What is Light Therapy? A HealthCentral Explainer

  • seasonal affective disorder light box

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    Shorter days are already upon us, which means less daylight and less time spent outdoors.  For those who suffer from seasonal affective disorder (SAD), a type of depression that occurs typically in the fall and winter months, the shorter days are especially rough.  Bright light therapy is best known as a method used to treat SAD, but is also highly effective in treating other conditions, and new research is expanding the potential for this simple healing method.


    What is light therapy?

    During light therapy, also known as phototherapy or heliotherapy, a patient sits near a light therapy box that gives off a bright artificial light meant to mimic natural outdoor light.   Don’t worry, the amount of interior light being taken in by the eye is far less than what occurs outside, so relying on electric light doesn’t compare to the real thing.  Outdoor light on a sunny day is 500 to 1,000 times brighter than office or room lighting.   

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    The aforementioned light box is a very simple lamp that can fit on an office desk or anywhere in the home.  The amount of specific light rays and length of time the light box should be used is dependent on the condition being treated as well as the individual.  Treatment sessions range from 15 minutes to 3 hours, once or twice a day depending on the individual’s needs, and a person’s mood should start to improve within a week or so.  


    How is light therapy used to improve mental health?

    Light therapy was originally developed in the 1980’s by the National Institute of Mental Health to treat SAD, and it has been a very popular treatment method.  It is believed to affect brain chemicals linked to mood, resulting in a decrease in SAD symptoms.  It’s significantly cheaper than psychotherapy and medications, and it’s highly effective in treating seasonal depression with few side effects.   Minor side effects include headaches, eyestrain, or very rarely, an overactive state or feeling “too high.” 


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    Additionally, it can be used to treat depressive episodes with bipolar patients, a part of the disorder that currently has very few treatment options.  However, this requires careful monitoring, as too much light exposure can lead to manic episodes, and its effectiveness depends on light exposure at specific times of day. 


    For instance, a small study published in the journal Bipolar Disorder, examined nine bipolar women with depression who were instructed to use a light box in addition to their regular treatment, for two weeks for 15, 30, and 45 minutes a day.  Four women received morning light, and five received midday light.  Results showed that six women partially recovered with the light therapy, while three women achieved full recovery from depressive symptoms.  Midday light exposure for 45 or 60 minutes per day provided the best results.  Researchers found these results noteworthy since people with bipolar disorder can be very sensitive to morning light. 


    What about recent light box news?

    Last month another study on light therapy revealed that it could even lift the moods and cognitive performance of physically and mentally healthy people. The study was conducted by wearing a headset that would shine bright, full-spectrum light in the ear canal, directly to the photosensitive brain tissue of healthy participants.  Several series of the test were conducted, first on National Hockey League players, and next on a group of 41 students.  Participants received light therapy daily for 12 minutes a day over the course of three weeks. Their cognitive performance was evaluated by their reaction time to visual stimulus games.  The student subjects improved their reaction time by 25 to 50 percent compared to their prior performance and the control group.  The earlier study showed the hockey players also improved their reaction times by 25 to 30 percent compared to prior performances.  The study’s findings suggest that light therapy can have a significant effect on the moods and cognitive abilities of high-functioning people, suggesting that it could help actually prevent mental illness.  

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    Can bright light therapy be used for sleeping disorders?

    Light therapy is also a known treatment for circadian rhythm sleep disorders, where the pattern of sleep-wake is out of sync with the patient’s external environment. That can lead to fatigue and deterioration in cognitive performance.  Appropriately timed bright light therapy can help reset the timing of wake and sleep.  By improving sleep disturbances, the symptoms of depression, anxiety and PTSD should diminish since they are all closely linked. 


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    Can light therapy be used for psoriasis?

    Light therapy or phototherapy, as it is typically referred to for the treatment of psoriasis, uses several types of light to reduce skin plaques by exposing them to ultraviolet light on a regular basis.  Phototherapy to treat psoriasis requires medical supervision and is typically performed at the doctor’s office, although home units are sometimes used.  There are many different methods of phototherapy including laser treatments, tanning beds, and combinations of light rays.  A dermatologist should prescribe the best method for you, which may combine photo therapy with topical treatments and systemic medications. 


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    Does light therapy cause tanning?

    Light therapy shouldn’t cause any tanning since most light boxes shield out the ultraviolet light that causes tanning.  On rare occasions a patient with sensitive skin will experience some redness, which can be eliminated with filters and alternating bulbs.   




    n.p. (2012, August 30). "Bright Light Therapy Improves Cognitive Performance And Mood For Healthy People." Medical News Today. Retrieved from


    John’s Hopkin’s Health Alerts; Retrieved from http://www.johnshopkinshealthalerts.com/alerts/depression_anxiety/light-therapy-SAD_6028-1.html


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    Mayo Clinic; retrieved from http://www.mayoclinic.com/health/light-therapy/MY00195


    PsychCentral, “Bright Light Therapy,” retrieved from http://psychcentral.com/news/2008/01/04/bright-light-therapy-for-bipolar/1740.html

Published On: September 10, 2012