Researchers studied 189 residents in 12 assisted-care facilities, most of whom had dementia. Some residents received doses of bright light between 9 a.m. and 6 p.m., some took supplements of melatonin or placebo pills, and some received both treatments. A fourth group received no treatment. Almost all of the participants completed at least a year of the study.
People in the facilities with bright daytime lighting appeared to have less progression in their dementia. They had 53% less of a decline in physical function scores, and 5% less decline in memory test scores, compared with the average decline at dimly lit facilities. Patients exposed to bright light were also 19% less likely to develop depression during the time of the study.
People who took melatonin without bright light frequently complained of depression and were more likely to become socially isolated. This suggests that melatonin alone is not useful. However, when melatonin and bright light exposure were combined, depression rates were not higher than expected, and after several months of use, sleeping patterns seemed to improve. There was longer uninterrupted sleep, less frequent episodes in which residents were up out of bed at night, and somewhat less agitated behavior, according to researchers, who reported their findings in Journal of the American Medical Association (JAMA) in 2008.
For people with dementia and for their caregivers, the use of bright lights is a simple, safe change. It may be helpful to combine light therapy with melatonin for people who have difficulty getting to sleep or staying asleep. These findings could improve the quality of life for people with dementia and ease strain on those who care for them.