Phase 2 - Rhythmic Light Therapy for Alzheimer's Disease Patients

Phase 2 - The Use of Rhythmic Light Therapy to Entrain Gamma Oscillations and the Circadian System in Patients With Alzheimer's Disease

Participants will randomly be placed into one of four groups and experience one of the four following conditions: (1) a placebo light that provides a 40 hertz (Hz) flicker (rhythmic light [RL]); (2) a placebo light with a random flicker (placebo condition for rhythmic light); (3) a light source that will stimulate the circadian system and provides a 40 Hz flicker (RL); or (4) a light source that will stimulate the circadian system and provides a random flicker (placebo condition for rhythmic light). Following a baseline week, participants will experience his/her assigned lighting condition for two hours in the morning for 8 weeks. After a 4-week washout period, a final round of assessments will be obtained. Study assessments (except for the Pittsburgh Sleep Quality Index and Montreal Cognitive Assessment) will be collected at the end of each week, for a total of 8 assessments.

The tailored lighting intervention used to promote circadian entrainment will provide high circadian stimulation during the day produced by narrowband blue light peaking at 470 nanometers (nm). A comparison lighting intervention (i.e., placebo lighting), a narrowband red light peaking at 630 nm, will be used as a control. Both the red and the blue light devices will also provide either the 40 hertz (Hz) flicker (RL) or the random flicker (placebo RL). For the random flicker (placebo RL), the duty cycle will be delivered with a random interval determined by a Poisson process with an average interval of 40 hertz (Hz).

Inclusion Criteria:

• Participants must be diagnosed with mild cognitive impairment or mild Alzheimer's disease, as defined by a Montreal Cognitive Assessment score between 17 and 25;
• Have sleep disturbance indicated by a score >5 on the Pittsburgh Sleep Quality Index
• Participants must reside in their homes, independent living, or assisted living facilities

Exclusion Criteria:

• Participants taking sleep medication
• Residence in a skilled nursing facility or long-term care
• Obstructing cataracts, macular degeneration, and blindness
• Severe sleep apnea or restless leg syndrome
• History of severe epilepsy