LIGHT THERAPY
for a
BLUE PLANET AND BEYOND
Few treatments have emerged in psychiatry
that have relatively few side effects, are of
minimal cost and alleviate symptoms in less
than a week. Fortunately for people who suffer
from clinical seasonal affective disorder, or
SAD, light therapy is one of those rare treat-
ments. "It's striking, in the world of psychiatry,
how quickly light works as a therapeutic stim-
ulus compared to pharmacological treatments,
which may take several weeks to provide
relief," says George Brainard, PhD, neurology
professor and director of Jefferson's Light
Research Program.
During fall and winter, 14 percent of the
U.S. population experiences some sub-clin-
ical symptoms of SAD, a type of depression;
these symptoms sometimes include mild
weight gain, modest increased need for sleep,
tendency to be less socially interactive and
generally feeling worse during the short days
of late fall and winter. But for an estimated
2 percent of the population, symptoms can
be severe and debilitating and may include
feelings of hopelessness and weakness or
thoughts of suicide.
Bear-like Behavior
As its name implies, SAD is different from
typical depression in that its symptoms recur
annually in the fall and winter. People with
SAD also tend to crave carbohydrates and
may gain 10 to 30 pounds during the darkest
months of the year, whereas typical depression
is sometimes associated with loss of appetite.
Another striking difference is that SAD is
associated with hypersomnia, while people
with more typical depression often suffer from
insomnia. People with SAD tend to sleep from
10 to 14 hours a day. "The weight gain and
sleep is similar to bears who store up food for
hibernation in the winter," says Brainard.
Until recently, bright white fluorescent
light has been the gold standard for treating
SAD. A 1981 study showed that symptoms
significantly diminished in seven to 10 days
when patients sat by a 2-by-4-foot panel of
bright fluorescent light for up to four hours
each day. The current standard of treat-
ment is bright white light therapy for 30
to 60 minutes first thing in the morning
upon awakening. In the last decade, however,
Brainard and colleagues have discovered that
specific wavelengths of light corresponding
to different colors appear to be more potent
than others at alleviating SAD symptoms.
The difference lies not in how we perceive
the colors, but on an unconscious level.
Light travels from the retina into the brain
through two pathways. The more commonly
known pathway leads to the occipital lobe,
affecting our vision. The other pathway stim-
ulates biological and behavioral responses,
in part by triggering the pineal gland, which
secretes melatonin, the hormone that affects
sleep and has a role in controlling circa-
dian rhythms. A study by Brainard and his
colleagues showed the wavelength that has
the greatest influence on the pineal gland
is 464 nanometers, which corresponds to
blue not coincidentally the color of the sky.
Red, by contrast, is least effective.
On the Right Wavelength
In a Phase I clinical trial, just 45 minutes a
day in front of a blue light panel was shown
to significantly reduce symptoms of SAD,
compared with a placebo red light control.
Blue light also elicited a 50 to 60 percent
remission rate, similar to bright white fluo-
rescent light, but at a much lower dosage in
terms of brightness and time. "By getting
the wavelength right, you can use a gentler
light, which is an important finding for SAD
treatment, since it doesn't cause headaches
or eye strain like a stronger white light can,"
says Brainard.
Light therapy devices are commercially
available in several forms, including light
panels, workstations, dawn simulators and
head visors. Most light therapy products
use white light, but companies like Philips
are emerging as leaders in the light therapy
marketplace and now offer products with
blue light-emitting diodes (LEDs).
At Jefferson, light therapy research is moving
beyond SAD treatment. Brainard is working
with NASA to create a dynamic lighting
system for the International Space Station,
with the goal of reducing chronic sleep depri-
vation among astronauts.
"Astronauts are some of the healthiest people
in the world, but even the toughest person
can collapse from chronic sleep depriva-
tion," said Brainard. Back on Earth, such
research could have significant implications
for the 20 percent of the U.S. population
that works in jobs that require alertness
long after the sun goes down. What began
as a treatment for seasonal depression, light
therapy is helping even the healthiest among
us sleep (and wake) better.
George Brainard, PhD
14 JEFFERSON MEDICAL COLLEGE ALUMNI BULLETIN
WINTER 2012 15