Light Therapy for Depression

By Maggie Hahn, APN/CNS, ext. 362


For about the last 20 years, using light to treat depression has been an accepted technique. But what does light actually do?


Light has been shown to be a powerful synchronizer of our internal circadian clocks. The master clock is located in the hypothalamus of the brain, which receives light signals in a direct pathway from the eye. This structure controls melatonin secretion. Melatonin is sometimes referred to as the sleep hormone. In turn, melatonin synchronizes our core body temperature, cortisol levels, blood pressure and many other body functions.  When these are all in sync, we sleep well and our moods are stable.


Many people feel worse in the darker winter months, and symptoms of depression can worsen dramatically. Sleeping more, eating more, craving carbohydrates, and feeling extremely depressed are symptoms of SAD or seasonal affective disorder.  Using a light box every morning can make your body behave as if it is experiencing bright spring mornings, instead of dark winter mornings.


Light can be used alone or in combination with antidepressant medications or mood stabilizers. It has a rapid onset of relief, sometimes in 5-7 days.  It is physically safe for most people, but is not appropriate for those with macular degeneration of the eyes.


Light boxes should have 10,000 lux bright white light, and be positioned slightly above your face, shining down on you, at a distance of about 12-15 inches.  You can eat  breakfast , read, answer email, etc. Most people can tolerate 20-30 minutes every morning. Those with Bipolar Disorder should start with a very short exposure and slowly increase because light is powerful enough to precipitate mania in Bipolar Disorder.


Although light boxes can be bought without a prescription, an evaluation by a mental health professional well versed in light therapy is best. They can diagnose your depression, prescribe the optimal timing for your light therapy and often help you get insurance reimbursement for the light box.


An excellent resource for information on light therapy is the website of The Center for Environmental Therapeutics (cet.org).