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Alzheimer's Disease Health Center

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Bright Light Improves Dementia Symptoms

Study Shows Brighter Daytime Lighting Brings Improvement in Mood, Behavior
WebMD Health News
Reviewed by Louise Chang, MD

June 10, 2008 -- Turning up the lights during the daytime may boost mood and improve behavior in elderly adults with dementia, according to a new study.

Mood swings, sleep problems, and behavioral issues frequently affect those with dementia-related cognitive decline. Such disturbances can increase the person's risk of being admitted to an assisted living facility, according to background information in the journal article.

Environmental light affects the body's 24-hour biological clock, also known as the circadian rhythm. Too little light exposure can throw off the sensitive balance of the circadian timing system. Disturbances in circadian rhythm can lead to sleep woes. A hormone called melatonin also plays an important role in the maintaining the system's circadian rhythm.

Rixt F. Riemersma-van der Lek, MD, of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, and colleagues wanted to see how bright light with or without melatonin supplements would effect symptoms of dementia and sleep disturbances.

Their study is published in the June 11 issue of The Journal of the American Medical Association.

The study included 189 adults about 86 years old on average, mostly female, at 12 elder care facilities in the Netherlands. Most participants had dementia. Researchers randomly assigned the participants to a daily dose of melatonin or placebo (fake pill). The patients took the study medicine every night for an average of 15 months.

The facilities kept their lights on each day from about 9 a.m. to 6 p.m.; half of the facilities increased the intensity of their ceiling-mounted lights.

The researchers learned that bright light resulted in a modest improvement in dementia symptoms. Specifically, the use of bright daytime lighting:

  • Reduced cognitive decline on a mental status exam by a relative 5%.
  • Cut depression symptoms by a relative 19%.
  • Calmed slow increases in functional limitations by slightly more than half (53%).

Adding melatonin helped patients fall asleep about eight minutes faster and sleep longer by 27 minutes. The researchers recommend melatonin supplements only in combination with light. Melatonin combined with brighter lighting cut agitated behavior by 9%.

"The simple measure of increasing the illumination level in group care facilities [improved] symptoms of disturbed cognition, mood, behavior, functional abilities, and sleep," the researchers write. "The long-term application of whole-day bright light did not have adverse effects ... and could be considered for use in care facilities for elderly individuals with dementia."

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