Shedding Light on
Those Winter Blues
by Patricia McManus
Reprinted from MD Magazine - January 1984
Does your spirit wane with the shortening days? You may be suffering
from sunlight withdrawal.
The syndrome appears with inevitable regularity.
As summer pales into autumn, the victim feels an
ominous sense of anxiety and foreboding at the mere
thought of approaching winter. As days shorten from
November into December, there's a gradual slowing
down, a loss of energy, a need for more and more
sleep, a longing to lie undisturbed in bed.
It becomes harder to get to work, to accomplish
anything when there. Depression and withdrawal follow.
As a Brooklyn, New York, woman described it, "Everything
seems gloomier and more difficult. There is a sadness
looming over everything. I can't concentrate at
work and feel like going home afterward to hibernate
like a bear."
Just as routinely, as spring approaches and days
stretch out, the sufferer flips into high gear.
"Once the warm weather arrives, I feel a burden
lifted," says the Brooklynite. "I feel
freer and happier."
This is more than a dislike of icy slush and raw
winds. Psychiatric researchers at the National Institute
of Mental Health (NIMH) have identified these complaints
as a previously unrecognized clinical syndrome.
They call its victims "winter depressives."
"It is much more common than we thought,"
says Dr. Norman Rosenthal of NIMH. "We expected
to get a few replies from our description of this
pattern. Instead, we received more than three thousand
responses from all over the country. The symptoms
described were one after the other very much the
same."
Some of these winter depressives are being successfully
treated, not with drugs or psychotherapy but with
an element common to all our lives: artificial light.
What scientists are learning from the use of light
as it affects health and mood has implications for
us all. It forces us to rethink the way we light
up our lives, especially urban dwellers and workers
who spend so much time indoors. Apparently artificial
light does much more than enable us to read and
work without benefit of sunlight. It affects our
bodies.
"It is important to recognize that this is
a distinct syndrome with a well-defined cluster
of symptoms," says Dr. Thomas Wehr, an NIMH
researcher. "We have measured some very interesting
physiological changes specific to this kind of depression."
While typically depressed people have impaired
sleep patterns and usually wake up early, winter
depressives might sleep nine or 10 hours a night,
wake up tired, and take naps. There is a 50% reduction
in delta sleep, the deepest, most restful phase
of the sleep cycle. Winter depressives gain weight,
crave carbohydrates, and their libido pales. Their
energy levels drop; monitors on their wrists show
that they are less active than in summer.
Such symptoms begin earlier the farther north they
live and abate. When they visit sunny southern climates
in the winter. Symptoms peak and wane according
to the length of days. In New York, for instance,
on the shortest day of the year - December 21 -
the sun rose at 7:17 A.M. and set at 4:32 P.M.,
contrasted to 5:25 A.M. and 8:31 P.M. at the height
of summer, a six hour difference in light. Such
a distinct seasonal pattern implicates the external
environment as the culprit, the most obvious being
sunlight.
Sunlight has already been shown to trigger cycles
and seasonal behavior in animals, including reproduction,
hibernation, migration, and molting. Animal behavior
has been fooled by artificial light. Could it also
fool humans? Apparently.
In a recent NIMH study, a group of these depressives
were treated with amounts of light that simulated
that of summer days. Short winter days were stretched
by six extra hours of light. The subjects were awakened
before sunrise to bask in three hours of light,
and dusk was delayed for three more hours.
Since sunlight is thought to be the missing element,
the subjects were flooded with an artificial light
that most closely resembles the full broad spectrum
of the sun, a fluorescent tube called "Vita-Lite."
At 20 times the intensity of normal indoor lighting,
the light approximated the sensation of sitting
on a shady porch or under a tree in mid-summer.
Fluorescent lamps are roughly three times more intense
than ordinary light bulbs.
A bank of eight 40-watt fluorescent bulbs at eye
level lit the participants' rooms as they read,
worked, or moved around. Within days this group
responded with measurable mood changes, says Rosenthal.
Their symptoms eased and energy levels rose, while
a control group with a different threshold of light
showed no change in behavior.
"Something in the external environment caused
these changes," says Wehr, "but we are
not prepared to say exactly what it is at this point.
It is true, though, that waking up these people
and exposing them to this light treated their symptoms.
Whether it is the break in sleep pattern, the wavelengths
or intensity of light, or some other factor we can't
say at this point. We don't know if the Vita-Lite
is the essential element, although it may be."
The intensity of light used in the study may be
well in excess of what is necessary to effect changes,
stress the researchers. So they will continue to
experiment with varieties of light therapy to determine
the crucial element. The subjects themselves feel
that sunlight is the missing ingredient. One said
that she felt as if she were in a "lower state
of evolution since I function by photosynthesis."
