SAD is a recurring prolonged period of depression, whose onset and remission coincides with
changes in the seasons. In most cases the depression begins in late fall or early winter and
persists until spring or sometimes even into summer. Slightly more women than men report suffering
from SAD, and the majority of those afflicted with SAD are under the age of 40.
According to Dr. Kathleen B. Speicher of the Student Health Center, Indiana University—Purdue
University Indianapolis, the common symptoms of SAD include "a change in appetite (especially a
craving for sweet or starchy foods), weight gain, a heavy feeling in the arms and legs, a drop in
energy level, fatigue, a tendency to oversleep, difficulty concentrating, irritability, increased
sensitivity to social rejection and avoidance of social situations (hibernation)."
Some scientists believe that it is not so much the reduced number of daylight hours which
promotes the onset of SAD, but rather the winter sunlight itself being less intense, often further
diffused by heavy cloud cover. Others theorize that waking up on winter mornings prior to sunrise
upsets the body’s internal "clock," which is believed to be "synchronized" to local time through
exposure to morning daylight. Still other researchers suggest that SAD may actually be the result of
a combination of these effects, or even other effects that have not yet been identified.
Light Therapy for SAD Sufferers
About 20 years ago, it was first demonstrated that exposing humans to high-intensity light could
actually bring about positive changes in the brain chemistry and help to counteract feelings of
depression. So it was theorized that exposing people to increased amounts of intense light in the
wintertime might have a similar beneficial effect upon those suffering from winter depression. And
subsequent research has conclusively proved that light therapy does indeed significantly help many
who suffer from SAD.
One study, reported in the Archives of General Psychiatry (October, 1998), was conducted
by Dr. Charmane Eastman of Rush-Presbyterian St. Luke’s Medical Center in Chicago. According to a
report of her study on ABC News, "61 percent of people who got morning light therapy and 50 percent
of people who got evening light therapy experienced nearly complete recovery from their seasonal
depression after four weeks of treatment."
Another prominent researcher, Dr. Raymond W. Lam, described the current recommended procedure for
administering light therapy in the October 2002 issue of Psychiatric Times. "The recommended
protocol for light treatment," he explained, "is 10,000 lux exposure, administered by a fluorescent
light box with an ultraviolet filter, for at least 30 minutes per day in the early morning (Lam and
Levitt, 1999). Less intense light usually requires greater duration of exposure for the same
response, e.g., 3,000 lux for one to two hours." Dr. Lam commented that improvement is often noted
after only one week, with most patients noticing improvement within 2 to 4 weeks. Patients generally
suffer relapse after the treatments are stopped, so they must be continued until the time of year
when the symptoms of SAD would otherwise have subsided without light therapy.
Commenting on several recent clinical studies of light therapy for SAD, Dr. Anna Wirz-Justice, of
the Psychiatric University Clinic in Basel, Switzerland, wrote in an editorial in the October, 1998
issue of the Archives of General Psychiatry, "Light is as effective as drugs, perhaps more
so." She went on to comment, "Light is an effective antidepressant in seasonal affective disorder
(SAD)… Light therapy is easy to administer in out patient settings, lacks major side effects, and,
importantly, is cost effective."