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Some
people with depression notice a seasonal pattern to their mood. They become depressed as the sunlight
fades in early or late Fall and gradually feel better as Winter turns to
Spring. During the depression, they
often eat more, especially carbohydrates, and feel tired despite sleeping
longer. Sometimes their mood swings
in Springtime towards exuberant energy and happiness, or even irritability.
This
pattern of depression is called Seasonal Affective Disorder (SAD). Part of the cause is thought to be a
problem with the circadian rhythm, which is a clock inside us that sets
levels of energy, sleep and appetite.
This biological clock is run by hormones and transmitters in our
brain, such as melatonin. Our brains
use sunlight to set this clock, and likewise people with Seasonal Affective
Disorder can use artificial sunlight through a lightbox
to correct their circadian rhythm.
Recently,
light therapy has been shown to help antidepressants work better, even when
used in the summertime and by people with non-seasonal depression [1].
Purchasing a Lightbox
Look for
the following features in purchasing a lightbox:
Intensity: at least 2,000 lux;
10,000 lux is optimal
Screen
Size: at least 12 x 17 inches
Wavelength: around 509 nM
(White Light)
Many
companies advertise portable boxes, even ones that fit on a visor, but these
are usually too small to be useful. This problem abounds when medical
products, such as lightboxes, are not regulated
by the FDA. Fortunately, a groups of researchers
in light therapy have stepped in to guide the public. Their group, the Center for Environmental
Therapeutics (CET), has a useful web site at:
http://www.cet.org/
The CET
has also approved the content at this commercial site, which links to
several distributors of light boxes (click on “Where to buy”):
http://www.day-lights.com/
A good
choice is the “DayLight XL”, which
has the right specifications for a low price ($170-200) and was used in
research studies. You can also
compare products by clicking on “Light for Life” then
“Which products should I choose?” (note: the DayLight XL is also sold at www.cet.org
under “products”).
Using Your Light Box
Although some products encourage
continual use throughout the day, research shows that between 30 minutes
and 2 hours of light exposure upon awakening brings the best effect. Bright light in the evening may cancel
out the effects of morning light. Try
to keep a regular sleep schedule and avoid staying up beyond 11pm (see www.aikenmd.com/sleep.htm
for advice on keeping better sleep).
Bring the directions for your lightbox to your doctor to find out how it should be
used for your condition. It is
important to sit at the right distance and angle (usually 45 degrees) from
the light to get the best dose. To
find out the optimal time to turn on the light, go to http://www.cet.org/
and click on “Online Self Assessment” and then AutoMEQ (in case the structure of this
site changes, the scale you need is called the “Automated Morningness-Eveningness Questionnaire” or autoMEQ).
It takes about 2 weeks for the
full effects of the light to set in, but many people begin to feel better
as early as 2-4 days after starting the light.
Side Effects and Precautions
Lightboxes are generally safe. It is important not to stare
directly into them as this can strain and even damage your eyes. Let your doctor know if you have any eye
diseases. The most common side
effect of the lightbox is headache. People with bipolar depression may
develop manic symptoms with the lightbox
(irritability, extreme happiness, high energy, talkativeness, racing
thoughts, insomnia); call your doctor if these occur.
More About Seasonal Affective Disorder
Seasonal
Affective Disorder typically comes on between ages 15 and 30. About 5% of people in the U.S. have
S.A.D., and up to 20% have milder forms of the condition.
Updated 10/22/6 by
Chris Aiken, M.D.
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Books on Seasonal Affective Disorder
Winter
Blues by Norman E. Rosenthal, M.D., 2005
Scientific References
[1] Martiny K, Lunde M, Unden M, Dam H, Bech P.
Adjunctive
bright light in non-seasonal major
depression:
results from clinician-rated depression
scales. Acta Psychiatr
Scand. 2005
Aug;112(2):117-25.
[2]
Golden RN, Gaynes BN, Ekstrom
RD, Hamer RM,
Jacobsen
FM, Suppes T, Wisner KL, Nemeroff
CB.
The
efficacy of light therapy in the treatment of
mood
disorders: a review and meta-analysis of the
evidence. Am J Psychiatry. 2005 Apr;162(4):656-62.
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