A goggle-like device designed to deliver blue light directly to the eyes to improve sleep quality in older adults suffering from chronic sleep disturbances has been developed by scientists from Lighting Research Centre (LRC).
Sleep disturbances increases with age. 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.
It has been shown that blue light is the most effective at stimulating the circadian system when combined with the appropriate light intensity, spatial distribution, timing, and duration.
"Light and dark patterns are the major synchronizer of circadian rhythms to the 24-hour solar day," said Dr Mariana Figueiro, Lighting Research Center Light and Health Program director and principal investigator on the project.
"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," the expert said.
"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," she added.
The light-treatment prototype was developed by Topbulb.com, LLC, based on prior LRC light and health research.
It offers an alternative approach using specially designed goggles that deliver blue light spectrally tuned for optimum circadian response.
During the study, the device was worn by eleven subjects between the ages of 51 and 80 years of age, who were exposed to two levels of blue light for 90 minutes on two separate nights.
The researchers collected the blood and saliva samples and assessed 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.
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.
The researchers believe that 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 suggests that the light goggles might be a practical, comfortable, and effective way to deliver light treatment to those suffering from circadian sleep disorders," said Figueiro.
The study appears in Chronobiology International.