Alzheimer's Light Therapy & Melatonin

Alterations in biological rhythms affect 25 percent of Alzheimer's patients, according to a review by Dawit A. Weldemichael and George T. Grossberg in the September 2, 2010 edition of "International Journal of Alzheimer's Disease." Degradations in the nervous and endocrine systems mediate these changes as the hypothalamus and pineal gland control the timing of daily cycles. Treatment using light and melatonin changes these internal clocks and improves the symptoms of Alzheimer's disease.

Twilight Simulation

People with Alzheimer's disease often live in nursing homes with inadequate lighting. Losing contact with the natural light-dark cycle can adversely affect biological clocks. A report by Paola Fontana Gasio and co-workers in the January 2003 issue of "Experimental Gerontology" looked at the impact of twilight simulation. These researchers exposed patients with dementia to a portable light system reflecting the natural light-dark cycle. The subjects received either the twilight simulation or an inert treatment for three weeks. The active treatment changed the timing of the patients' sleep-wake cycle. Relative to controls, the demented subjects went to bed earlier during twilight simulation. The patients also fell asleep quicker, slept longer and had less sleep disruptions.

Light Therapy

Giving Alzheimer's patients brief pulses of bright light can improve their biological rhythms as well. A study by Glenna A. Dowling and associates described in the June 2005 edition of "International Psychogeriatrics" evaluated phototherapy in people with severe Alzheimer's. The scientists exposed patients to an hour of unusually bright light in the morning for 10 weeks. They exposed controls to normal room lighting. Bright light improved the subjects' daily activity-rest rhythm, and ambient light had no effect. The phototherapy also improved the patients' sleep quality. The results, however, were inconsistent as only the most severe patients benefited.

Melatonin Intake

Melatonin, like light, can affect the timing of behavioral rhythms, and melatonin-induced changes can improve the symptoms of dementia. A paper by Jiska Cohen-Mansfield and colleagues in the August 1, 2000 issue of "Archives of Gerontology and Geriatrics" tested exogenous melatonin in demented patients experiencing sundowning. The latter form of agitation and confusion appears at sunset in people with dementia. Nightly melatonin use decreased sundowning. In fact, the patients were less agitated and confused across the entire 24-hour period after taking melatonin. They also felt more alert during the day and tended to sleep better at night.

Treatment Combination

Light and melatonin affect biological rhythms, and each helps treat the dementia seen in Alzheimer's patients. Doctors can combine these two treatments and achieve more robust effects. Another clinical trial by Dowling and her team in California tested institutionalized patients with dementia for 10 weeks. Alzheimer's patients received either morning light or morning light combined with evening melatonin. Control subjects received only ambient lighting. The results, published in the February 2008 edition of "Journal of the American Geriatrics Society," indicated that light alone did not have an effect. The light-melatonin combination, however, enhanced the patients' activity-rest rhythm. The subjects were more active during the daytime hours.