Lighting tailored to the needs of an individual can improve sleep and reduce depression and agitation in persons with Alzheimer’s disease, according to a recent study led by Mariana Figueiro, light and health program director at the Lighting Research Center (LRC) at Rensselaer.

The study, published in the April 2016 Lighting Research & Technology journal, is the latest in a series of high-impact papers dating back to 2010, when Figueiro started conducting research funded by her first R01 grant from the National Institute on Aging.

Older adults in long-term care facilities often spend their days and nights in dimly lit rooms with minimal time spent outdoors. The constant, unvarying dim light found in many long-term care facilities means that older adults are not experiencing the robust daily patterns of light and dark that synchronize the body’s circadian clock to local sunrise and sunset. Disruption of this 24-hour rhythm of light and dark affects every one of our biological systems, from DNA repair in single cells to melatonin production by the pineal gland in the brain. Circadian disruption is most obviously linked with disruption of the sleep-wake cycle—feeling sleepy during the day and experiencing sleep problems such as insomnia at night—but is also linked with increased risk for diabetes, obesity, cardiovascular disease, and cancer.


The Lighting Research Center’s 24-hour lighting scheme demonstration room provides cycled electric lighting with cool, high light levels during the day and warm, low levels in the evening. Construction of the room was made possible by the Light & Health Alliance: Acuity Brands, Cree, GE Lighting, Ketra, OSRAM Sylvania, Philips Lighting, and USAI Lighting.

Sleep problems are all too common among older adults, especially those in long-term care facilities, yet sleep could not be more important to their overall health and well-being. In fact recent research has shown that poor sleep may directly impact the onset and progression of Alzheimer’s disease, and conversely, healthy sleep may prevent or slow progression of the disease.

In the new study, LRC researchers focused on a specific challenge: delivering light in a way that was highly effective for individuals with Alzheimer’s disease. To meet this challenge, the LRC developed a self-luminous light table to complement the custom-built overhead and ambient lighting systems used in the previous phase of the study.

“The light table is a key component of the tailored lighting system because it can deliver a strong dose of light at the eyes, which is important for stimulating the circadian system,” said Figueiro.

Today, many people think of light as just part of a building,” said Figueiro. “In the future, light will be more personalized and customizable, with the goal of improving human health and well-being.”—Mariana Figueiro

The first light table, installed at the Albany County Nursing Home in Albany, has garnered praise from caregivers and residents alike. The study was featured in the January issue of the American Psychological Association’s Monitor on Psychology magazine.

For the most recent phase of the study, now underway and enrolling new participants, the research team installed tailored lighting at several long-term care facilities throughout the U.S., including the MorningView Assisted Living Center in South Bend, Indiana. Staff members at MorningView have already seen improvements from the new lighting.

“Residents are now sleeping through the night. We have also seen a vast improvement in their mood,” said Dr. Suhayl Nasr, psychiatry medical director of Beacon Health System, who introduced the lighting project to MorningView Assisted Living Center.

Mariana Figueiro.

Mariana Figueiro.

The tailored light treatment provides cool, high light levels for high circadian stimulation during the daytime, delivering a circadian stimulus (CS) of 0.4. A CS of 0.4 translates to approximately 2000 lux at the cornea of 25,000 K (bluish white) light, similar to a blue sky on a clear day.

Results show that the tailored light treatment significantly improved sleep, significantly reduced depression, and significantly reduced agitation in Alzheimer’s patients. Both depression and agitation scores remained significantly lower after removal of the intervention, suggesting a beneficial carryover effect of the light.

Among the many positive outcomes of this project is the fact that the lighting principles and technologies utilized in these long-term care facilities can be transferred to benefit other populations: newborns in the NICU, students in schools, office workers, and eventually, the general public in their own homes.

“Today, many people think of light as just part of a building,” said Figueiro. “In the future, light will be more personalized and customizable, with the goal of improving human health and well-being.”