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The results of a recent pilot study by LRC researchers has found that Alzheimer's patients sleep better through the night when they are first exposed to blue LED lighting a few hours before going to bed. Mariana Figueiro led the team conducting the study.

"Light regulates circadian system in healthy humans," said Figueiro. The circadian system, which controls the sleep-wake cycle, is composed of rhythms that repeat about every 24 hours. "The body's temperature is typically high during the day, which allows people to remain alert and active. At night, the temperature is lower, which facilitates sleep."

People with Alzheimer's disease, according to Figueiro, often wake up repeatedly through the night, causing them to fall asleep more often during the day. One of the most serious results is nighttime wandering, which is often the reason Alzheimer's patients are institutionalized.

Figueiro's team conducted the 30-day light study at the Schuyler Ridge Residential and Adult Day Health Care Center in Clifton Park. The team chose blue LEDs (light-emitting diodes) because recent research has shown that short wavelength (blue) light is most effective at affecting the circadian system. Middle wavelengths (yellow-green) are better for visual performance.

Four Alzheimer's patients were exposed to about 20 watts of blue LED lighting two hours before bedtime, from 6 - 8 p.m., for two 10-day periods. Red LEDs were used as a control for placebo effects. The team found that blue light exposure delayed the decline of the patients' body temperatures by two hours, helping them to sleep better between two and four hours after the light exposure. Two patients who wore wrist activity monitors showed more activity during daylight than at night. To confirm these findings, the LRC plans to replicate this study in a larger population.

An article about the study is being published in the journal, Sleep Review. For more information, contact Mariana Figueiro at 518-687-7142 or email figuem@rpi.edu