[tabi] FW: [BlindGeekZone] Optic nerve Disease and Insomnia

  • From: "Joe Plummer" <joeplummer@xxxxxxx>
  • To: <tabi@xxxxxxxxxxxxx>
  • Date: Sat, 22 Jan 2011 20:09:02 -0500


Joe Plummer (JP)
-----Original Message-----
From: blindgeekzone@xxxxxxxxxxxxxxx [mailto:blindgeekzone@xxxxxxxxxxxxxxx]
On Behalf Of Jean
Sent: Saturday, January 22, 2011 2:38 PM
To: blindgeekzone@xxxxxxxxxxxxxxx
Subject: [BlindGeekZone] Optic nerve Disease and Insomnia


I belong to a chat list where we started discussing insomnia and blindness.
By using Google, I found this information. I do have a lot of trouble
sleeping and am now totally blind. I've had glaucoma with probable nerve
damage since I was five months old but had no trouble sleeping or staying
awake during the daytime until I lost most of my sight.

Jean . 

In the February issue of the journal Ophthalmology, the investigators report
on a study involving 25 students, ages 12 to 20, from the Missouri School
for the Blind and 12 students with normal sight from the Thomas Jefferson
School, a boarding school in suburban St. Louis. The visually impaired
students were divided into two groups: Those whose visual problems were
related to optic nerve disease and those whose vision loss did not involve
the optic nerve. The optic nerve is made up of ganglion cells, the type of
cells targeted by eye diseases such as glaucoma. 

Participants with optic nerve disease were 20 times more likely to be
pathologically sleepy (napping 20 or more minutes per day) than those with
normal sight. They also were nine times more likely to have pathologic
sleepiness than children who were blind from non-optic nerve diseases. 

"We suspect these patients have difficulty using daylight to synchronize
their internal rhythms to the outside world," says senior investigator
Russell N. Van Gelder, M.D., Ph.D., assistant professor of ophthalmology and
visual sciences and of molecular biology and pharmacology at the School of

In recent research, Van Gelder found that the retina contains not only the
photoreceptor cells called rods and cones, which translate light into
vision, but it also houses non-visual photoreceptor cells called
intrinsically photosensitive retinal ganglion cells (ipRG cells) that
function as the eye's "light meter." 

In a camera, the light meter helps a photographer determine how to set the
shutter speed and whether to use a flash. By determining light levels, ipRG
cells help synchronize the body's sleep/wake cycle, reset the internal body
clock, control the pupil of the eye's response to light and regulate the
release of hormones such as melatonin. These ipRG cells continue to gather
and use information about light even in animals that otherwise are visually

"In our basic research, we have demonstrated that animals that lack rods and
cones in the retina still have very normal circadian, or body clock,
functions," he says. "But animals that lack the ganglion, or 'light meter'
cells cannot synchronize their clocks to the outside world." 

The ipRG cells that act as the eye's light meter are concentrated together
at the head of the optic nerve, so Van Gelder's team wondered whether
children with optic nerve disease might have problems regulating their
internal body clocks. To measure the impact of the loss of those cells,
first author Raymond Wee, a graduate student in Van Gelder's laboratory, had
participants wear a device known as a wrist-worn actigraph. Worn like a
watch, the actigraph measures every movement a person makes. A sophisticated
computer algorithm then uses this movement information to determine whether
a person was awake or asleep, active or inactive. Children in the study wore
the actigraphs every day for two weeks. 

Those with optic nerve disease had highly variable wake-up times and also
had trouble falling asleep, compared to blind children without optic nerve
damage and sighted children. Those sleep problems led them to nap more
frequently, and children with optic nerve disease napped, on average, about
28 minutes a day. 

None of the children in the study had any other conditions that might
contribute to sleep disorders. None took sedative drugs, had
attention-deficit hyperactivity disorder (ADHD) or were being treated with
stimulant medications. So, the researchers believe the sleep problems these
children experienced were directly related to their eye disease. 

"Taken together, these results lead to the unexpected conclusion that eye
disease can be a risk factor for sleep disorders, and the health of the
optic nerve strongly influences risk," Van Gelder says. 

In future studies, Van Gelder hopes to test whether treatment with melatonin
helps regulate sleep patterns in children with optic nerve disease.
Melatonin is a naturally occurring hormone that helps regulate the circadian
clock. Its release is related to the eye's light meter function. 

But even before he learns whether it's possible to help these patients to
synchronize their internal clocks to the outside world, Van Gelder believes
it is important for health professionals to begin considering the impact of
eye disease on sleep. 

"Physicians and other health-care professionals should be sensitive to the
possibility of daytime sleepiness or insomnia, particularly in patients with
severe optic nerve disease," Van Gelder says. "Your eye doctor might want to
make a point of asking how you've been sleeping." 

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