Some patients undergoing light therapy treatments report side effects of eyestrain, headaches, insomnia, fatigue, sunburn, and dry eyes and nose. Most of these effects can be managed by adjusting the timing and duration of the light therapy sessions. A strong sun block and eye and nose drops can alleviate the others. Long-term studies have shown no negative effects to eye function of individuals undergoing light therapy treatment.
A small percentage of light therapy patients may experience hypomania, a feeling of exaggerated, hyperelevated mood. Again, adjusting the length and frequency of treatment sessions can usually manage this side effect.
Research & general acceptance
Light therapy is widely accepted by both traditional and complementary medicine as an effective treatment for SAD. The exact mechanisms by which the treatment works are not known, but the bright light employed in light therapy may act to readjust the body's circadian rhythms, or internal clock. Other popular theories are that light triggers the production of serotonin, a neurotransmitter believed to be related to depressive disorders, or that it influences the body's production of melatonin, a hormone that may be related to circadian rhythms. A recent British study suggests that dawn simulation, a form of light therapy in which the patient is exposed to white light of gradually increasing brightness (peaking at 250 lux after 90 min) may be even more effective in treating depression than exposure to bright light. Dawn simulation is started around 4:30 or 5 o'clock in the morning, while the patient is still asleep.
Wide-spectrum UV light treatment for skin disorders such as psoriasis is also considered a standard treatment option in clinical practice. However, such other light-related treatments as coldlaser therapy and colored light therapy are not generally accepted, since few or no scientific studies exist on the techniques.
Paula Ford-Martin, Rebecca J. Frey PhD, The Gale Group Inc., Gale, Detroit,