Inclusion Criteria:  Participants must be diagnosed with amnestic mild cognitive impairment or mild Alzheimer's disease, as defined by a Montreal Cognitive Assessment (MoCA) score between 17 and 25 For the age-matched healthy controls, participants must not be diagnosed with mild cognitive impairment or Alzheimer's disease related dementias (MoCA score above 25). Participants must score a 5 or less in the Pittsburgh Sleep Quality Index (PSQI)  Exclusion Criteria:  All participants must not be taking sleeping medication or oral melatonin Presence of 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) residence in a skilled nursing facility or long-term care Major organ failure (e.g., kidney failure) Uncontrolled generalized disorders such as hypertension or diabetes Obstructing cataracts, macular degeneration, and blindness Severe sleep apnea or restless leg syndrome History of epilepsy