Mariana G. Figueiro, PhD, director of the Lighting Research Center at Rensselaer Polytechnic Institute in Troy, NY, and colleagues tested whether a tailored lighting system could help to improve sleep, mood, and behavior in people with Alzheimer’s disease in nursing homes.

“Given that light/dark patterns are a person’s primary cues to the current time, the constant dim light typically experienced by people living in residential care facilities may be an underlying cause of the sleep pattern disturbances so commonly found in this population,” Figueiro says in a release.

To test this hypothesis, over a 4-week period, lighting interventions were placed in areas where nursing home residents spent the majority of their waking hours and were left on from wake-up time until 6 pm. Forty-three residents (31 female, 12 male) participated in the short-term study, and 37 residents (25 female, 12 male) have completed the long-term study so far, all recruited from 10 nursing homes in the New York Capital District, Bennington, Vt, and South Bend, Ind.

Study participants experienced alternating periods of lighting that provided either high- or low-circadian stimulus for 4 weeks (short-term study) and 6 months (long-term study, successive four-week periods spaced by a four-week washout). The circadian stimulus (CS) metric, developed by the Lighting Research Center, characterizes a light source’s effectiveness for stimulating the circadian system as measured by its capacity for acutely suppressing the body’s production of the hormone melatonin (a well-established marker of the circadian system) after a one-hour exposure.

Both arms of the study used either a custom-designed LED light table or individual room lighting to deliver the intervention, depending on where the participants spent the majority of their time. Personal light meters were used to measure the light exposures received at the participants’ eyes. Sleep disturbance, mood, and agitation were also assessed using standardized questionnaires.

With the lighting intervention, researchers found that study participants who experienced the high-circadian stimulus showed significant decrease in sleep disturbance, depression, and agitation. Positive effects observed in the short-term study continued to improve over the long-term study.

The study, “Tailored Lighting Intervention to Improve Sleep, Mood and Behavior in Alzheimer’s Disease Patients,” was presented at the Alzheimer’s Association International Conference (AAIC) 2018 in Chicago.