Aging Eyes with Yellowing Lens Linked to Sleepless Nights for Senior Citizens
Cataract could be factor in frequent insomnia among elderly; sleep quality has improved after cataract surgery
Sept. 1, 2011 - A natural age-related yellowing of the eye lens that absorbs blue light has been linked to sleep
disorders in a group of test volunteers, according to a study in the September 1 issue of the journal Sleep. As this type of lens
discoloration worsened with age, so did the risk of insomnia.
"The strong link between lens yellowing and age could help explain why sleep disorders become more frequent with
increasing age," said Line Kessel, M.D., Ph.D., the study's lead author.
In the Danish study, 970 volunteers had their eyes examined by lens autofluorometry, a non-invasive method for
determining how much blue light is transmitted into the retina.
Blue light is a portion of the visible-light spectrum that influences the normal sleep cycle by helping initiate the
release of melatonin in the brain. Melatonin is a hormone that helps signal to the body when it is time to be sleepy or alert.
Volunteers were considered to have a sleep disorder if they confirmed that they "often suffer from insomnia" or if they
purchased prescription sleeping pills within the last 12 months. Of those classified as having a sleep disturbance, 82.8 percent affirmed that
they both suffered from insomnia and used sleep medication.
Using this data, researchers calculated an inverse relationship between blue light transmission and the risk of having
sleep disturbances: the lower the blue light transmission into the retina due to a yellowing of the eye lens, the greater the risk of sleep
"The results showed that while age-related lens yellowing is of relatively little importance for visual function, it may
be responsible for insomnia in the elderly," said Kessel, a senior scientist in the Department of Opthalmology at Glostrup Hospital in
Significantly higher rates of sleep disorders were reported by older participants, women, smokers and those with diabetes
Previous studies have shown that the rate of lens aging is accelerated in smokers, patients with diabetes mellitus and
those at high risk for ischemic heart diseases. The Danish researchers addressed these factors in their statistical analyses.
"The association between blue light lens transmission and sleep disturbances remained significant even after we corrected
for age, sex, diabetes mellitus, smoking and the risk of ischemic heart disease," Kessel said.
She said another important factor to consider is that sleep quality has been shown to improve after cataract surgery.
"The transmission of blue light currently cannot be improved by any other method than cataract surgery. I´m involved with
another research project where we try non-invasively to remove the yellow color of the lens using a laser, but the method is not yet developed
for clinical use," Kessel said.
In the meantime, Kessel said it seemed prudent to recommend that physicians reconsider the prescription of sleeping
tablets in patients who have undergone cataract surgery.
This study was sponsored, in part, by The Danish Pharmaceutical Association and the healthcare company Novo Nordisk,
which specializes in diabetes care.
The monthly, peer-reviewed, scientific journal Sleep is published online by the Associated Professional Sleep Societies
LLC, a joint venture of the American Academy of Sleep Medicine and the Sleep Research Society. (www.aasmnet.org)
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