study involving an investigational product or other type of medical research judged not to be scientifically or medically compatible with this study. * People who habitually spend less than 5 hours in bed per night. * No alcohol will be allowed at least 24 hours before the use of the EEG and throughout the clinical assessment period.