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.

Do Not Stare Directly at the Light!

The proper way to use a light box is to sit in front of light with your eyes open, but to not staring directly at the light.
  • 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.