Light Therapy for Depression

Light Therapy for Depression
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If you have a type of mood disorder called Seasonal Affective Disorder, also known as Major Depressive Disorder With a Seasonal Pattern, you may suffer from depression only during specific times of the year. Seasonal depression commonly occurs during the fall and winter, when the number of daylight hours decline, although it may fall into other seasonal patterns as well.

Researchers believe that a lack of light exposure, especially in the early morning, may cause this type of depression by throwing off a person's circadian rhythm, which is regulated by environmental light entering the eye.

The best type of treatment for seasonal depression is considered to be light therapy using a light emitting-device called a light box. Light therapy is aimed at increasing a person's exposure to light in order to reset their circadian rhythm. 

Ideally, it is best to seek the guidance of a mental health professional if you suffer from winter depression, especially if it tends to be severe or accompanied by thoughts of suicide. In addition, health insurance generally covers the cost of a light box that has been recommended by your physician. However, a prescription is not required to purchase a light box; and, if your depression tends to only be mild to moderate you may wish to purchase a light box and self-treat your winter blues.

How to Use a Light Box

The best light box, according to the Center for Environmental Therapeutics is one that:

  • Provides 10,000 lux of illumination.
  • Has gone through clinical testing to confirm its effectiveness.
  • Has UV filters to filter out harmful rays.
  • Has white light.  (Although there are units which provide blue light only, there is no proven advantage with these light boxes and there is a theorized risk that they may contribute to macular degeneration.  Given that white light has a very good safety record, it is wise to stick with it until more is known about the safety of blue light.)
  • Minimizes glare by projecting the light downward at an angle.
  • Is a large enough size that small head movements do not take the eyes out of the therapeutic range.

Using a light box involves sitting in front of it for a specified period of time (30 to 90 is typical) with your eyes facing it, but not looking directly at it. Research indicates that early morning is probably the best time for light therapy. A light box is designed to provide the needed lux level when your eyes are at a particular distance from it, so you will want to be sure that you are at the proper distance to receive the best therapeutic effect. You will be able to do other activities such as reading or working on your computer during this time if you desire because the light enters your eyes regardless of where you are looking as long as you are facing the light box. The best time to start light therapy is at the beginning of the season when your symptoms first typically begin to affect you. You may need to start with a lower dose early in the season, increasing your daily exposure to light as the season progresses and days become shorter.

If light therapy works for you, you may feel lighter in mood, calmer and more energetic. The strong appetite and carbohydrate cravings that are often associated with winter depression may become less.  Thinking and decision-making may become easier. Exercise and other physical activity may become more appealing as well.

Although the effects vary from person-to-person, people will generally start to feel better within about two to four days after beginning treatment, although it could take longer.

Possible Side Effects

Some people may experience side effects from light therapy, especially if their dose is too high.  Reducing the time that you sit in front of the light box should take care of these problems. Side effects may include:

  • Headaches
  • Eyestrain
  • Irritability
  • Anxiety
  • Overactivity
  • Sleeplessness
  • Upset stomach
  • Tiredness
  • Dry eyes
  • Dry nasal passages and sinuses
  • Sunburn-type reaction of the skin

Sources

CET.org.  Center for Environmental Therapeautics.  Accessed:  November 23, 2015.

Rosenthal, Norman E.  Winter Blues:  Everything You Need to Beat Seasonal Affective Disorder.  Fourth Edition.  New York: Guilford Press, 2013.

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