Seeing Dementia in a New Light

For most of us, indoor light is an afterthought — a static background in our daily lives.

But new research from Arizona State University shows that what might be considered an afterthought could actually help people with dementia. In fact, making adjustments to that light during the day can help improve both the mood and nightly sleep for older adults with dementia.

“We often think about what we eat as shaping ourselves, right? But the light that we consume every day also significantly impacts our body,” says Nina Sharp, the study’s primary investigator and an assistant professor at The Design School at Arizona State University.

Sharp, who heads up the university’s DESmart Lab, and a team including her then-ASU colleague Jason Yeom studied 10 people with a median age of about 76 with dementia at Sunshine Village, a Phoenix memory-care facility, for seven weeks. Researchers used “biodynamic lighting”—which mimics daylight’s natural rhythms—to measure how it affected depression, agitation and sleep quality. The 2025 study was funded by the Arizona Alzheimer’s Consortium and Arizona State University Knowledge Enterprise. (Yeom has since left for Clemson University.)

Sharp says light brightness, color and spectrum can all significantly affect mood and cognitive performance. It can help with people’s internal clocks, telling them what time of day it is and allowing hormones to adjust for daily activities or sleep. “At each time of the day, we need different types of light—so exposure to constant lighting from morning to the evening is not healthy for us, because our need for lighting is dynamic,” Sharp says.

The use of biodynamic lighting at Sunshine Village increased participants’ sleep time by an average of 82 minutes — up from a baseline of 434 minutes. The study was published in the journal Geriatric Nursing.