Light therapy has very rarely been associated with mild side effects, and these are not typically dangerous. In comparison to the potential adverse effects of antidepressant medications, the side effects of light therapy are generally minimal. What further favors light therapy is that any side effects, if they occur, are usually temporary and can often be resolved by reducing exposure time. Different individuals may have varying thresholds for light therapy, so it's important to find your own optimal level of exposure.
Some of the most common initial side effects of light therapy include headaches, eye discomfort (itching or stinging), and occasional mild nausea at the beginning of treatment. Typically, these effects diminish within a few hours after each session and may disappear entirely after several exposures. Unless the discomfort is severe, it's advisable to endure these minor irritations for the first few days (after consulting a specialist) until your body adjusts to the light. If the irritation persists or worsens after four days, consider sitting a bit further from the light source, reducing exposure time, and consulting a healthcare professional experienced in treating Seasonal Affective Disorder (SAD).
The most uncommon and dramatic side effect is a switch to an overactive state, during which one may experience difficulty sleeping at night. This state is particularly prevalent in people who have experienced similar states during late spring or summer. In such cases, it's crucial to receive guidance from a skilled clinician to optimize light therapy. If eye irritation lingers, sitting farther from the lights or using the lights for shorter periods can help, as can installing a humidifier.
Some individuals may report experiencing visual glare under bright light therapy, which can be mitigated by using a tilted light box design. A major source of visual glare is short-wavelength blue light, a component of the white light used in therapy. If this causes discomfort, specially designed eyeglass lenses can be used to filter out the blue light without significantly affecting the light's intensity reaching the retina.
It's worth noting that during a cold or viral infection, you may experience irritability while undergoing light therapy. However, the positive effects of the light treatment will generally return soon after the infection or virus has cleared up.
Light Therapy Is Not Recommended If You:
If you have an eye or skin condition that is exacerbated by bright light, it is advisable to consult a healthcare professional before starting light therapy. Individuals with conditions such as glaucoma, cataracts, retinal detachment, or retinopathy should avoid bright light therapy, as it could worsen their eye condition or exacerbate a skin condition. If you have hypertension, diabetes, or a family history of eye disease, seeking medical advice before starting light therapy is highly recommended.