June 5, 2009

Light may treat elder sleep problems

Blue light treatments may improve sleep quality in older adults, U.S. researchers found.

Researchers at the Rensselaer Polytechnic Institute in Troy, N.Y., tested whether a device used to deliver blue light directly to the eyes would affect circadian rhythms -- the body's internal clock that regulates when and how much people sleep and other biological cycles.

Light and dark patterns are the major synchronizer of circadian rhythms to the 24-hour solar day, study principal investigator Mariana Figueiro said in a statement. Light stimulus travels through the retina, the light-sensitive nerve tissue lining the back wall of the eye, to reach the master clock in the brain. However, a combination of age-related changes in the eye and a more sedentary lifestyle may reduce the amount of light stimulus reaching an older person's retina, therefore reducing the amount of light for the circadian system.

The device, designed by Topbulb. com, was worn by 11 subjects between the ages of 51-80. Each subject was exposed to two levels of blue light -- about 50 lux and 10 lux -- from the personal light-treatment device for 90 minutes on two separate nights.

Blood and saliva samples were collected at prescribed times to assess levels of nocturnal melatonin --a hormone used as a marker for the circadian clock.

The study found the blue light showed a stimulation effect on the circadian system.