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What Are the Risks of Light Treatment?

Some individuals will experience eyestrain or headache and may benefit from increasing the distance to the light box temporarily. Ophthalmological studies have been done with patients using medical-grade 10,000 lux light boxes. Such work has shown no damage to the eye from the treatment. Nevertheless, we do not recommend bright light treatment for patients with retinal diseases such as macular degeneration, or diseases such as diabetes which could be associated with retinal disease. If you have any such illness, you should consult with an eye doctor before doing bright light treatment. We also recommend individuals over 65 consult with their eye doctor before proceeding with light treatment. No medical treatment is without risk. Being outside during a sunny day could expose the eye to more than 10,000 lux, so the risks of light treatment with a standard device seem likely to be small compared to the benefit of treatment. There are no long-term studies of the effects of light treatment done each year for many years, so definitive information is still lacking.

Other individuals may find themselves becoming overstimulated while starting treatment and may decide to decrease the duration of treatment to 15 minutes per day for a week or two. Rarely light treatment may lead to a bipolar hypomanic or manic state. This is a state of overactivation and could lead to inappropriate and dangerous behaviors. Light treatment must be monitored with particular caution in individuals with bipolar disorder. In some cases, these reactions can be treated by reducing the duration of treatment as noted. Therefore, we emphasize that light treatment must be done only under the supervision of a clinician qualified to treat mood disorders.

All forms of antidepressant treatment can produce an increase in energy and agitation. When such an effect precedes an improvement in mood, antidepressant treatment could bring on suicidal ideation or predispose to suicide. There are a small number of reports or such responses to light treatment. Again, light treatment must be done only under the supervision of a qualified clinician.

Some medications or illnesses can result in a rash or other reaction to bright light. In general, these reactions are to ultraviolet (UV) light while properly designed light boxes emit no UV. It seems cautious to avoid bright light treatment while you are using a photosensitizing medication. Photosensitizing medications include antibiotics such as fluoroquinolones (ciprofloxacin, levofloxacin, others), tetracyclines (doxycycline, others), sulfonamides, or antimalarials (quinine, chloroquine, and hydroxychloroquine, others) and nonsteroidal drugs (NSAIDs) such as naproxen or piroxicam, as well as certain antihistamine, antidiabetic, antidepressant, and antipsychotic medications. Check with your doctor if he/she advises against exposure to sunlight with any medication you are taking.

How Can I Tell if I'm Getting 10,000 Lux of Light?

There are free apps for your Android or iPhone that can measure the intensity of light in units of lux. These apps use the front-facing camera on the phone. You can make sure you are at a distance to receive 10,000 lux. You can also check how far off center you can still receive close to 10,000 lux.

Is Blue Light Better in Treating SAD?

Blue light probably has stronger effects on the circadian rhythm system, the “body’s clock.” However, blue light is also more toxic to the retina. At this time, we recommend broad spectrum white light as the best balance of risk and benefit. Another nonprofit entity, the Center for Environmental Therapeutics, also recommends broad spectrum white light: please see their website at In the future, we have speculated that green light may be safest option, but the proper research simply has not been done yet. We discuss this issue in our publication shown in the References below (Oldham et al, 2019).