Researchers Develop Light-Treatment Device to Improve Sleep Quality in the Elderly
Studies report more than half of senior 65 years of age or older suffer from chronic sleep disturbances. Researchers have long believed that the sleep disturbances common among the elderly often result from a disruption of the body’s circadian rhythms—biological cycles that repeat approximately every 24 hours.
In recent years, scientists at the Lighting Research Center (LRC) and elsewhere have demonstrated that blue light is the most effective at stimulating the circadian system when combined with the appropriate light intensity, spatial distribution, timing, and duration. Researchers at the LRC have tested a goggle-like device designed to deliver blue light directly to the eyes to improve sleep quality in older adults.
As we age, the lens in the eye thickens and the pupil shrinks, reducing the amount of light passing through to the retina. In some cases, such as with persons with Alzheimer’s disease, the circadian system may require a stronger light stimulus due to deteriorating neural processes in the brain. These physical and neural changes can lead to muted signals to the circadian system. A marked increase in daytime lighting levels can counteract the age-dependent losses in retinal light exposure by providing a stronger signal to the circadian system. However, the color and intensity of commercially available lighting systems, like those used in senior residences, assisted-living facilities, and nursing homes, are designed for visual effectiveness and minimal energy use and not necessarily efficacious for generating light to stimulate the older circadian system.
Experiment and Results
In this project, the light-treatment prototype used in this study was developed by Topbulb.com, LLC, based on prior LRC light and health research. The device offers an alternative approach using specially designed goggles that deliver blue light spectrally tuned for optimum circadian response.
The device was worn by eleven subjects between the ages of 51 and 80 years of age. 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. The device was worn in the evening only for the purpose of demonstrating the stimulation effect.
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, with high levels at night when a person is in a dark environment and low levels during the day. However, if the personal light device was prescribed as a treatment, it would actually be worn at a more appropriate time earlier in the day.
After only one hour of light exposure, the light-induced nocturnal melatonin suppression level was about 35 percent for the low light level and about 60 percent for the high light level. In addition, the higher level of blue light suppressed nocturnal melatonin more quickly, to a greater extent over the course of the 90-minute exposure period, and was maintained after 60 minutes.
Having demonstrated its stimulation effect on the circadian system, the researchers believe the device could be subsequently used to increase sleep consolidation and efficiency in older subjects when worn for a prescribed duration at an appropriate time. The study also suggests that light goggles may be an effective way to deliver light treatment to those suffering from circadian sleep disorders.
Figueiro, Marianna; Bierman, Andrew; Bullough, John; Rea, Mark. 2009. A Personal Light-Treatment Device for Improving Sleep Quality in the Elderly: Dynamics of Nocturnal Melatonin Suppression at Two Exposure Levels. Chronobiology International, Volume 26 Issue 4, 726.
Sloane PD, Figueiro M, Cohen L. 2008. Light as Therapy for Sleep Disorders and Depression in Older Adults. Clinical Geriatrics, 16(3):25-31.
National Institute on Aging (1R41AG029693) through a Small Business Technology Transfer grant to Topbulb.com, LLC
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