Light treatment tailored to increase circadian stimulation during the day may improve sleep, depression and agitation in people with Alzheimer's disease and related dementia, according to a recent study.

Researchers found that exposure to the tailored light treatment during daytime hours for four weeks significantly increased sleep quality, efficiency and total sleep duration. It also reduced scores for depression and agitation.

Alzheimer's disease is the most common form of dementia among older adults, affecting as many as five million Americans, according to the Center for Disease Control and Prevention.

"It is a simple, inexpensive, non-pharmacological treatment to improve sleep and behavior in Alzheimer's disease and dementia patients," Mariana Figueiro, principal investigator and an associate professor and Light and Health program director of the Lighting Research Center at Rensselaer Polytechnic Institute in Troy, N.Y., said in a statement. "The improvements we saw in agitation and depression were very impressive."

For the study, researchers collected data from 14 nursing home patients with Alzheimer's disease and related dementia. A light source producing low levels of 300 to 400 lux of a bluish-white light with a color temperature of more than 9000 K was installed in the residents' rooms. Light exposure occurred during daytime hours for a period of four weeks. Light-dark and activity-rest patterns were collected using a calibrated instrument prior to and after the lighting intervention. Measures of sleep quality, depression and agitation also were collected using standardized questionnaires.

Figueiro said the improvement in sleep quality also was associated with other noticeable behavioral changes.

"Subjective reports by the nursing staff were that the patients were calmer, eating better and their overall behavior was more manageable," she said.

The findings were recently published in an online supplement of the journal Sleep.