Phototherapy (Light Therapy)

Last edited on April 30, 2020

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Phototherapy (light therapy) is exposure to daylight or to specific wavelengths of light as a treatment. The light is administered for a prescribed amount of time and, in some cases, at a specific time of day.

Phototherapy is indicated for treatment of depression with seasonal affective subtype. It requires exposure to intense light under specified conditions (i.e. - sitting in front of light with eyes open, not staring directly at the light, and used in the mornings).

There is proven efficacy for midday light therapy for the treatment of bipolar depression.^[1]

The standard intensity of light needed is usually 5000-10,000 lux, ranging from 30-60 minutes per day. Overuse beyond the recommend amount does not confer any additional benefits.

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.^[2]

Bupropion has been shown to be effective in the prevention of SAD by starting treatment prior to the winter season.^[3]

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. As light is a stimulant, some users can develop nausea, irritation, and headaches (similar to taking psychotropic stimulants).

non-pharm

¹⁾ Sit, D. K., McGowan, J., Wiltrout, C., Diler, R. S., Dills, J., Luther, J., ... & Terman, M. (2017). Adjunctive bright light therapy for bipolar depression: a randomized double-blind placebo-controlled trial. American Journal of Psychiatry, appi-ajp.

²⁾ Parry, B. L., & Maurer, E. L. (2003). Light treatment of mood disorders. Dialogues in clinical neuroscience, 5(4), 353.

³⁾ Modell, J. G., Rosenthal, N. E., Harriett, A. E., Krishen, A., Asgharian, A., Foster, V. J., ... & Wightman, D. S. (2005). Seasonal affective disorder and its prevention by anticipatory treatment with bupropion XL. Biological psychiatry, 58(8), 658-667.