For the millions of Americans who suffer from mild to severe winter blues — a condition called seasonal affective disorder, or S.A.D. — bright-light therapy is the treatment of choice, with response rates comparable with those of antidepressants. “Your natural clock is usually longer than 24 hours, and you need light in the morning to set it and keep it on track,” said Dr. Alfred Lewy, a professor of psychiatry at Oregon Health and Science University and an expert on seasonal depression and light therapy.
Yet many experts think light therapy is underused, given its affordability and relative lack of side effects, in large part because there is little profit to be made from it and no commercial incentive to promote the treatment.
Patients generally sit in front of the light box, which can be as small as 9 by 11 inches and 5 inches deep, with the bright light emanating from the square surface, in the morning. “With the natural dawn being later in winter, the body rhythms drift late,” Dr. Lewy said. “If you can fix the drift, you can fix the depression.”
Light therapy may even help with major nonseasonal depression, experts say, and withsleep disorders. And because it has few side effects, researchers are studying whether light therapy can help with depression during pregnancy and be used to treat elderly people with dementia. It is also being investigated for the treatment of bulimia nervosa, severe premenstrual syndrome and even attention deficit hyperactivity disorder and bipolar disorder.
Though randomized controlled clinical trials of bright light are difficult to do properly — one expert is fond of saying that it is difficult to “blind” studies of bright light — the American Psychiatric Association considers bright-light therapy an effective low-risk treatment for both S.A.D. and nonseasonal major depressive disorder.
A 2006 multicenter double-blind randomized controlled trial that compared bright-light therapy head to head with the popular antidepressant Prozac (fluoxetine) in 96 subjects found the two treatments equally effective for alleviating winter depression, though light produced results faster, usually within a week, and with fewer side effects.
Why, then, do so few doctors prescribe bright-light therapy? Some say their patients don’t have the patience to sit in front of a light for 30 to 45 minutes every morning. Moreover, “doctors are just more comfortable prescribing medication, because that’s what they do for everything,” Dr. Lewy said.
Some patients who suffer from chronic depression say they use light therapy in addition to their regular medication in the winter months.
“I’ve always seen a drastic change in my personality from spring and summer to fall and winter, and it got worse as I got older,” said Rick Bach, 54, a painter who owns a hair salon in West Hartford, Conn., and tries to spend every January in Puerto Rico.
But while bright-light treatment is helpful, he said, it is not sufficient for him. “It can help you from falling into a deep depression, but it won’t help you climb out of one,” he said.
No one knows exactly how light treatment works, but most experts seem to agree that the body has a master biological clock that responds to or is “set” by natural light fluctuations.
“Light does more than just enable us to see,” said Dr. Norman Rosenthal, author of the landmark book “Winter Blues,” who was among the first to identify and describe S.A.D. Light also has an effect on hormones, the body’s chemical messengers, affecting the brain’s hypothalamus, which is involved in regulating mood, energy and appetite.
“The hormone melatonin, which is secreted at night, can be suppressed by light,” Dr. Rosenthal said. “Studies have also shown that light influences serotonin and epinephrinepathways in the brain, the same neurotransmitter systems known to be affected in people with general depression.”
But while part of the appeal of light therapy is that it can be self-prescribed, using a light box is not as simple as it may appear. Experts recommend consulting with a knowledgeable health care provider before starting treatment to rule out other medical conditions and to help with monitoring and adjusting bright-light exposure.
Some patients may want to try simply getting more natural light to help with seasonalmood changes — getting out as much as possible during the brightest time of day in the winter, sitting near windows during the day or taking vacations to sunny locales in the winter.