Light therapy is treatment
with a special type of light that is much brighter than a lamp or other light
fixture in your home. The most common form of this therapy is done with a light
box that contains fluorescent—not ultraviolet or full-spectrum— lights.
To use light therapy, you sit at a prescribed distance from the light
box. The amount of exposure you need depends on the intensity of light you use
and could range anywhere from 30 minutes to 2 hours. The intensity of light
usually ranges between 2,500 and 10,000 lux (10,000 lux is about 20 times as
bright as normal indoor lighting).
Although light boxes are the
most common type of light therapy, dawn simulation is also used. With dawn
simulation, a low-intensity light gradually comes on while you're sleeping,
about 2 hours before you usually wake up.
The amount of time you need to sit in front of a light
box depends on how strong of a light you use.
The amount of exposure you need depends on the
intensity of light you use and could range anywhere from 30 minutes to 2
Continue to Why?
who have seasonal affective disorder become depressed in the fall and winter, when
days are shorter and sunlight is limited. Although researchers are still
studying the exact cause of SAD, some believe the body's 24-hour biological
clock (circadian rhythms), which controls sleep-wake cycles,
may be affected by seasonal changes of light and darkness and that subsequent
biochemical changes in the brain may cause depression. Light therapy helps to
"reset" your biological clock.
Light therapy, which has few side
effects, is also an alternative to taking medicines to treat depression. It can
also be used with medicines and counseling.
Professional counseling, medicine, or a combination of
the two may still be needed even if you have light therapy.
Light therapy alone may be enough to make you
feel better, but many people with depression also need professional counseling
Continue to How?
Most light therapy is
prescribed at 10,000 lux for about 30 minutes to 2 hours in the early morning.
Studies vary as to whether light therapy at other times of the day is less
effective. But some people with SAD (perhaps those who wake up normally in the
early morning) should do their light therapy for 1 to 2 hours in the evening,
ending 1 hour before bedtime.
Some people who find it
inconvenient to use a light box may want to try dawn simulation.
When you begin light therapy, your first response will show you
whether you need to adjust the intensity or duration. Many people respond to
light therapy within 3 to 5 days. If you don't respond to treatment within the first week, you
may notice improvement in the second week.
The most common side
effects of light therapy include headache, eye strain, and nausea. You may be
tired during the first week because of changes in your sleep-wake patterns, but
this will usually go away after about a week.
Light therapy is
usually started in the fall and continued through spring.
doctor can help you decide which light exposure schedule will work best for
you. Most lights used in light therapy can be found on the Internet. Beware of
manufacturers that market inexpensive light therapy devices that have not been
researched for effectiveness or documented for safety. The safest light is
fluorescent, not full-spectrum or ultraviolet light.
If you have
any eye problems, talk with your
ophthalmologist before beginning light therapy. Also,
make sure your doctor knows all of the medicines you are taking.
I should receive 10,000 lux of light therapy each
morning for about 30 minutes to 2 hours every day.
Your doctor will help you determine the most
effective amount of time you need to be exposed to light therapy daily. You may
want to start with 30 minutes to 2 hours of light therapy daily and adjust the
time based on your first reaction and reduction of symptoms. You should not
use a lamp that puts out more than 10,000 lux of light at a distance of 12 to
Continue to Where?
Talk with your doctor
Take this information with you and work with your
doctor to create a treatment plan that works for you.
Return to topic:
Seasonal Affective Disorder
Other Works Consulted
American Psychiatric Association (2010). Practice Guideline for the Treatment of Patients With Major Depressive Disorder, 3rd ed. Available online: http://psychiatryonline.org/guidelines.aspx.
June 20, 2012
Kathleen Romito, MD - Family Medicine
& Alfred Lewy, MD, PhD - Psychiatry
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