Although these winter depressives showed an abnormal
response to light, each of us responds to it in
varying degrees. External light travels on a direct
pathway from the retina to the part of the hypothalamus
believed to be involved in running our biologic
clock, the suprachiasmatic nuclei. The path continues
to the tiny, cone-shaped pineal gland, which secretes
the hormone melatonin. It is thought that melatonin
affects the regulation of behavioral changes in
animals, but this has not been clearly shown in
humans. Sufficiently intense light suppresses the
secretion of this chemical, making it a useful marker
in determining light's physical effect on behavior.
The secretion of melatonin reflects light's effect
on the hypothalamus, itself highly sensitive to
light. This complex part of the brain regulates
a multitude of body functions, playing a vital role
in reproduction, thirst, hunger, satiation, temperature,
emotions, and sleep patterns. Depression is associated
with disturbances in the hypothalamus.
"By stimulating the hypothalamus with light
we may be correcting these disturbances in this
group," explains Rosenthal.
Most artificial light differs from natural sunlight
in wavelength (color) and intensity. Sunlight is
very intense electromagnetic energy in a continuous
spectrum of colors ranging from the short wavelengths
of invisible ultraviolet light (UV) through blue,
green, yellow, and into the infrared waves. The
majority of our homes are lit by incandescent bulbs
that light through heat. They lack the intensity
of sunlight and produce light that is heavily infrared.
"We don't like the incandescent lights,"
says Wehr. "It's conceivable for this purpose
that they are not the safest. You can get burned
from the heat and the infrared radiation.
Although some fluorescent lamps are described as
"broad spectrum," they do not have the
same distribution of colors as sunlight. Widely
used fluorescent lights peak in the yellow-green
portion of the spectrum, wavelengths to which the
eye is most sensitive. That makes them energy efficient
but different from natural sunlight, notably in
the blue-green spectrum where the sun's emission
or radiant energy is strongest. Additionally, conventional
indoor lighting lacks the proper proportion of near-UV
radiation of the sun that advocates claim to be
vital to health and well-being.
This is a pivotal point in the world of lighting.
The Vita-Lite bulb purports to be healthy for plants,
animals, and people because it is so close to natural
sunlight. Skeptics say that the need for an indoor
equivalent of sunlight has yet to be proved, especially
given that UV radiation has been linked to skin
cancer. Believers in Vita-Lite say that sunlight
is essential to living creatures and that the large
blocks of time we spend indoors deprive us of sufficient
amounts, including UV.
Just as overexposure can be unhealthy, regulated
doses of sun and UV can be therapeutic. UV is currently
used to treat psoriasis and, experimentally, genital
herpes and some forms of cancer in the early stages
of the illness. Full-spectrum artificial light is
widely used to cure a potentially fatal type of
infant jaundice. We need sunlight with its UV rays
to metabolize vitamin D, necessary for the absorption
of calcium, especially in growing children and the
elderly.
Some studies show that working under true full-spectrum
lights enhances productivity and reduces fatigue.
Even critics concede that many people who are deprived
of natural light, such as night or shift workers,
suffer undue emotional stress.
Whether or just how we should alter our indoor
lighting is a question being raised by these studies.
As Dr. Richard Wurtman, professor of endocrinology
and metabolism at the Massachusetts Institute of
Technology, has been saying for years, we should
not take artificial lighting for granted. Lined
up in the pro-sunlight camp, he has written, "Light
is potentially too useful an agency of human health
not to be more effectively examined and exploited."
As researchers isolate the specific part of the
sun's spectrum that is related to health and well-being,
we could eventually create the perfect indoor environment
with artificial lighting, says E. Woody Bickford,
environmental engineer with Duro-Test, manufacturers
of Vita-Lite. "Until we know," he points
out, "Vita Lite, with its complete range of
visible and invisible light, is what we have to
work with."
For ordinary indoor lighting, two to four 40-watt
lamps would provide some health benefits, he says.
"The benefits seem to be proportional to the
amount of light," he adds. "We may need
higher intensity in all our work levels. Perhaps
the cutoff point is what you can afford." Vita-Lite
tubes are expensive, and most of our homes are not
equipped with fixtures that can accommodate them.
Although many lighting experts are skeptical of
the entire concept of light affecting our health,
some light manufacturers are beginning to support
research in the field, and one trade association
has just established a new branch devoted to light
and health.
As the relationship between light and health becomes
publicized, NIMH's Rosenthal worries that people
will try to treat themselves. "With the winter
depressives it's a matter of risks outweighing benefits.
Bright light can damage the retina; UV can be dangerous.
But depression can be dangerous for them, too!"
Rather than attempting to cure themselves, people
who think that they are winter depressives should
contact the NIMH, Bethesda, Maryland 20205, for
literature and specific recommendations as they
become available. As Dr. Wehr puts it, "we
are not telling people to hurry and turn lights
on - not yet."
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