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date: 12/21/2005
Shedding light on winter depression helps you make better health decisions every day. We take no advertising from drug companies or the health-care industry—our only interest is in protecting the health and safety of you and your family.
Snow, ice, frigid temperatures, short days, and long, dreary nights are enough to make anyone feel down during the winter months. But each year an estimated 4 to 6 percent of Americans—three-quarters of them women—suffer from more than a simple case of the winter blues. They have seasonal affective disorder, or SAD, a recognized form of clinical depression.

Some symptoms of SAD are like those of other types of depression: feeling unhappy, sleeping more than usual, having trouble concentrating, and withdrawing from others. But SAD sufferers often move slowly, crave carbohydrates, and gain weight. In contrast, depressed people usually lose weight, tend to feel worthless and guilty, and might even consider suicide.

Triggers for the two conditions differ. Episodes of depression can be sparked by a traumatic or stressful situation and can flare up in any season. SAD is seasonal, starting in September or October and subsiding in March or April.

There are several theories about what causes SAD. One is that the level of serotonin—a mood-regulating brain chemical—may drop during the darker months in susceptible individuals. Another is that people with SAD produce more melatonin, a sleep-inducing hormone secreted when it's dark. It's also possible that shorter days trigger a shift in SAD sufferers' circadian rhythms, which regulate the sleep-wake cycle.

One way to determine whether your symptoms signal SAD is to consult a health-care professional, ideally someone with expertise in winter depression. The nonprofit Center for Environmental Therapeutics ( lists major light-therapy research centers where you can find an expert. A confidential online questionnaire at that site can help you determine if you have SAD and can try treating yourself or if you should consult a mental-health professional for treatment of regular depression.

Bright-light therapy, which helps reset the body's internal clock, is generally the best option for treating SAD, says Michael Terman, Ph.D., director of the Center for Light Treatment and Biological Rhythms at Columbia University Medical Center in New York. While antidepressant drugs may be comparably effective, light therapy has two distinct advantages. People generally respond to light in four to seven days versus four to six weeks with antidepressants. And the side effects of bright light—such as eyestrain, headache, nausea, agitation, and insomnia—are generally milder and briefer than those of medication, Terman says. Side effects of the light can usually be reduced by adjusting the intensity, timing, or duration of exposure.

The treatment involves sitting in front of a light box for about 30 minutes a day. Light therapy seems to work best if done within about 10 minutes of waking.

However, about half of SAD sufferers don't respond. Using a light box for half an hour every day, starting with the first signs of SAD and continuing until spring, might not mesh with a busy schedule. And people who have light-sensitive skin or increased risk of retinal disease, or who take medication that interacts with sunlight should consult a dermatologist or ophthalmologist.

SAD sufferers who want or need an alternative to medication or bright-light therapy can try exercise and cognitive therapy. Russian researchers found that 60 minutes of daily outdoor aerobic exercise was comparable to bright-light therapy for easing SAD.

Another study found that twice-weekly sessions of cognitive behavioral therapy for six weeks, alone or together with light therapy, significantly improved SAD symptoms and prevented their return the next year. In addition to exercising and spending time outdoors, strategies learned in those sessions included thinking more positively about winter, trying to socialize more, installing brighter lights in the house, and following a regular sleep schedule.

If you have SAD:

  • First try spending more time outside, particularly walking an hour a day first thing in the morning. Sitting in front of a window may help, too.
  • If those steps don't work, consider bright-light therapy. Choose a light box that's specifically designed to treat SAD and that shines slightly down and delivers white light, not blue. The Society for Light Treatment and Biological Rhythms offers guidelines for such therapy, and its Web site ( lists companies that sell light boxes, which cost $200 to $500 or more; persuading your insurer to reimburse you may take some persistence. Check the manufacturer's trial offers and return policies.
  • If you have severe symptoms or if light therapy doesn't work, causes persistent side effects, or is too risky for you, consult your physician or a mental-health professional.
Terman M, Terman JS. "Light therapy for seasonal and nonseasonal depression: Efficacy, protocol, safety, and side effects," CNS Spectrums, August 2005, pp. 647-63.

Wirz-Justice A, et al. "Chronotherapeutics (light and wake therapy) in affective disorders," Psychological Medicine, July 2005, pp. 939-44.

Golden RN, et al. "The efficacy of light therapy in the treatment of mood disorders: A review and meta-analysis of the evidence," American Journal of Psychiatry, April 2005, pp. 656-62.

Miller AL. "Epidemiology, etiology, and natural treatment of seasonal affective disorder," Alternative Medicine Review, March 2005, pp. 5-13.

Rohan KJ, et al. "Cognitive-behavioral therapy, light therapy, and their combination in treating seasonal affective disorder," Journal of Affective Disorders, June 2004, pp. 273-83.

Benedetti F, et al. "Morning light treatment hastens the antidepressant effect of citalopram: A placebo-controlled trial," Journal of Clinical Psychiatry, June 2003, pp. 648-53.

Wehr TA, et al. "A circadian signal of change of season in patients with seasonal affective disorder," Archives of General Psychiatry, December 2001, pp. 1108-14.

Pinchasov BB, et al. "Mood and energy regulation in seasonal and non-seasonal depression before and after midday treatment with physical exercise or bright light," Psychiatry Research, April 2000, pp. 29-42.

Jepson TL, Ernst ME, Kelly MW. "Current perspectives on the management of seasonal affective disorder," Journal of the American Pharmaceutical Association, November-December 1999, pp. 822-9.

This article was first published in the December 2005 issue of Consumer Reports on Health.

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