Phototherapy (Light Therapy)

Phototherapy (Light Therapy) is exposure to daylight or to specific wavelengths of light as a treatment for psychiatric disorders. The light is typically administered at home with a fluorescent light box for a prescribed amount of time and, in some cases, at a specific time of day.

• Light therapy is indicated as a first-line treatment of depression with seasonal affective subtype.
• For non-seasonal depression, it is a second-line monotherapy or adjunctive treatment for mild to moderate nonseasonal major depressive disorder.
• There is proven efficacy for midday light therapy for the treatment of bipolar depression.^[1]

• Light therapy's mechanism of antidepressant action is thought to be due to the modulation of serotonin and catecholamine systems, as well as alteration of circadian rhythms in the body.

• The standard intensity of light needed is usually 10,000 lux (light intensity) for 30 minutes per day in the early morning for a period of 6 weeks.^[2]
• Overuse beyond the recommend amount does not confer any additional benefits.

• Response to treatment is usually seen within 1 to 3 weeks
• The average consensus is treatment time of 6 weeks.^[3]

• Phototherapy is effective in 2 out of every 3 SAD patients treated. It works rapidly, but also loses efficacy rapidly upon discontinuation (and thus requires daily, consistent use). Individuals who have symptoms of high carbohydrate cravings and/or hypersomnia have the best response to phototherapy.^[4]

• Light therapy is generally very well tolerated.
• The most common side effects are eye strain, headache, irritation, agitation, nausea, and sedation.

• Risks of phototherapy include phototherapy-induced mania/hypomania in those predisposed, interactions with light sensitizing medications (digitoxin, ibuprofen, chlorpropamide), and a relative contraindication is there is existing retinal disease.