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Light Therapy for Depression

Light Therapy for Depression by Charles L. Watson

Do you feel sluggish, moody, or depressed during certain periods of the year?  It may not just be that you are sad but that you have SAD. Seasonal Affective Disorder affects your mood and triggers depression symptoms, often, during winter or fall when there’s not as much sunlight.  This disorder also is known as winter depression. Some people may experience it in summer, although this is rare.

You may be having SAD if for at least two years you have:

  • Had depression that begins and ends during a certain season.
  • Not experienced these symptoms during other “normal” seasons.
  • Had more seasons with depression than without over the years.  

There are medicines and other remedies for SAD, but one drug-free treatment is light therapy.

How Does Light Therapy Work?  

Light therapy is also referred to as phototherapy.  During light therapy, a person normally sits in front of a special fluorescent lamp or a box (a backlit light panel, one-foot-by-two-feet or larger) that gives off a maximum light of 10,000 lux, or 20 times brighter than most indoor lighting.  

Researchers believe that more serotonin—a neurotransmitter believed responsible for your feelings of happiness is produced by your brain with the help of the bright light.  

Daniel Kripke, a professor of psychiatry emeritus at the University of California, San Diego, told the Psychiatric Times in 1999 that the time had come to “accept bright light treatment” or phototherapy for treatment of depression.  Kripke had studied the connection between depression and biological rhythms from the early 1970s.  

In 1981, Kripke and his colleagues conducted clinical bright light studies that revealed that bright light produced an antidepressant effect in patients diagnosed with major nonseasonal depressive disorders.  One hour of light therapy reduced depression ratings by 12%—a statistically significant rate—in the first seven patients when compared to a placebo.  

Subsequent research by others found that light therapy successfully reduced nonseasonal depression scores by 12-to-35%, beginning in just one week or less, with additional benefits noted over the following weeks.  Pilot studies carried out on bright light being used a treatment for SAD showed improvement as well.

What’s less understood is why it works.  Kripke speculated that since many mammals experienced changes—lethargy, decreased sexual interest, and changes in appetites during winter, and increased activity, aggressiveness, and sexuality during summer—mainly due to the amount of sunlight, “depression might be analogous to winter responses and that light might be an effective treatment.”

Kripke also noted that since some depressed patients experience timing abnormalities associated with their circadian rhythms—the body’s internal clock that regulates our sleep-wake cycle, among other things—it might be because “light can correct timing abnormalities”.  

Whatever the reason, disruptions to your circadian rhythms can affect your quality of life and overall health.

Reasons for Trying Light Therapy

There are a number of reasons why you may want to try this type of therapy:

  • Your doctor has recommended it for your SAD.
  • You want to boost the effectiveness of psychotherapy and antidepressant medication.
  • You want to reduce your antidepressant medication dosage.
  • You want to try a treatment method that’s safe and has fewer side effects
  • You want to avoid having to use antidepressant medications, especially while pregnant or breastfeeding.

How to Prepare

First, consult your doctor, especially if you have any eye conditions—cataracts, glaucoma—or if you take medications for your SAD.  While a prescription isn’t required to purchase or use a light therapy box, there are potential negative side effects. Too much serotonin can be toxic.  Your doctor will be in a better position to recommend whether you should go ahead with light therapy or if you should take any precautions.  

Next, familiarize yourself with the different available light therapy box options and features, and discuss with your doctor the best type of light box for you.  This will help you buy a high-quality box that’s effective and safe.

When to Begin Light Therapy

Mostly, people with SAD begin light therapy treatment in early fall when it is cloudy in many parts of the country.  The treatment continues until spring when there is sufficient outdoor light to sustain higher energy levels and good moods.  

The symptoms of winter or fall depression may recur during other seasons when the light dims due to clouds or rain.  You and your doctor then can adjust the light treatment based on the duration and timing of your symptoms.


The effectiveness of light therapy depends on three main elements which are:

  • Timing.  For many people, the therapy works best in the morning, but your doctor will recommend the best time for you.
  • Intensity.  For SAD treatment, you should be exposed to at least 10,000 lux of light at a distance of two feet or less from the light box.  
  • Duration.  A therapy session should ideally last anywhere from 20 to 30 minutes.  That’s with a recommended 10,000-lux box. If, on the other hand, your light box has a lower-intensity of say, 2,500 lux, you may need longer sessions.  

What to Do During Light Therapy Treatment

For as long as 30 minutes a day, the individual with SAD sits about 16 to 24 inches away from the light, either working or sitting, because for light therapy to work, skin exposure is not enough; the light must enter into the pupils, but indirectly.  Your eyes should be open, but don’t stare directly at the light box or you might damage your eyes.

Remember to follow the manufacturer’s and doctor’s directions.  

Light therapy needs consistency and time.  Set the box strategically on a desk in your office or on the table at home.  That way, you’ll be able to work, watch TV, use your computer or phone, and eat while receiving light therapy.  Adhere to your schedule, but don’t overdo it.

Individuals should show significant improvements after about one to two weeks.  

Light Therapy Side Effects

Some of the mild side-effects associated with the therapy can include:

  • Nausea
  • Blurry vision
  • Headaches

The above symptoms should disappear within a short period of time.  


Charles L. Watson currently is the head content writer for Sunshine Behavioral Health.  When you don’t catch him at a local Detroit Pistons game, you will find he reading updated material from his favorite author Tim Ferriss.  He can be reached directly on Twitter at @charleswatson00.

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