afety of phototherapy
Ultraviolet light causes progressive damage to human skin. This is mediated by genetic damage, collagen damage, as well as destruction of vitamin A and Vitamin C in the skin and free radical generation.
Visible blue light has been suggested to cause DNA breaks, but carcinogenesis has not been demonstrated, and enzymes within the cells are believed to repair the breaks reasonably well.[citation needed] However, cancer has been induced in cells with deliberately damaged repair mechanisms. Also, researchers have questioned whether limiting blue light exposure could reduce the risk of age-related macular degeneration (ARMD).
Modern phototherapy lamps used in the treatment of seasonal affective disorder do not emit ultraviolet light and are considered safe and effective for the intended purpose, as long as photosensitizing drugs are not being taken at the same time and in the absence of any existing eye conditions. Light therapy is a mood altering treatment, as just as with drug treatments, there is a possibility of triggering a manic state from a depressive state, causing anxiety, and other side effects. While these side-effects are usually controllable, it is recommended that patients undertake light-therapy under the supervision of an experienced clinician, rather than attempting to self-medicate.
Contraindications
There are few absolute contraindications to light therapy, although there are some circumstances in which caution is required. These include when the patient 1) has a condition that might render his or her eyes more vulnerable to phototoxicity, 2) has a tendency toward mania, 3) has a photosensitive skin condition, or 4) is taking a photosensitizing medication or herb. Patients with porphyria should avoid most forms of light therapy. Patients on certain drugs like methotrxate or chloroquine should use caution with light therapy as there is a chance that these drugs could cause porphyria.
Side effects
Side effects of light therapy for sleep phase disorders include jumpiness or jitteriness, feeling "wired," headache, and nausea. Some nondepressive physical complaints (such as poor vision and skin rash or irritation) may improve with light therapy (M. Terman and Terman 1999).