What Does SAD Feel Like?
Brenda is a 37 year old woman who came to her
internist in November complaining of extreme fatigue. She had difficulty
waking up in the morning and found it increasingly more of an effort to
get anything done. She had no energy, little interest in her friends and
was irritable. She had gained 6 pounds and seemed drawn to sweets. Her
work was not getting done, the house was not picked up and she felt more
hopeless and depressed each day. Her history reflected similar problems
each winter and she looked forward to spring when she became "her usual
high energy self."
What Causes the Symptoms and Who Gets Them?
Brenda was suffering from Seasonal Affective Disorder
(SAD), often referred to as winter depression. The disorder is brought
on by the lack of bright light during the shortened days of winter.
Sometimes called the hibernation response, the incidence of SAD
increases with increasing latitude and is most prevalent in northern
regions with their prolonged winter nights. An estimated 6% of the
population suffers from full blown SAD. Another 14% experience a
sub-clinical level of SAD resulting in the common winter doldrums. Women
outnumber men 3 to 1 in reporting the disorder. Hormonal connections are
being explored as the incidence of SAD increases after puberty and is
reported less frequently by older women. It has also been associated
with worsened PMS symptoms.
The patient's tendency to overeat, oversleep, crave
carbohydrates and experience weight gain are characteristic of SAD.
These symptoms are considered atypical in contrast to the reduced sleep,
poor appetite and weight loss associated with classic melancholic
depression. Diagnosis is made on these "atypical" symptoms and the
patient's history of reoccurring winter blues, remitting in the spring.
Although researchers disagree on the exact cause, many
theorize that there exists a lack of enough morning light to suppress
the hormone melatonin. Studies show that blood levels of melatonin are
immediately suppressed by exposure to bright light boxes.
What Kind of Treatment is Available?
Light therapy is the preferred choice of treatment
because it is non-invasive and has a high success rate. Researchers
recommend an ophthalmological and medication history to screen patients
who have retinal problems or are taking photosensitizing agents. Those
patients should receive an ophthalmological exam and be monitored
closely or excluded from light therapy. Leading medical centers
successfully treat sleep and mood disorders with light therapy including
our own Oregon Health Science University.
How are patients treated?
response is achieved by replacing the light normally found in a long
summer day with artificial light. The patient is placed in front of a
light box that emits intense bright light. The
light enters the eye, hits the retina and is transmitted by nerve
impulses to the pineal gland which controls melatonin secretion. Intense
bright light is the key; full spectrum light is not required or
- The brightness of light is measured in Lux.
Therapeutic light boxes emit 2,500 to 10,000 Lux, 10 to 40 times
brighter than ordinary room light.
- Treatment duration varies but ranges from 15
minutes to 2 hours daily. The higher intensity light boxes require
- The timing of treatment may also be critical.
Although some researchers argue that any time is effective, most
research has indicated that morning light is far more effective.
- Exposure Method:
- Patients are cautioned not to stare at the light,
but to engage in reading or other productive activities while
sitting at a prescribed distance from the light. Many read, watch
television, do paperwork or eat breakfast.
- Relief begins in 3 to 4 days and is usually
complete within 2 weeks. Response if frequently dramatic and
patients who have suffered for years are profoundly relieved.
Remission of symptoms continues as long as the light sessions are
continued. Sessions can be discontinued when spring arrives with its
longer day duration.
should be designed to meet researchers specifications and be calibrated
so the patient knows at what distance to sit in order to receive the
proper Lux level.
Some insurance companies reimburse for the purchase of
light boxes. The Diagnostic and Statistical Manual of the American
Psychiatric Association lists the disorder as DSMIV-296.3X with
"seasonal pattern," and this coding should be used in applying for
What are the Other Applications of Light Therapy?
Light deprivation -- the primary cause of SAD -- is
usually the result of the shorter days and longer nights of winter. But
light deprivation may also be due to insufficient light exposure from
indoor working conditions, health and age-related indoor confinement,
shift work schedules, or unseasonably cloudy weather.
Light therapy is an exciting, fast growing field. It
is used to treat phase-advanced/phase-delayed sleep disorders, PMS, and
age-related insomnia. In can be instrumental in helping people overcome
jet lag and shift work schedule adjustments.