A new scientific era may have dawned for light therapy, a potential depression fighter that has languished in the shadows of antidepressant medication and psychotherapy for the past 20 years.
A research review commissioned by the American Psychiatric Association in Washington, D.C., concludes that in trials, daily exposure to bright light is about as effective as antidepressant drugs in quelling seasonal affective disorder (SAD), or winter depression, and other forms of depression.
“I now tell my patients that light therapy is a reasonable depression treatment, even if the data base for this approach is relatively small,” says psychiatrist Robert N. Golden of the University of North Carolina at Chapel Hill. Golden directed the new statistical review, which appears in the April American Journal of Psychiatry.
Like many mainstream psychiatrists, Golden had been skeptical of studies reporting that depression diminishes in response to daily bright-light exposure, usually administered early in the morning for 30 minutes to 1 hour. These investigations often contain serious flaws, he says, such as few participants and no groups treated with dim lights or other placebos.
The new review supported Golden’s skepticism about research quality. Of 173 published light-treatment studies that his team considered, only 20 passed muster on their design and controls. Those tests lasted between 1 week and 6 weeks and typically included about 20 participants. But to Golden’s surprise, pooled data from the acceptable investigations showed markedly eased SAD symptoms from both bright-light exposure after awakening and dawn simulation, in which a light box each morning provides a sleeping person with gradually intensifying illumination.
Moreover, light therapy yielded substantial relief for outpatients with mild-to-moderate depression unrelated to any season. Such therapy also magnified the depression-fighting effects of antidepressants in these individuals.
Questions remain about light therapy, Golden notes. It hasn’t been studied with patients hospitalized for severe depression.
Researchers also need to examine whether specific light doses can cause or aggravate eye problems such as cataracts, Golden adds. “That’s a concern, but I have no reason to think that light therapy is dangerous,” he says.
Research conducted too recently to be included in Golden’s review confirms that light therapy can effectively treat mood disorders, says psychologist Michael Terman of Columbia University. Terman and other researchers studying treatments based on biological rhythms describe their findings in an upcoming Psychological Medicine.
They report that a night of sleep deprivation, like light therapy, is a quick-acting antidepressive. In some tests, nearly two-thirds of people with major depression feel much better within hours of staying awake for a whole night or even for just the second half of a night, Terman and his colleagues say.
Other investigations suggest that a night of sleep deprivation and a gradual return to a full night’s sleep over the next week, combined with daily bright-light exposures, speeds recovery in people receiving antidepressants for major depression or bipolar depression.
To reap maximum long-term benefits, notes psychiatrist David Avery of the University of Washington School of Medicine in Seattle, depressed people receiving light therapy need to sleep on a regular schedule, thus steadying their biological clocks.