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Lightening the Winter Blues

Every winter Lois falls into a deep depression. As the days grow darker and nights longer, she can't seem to get out of bed. She's tired, moody, and unable to focus at work. But come summer she is a different person. She swims three times a week, sees friends, and is highly productive. Like 10 million other Americans, Lois suffers from seasonal affective disorder, better known as SAD. An additional 25 million Americans may have a milder form of the condition.

For Lois, living in the Northeast, where winter days are shorter, doesn't help. Less sunlight can trigger other SAD symptoms, including cravings for sweets and carbohydrates, weight gain, loss of libido, and even despair. Studies suggest that up to 80% of sufferers are women, most of whom start experiencing symptoms in their twenties and thirties. Although women are more likely to get help for the condition, many men and children also suffer from SAD. The disorder may also run in families; at the National Institute of Mental Health, scientists recently discovered a gene that may make people prone to the condition by affecting their response to light.

A new survey by University of Massachusetts researchers of 600 members of a large HMO found a "clear seasonal effect" on mood. Depression was highest in the winter and lowest in the summer, while autumn and spring fell in between. In addition to depression, levels of anger, hostility, irritability, and anxiety were also higher in the winter.

Resynchronizing the Body's Internal Clock
Waning winter light appears to cause SAD in susceptible people by disturbing the body's natural clock. "People with SAD experience something like continual jet lag," says David Avery, M.D., a professor of psychiatry and behavioral sciences at the University of Washington School of Medicine in Seattle. "They wake up feeling as though it's the middle of the night. And our data suggest that physiologically, for them, it is the middle of the night." Intense artificial light appears to reset the body's internal clock, thereby easing symptoms. The response may have something to do with the brain chemical serotonin, the hormone associated with wakefulness and an elevated mood. People suffering SAD may be low in serotonin, and bright light appears to boost levels of the hormone.

Our body’s response to light is indeed a thing of beauty. In the brain, a cluster of nerve cells called the suprachiasmatic nucleus (SCN) depends on light from the outside world to keep time inside us. The SCN even registers the faint dawn light that filters through our eyelids as we sleep. A burst of light in the morning sets the inner clock ahead, and a burst in the evening sets it back. In a recent study of 124 patients with winter depression, Michael Terman of the Columbia-Presbyterian Medical Center in New York found that 60% of those exposed to bright light in the morning improved, but only 30% responded to light treatment in the evening.

Light Therapy
Although exercise, antidepressants, and psychotherapy may help ease SAD, light boxes and other light-emitting devices often get results as well. Dr. Clifford Taylor of the University of Medicine and Dentistry of New Jersey has found that many of his SAD patients who use light therapy can lower their dose of standard antidepressant drugs. The treatment also appears to be very safe (some people get a jittery feeling or suffer from headaches or eye strain if light intensity is too bright). Unlike the machines used in tanning parlors, light devices for SAD do not emit UV rays, so you won’t get sunburned or develop cataracts from using them. Nor do the treatments interact with drugs or herbs (such as St. John's wort) that may increase sensitivity to sunlight.

Scientists at the University of Helsinki in Finland have even shown that greater exposure to summer sun may help lift your mood months later during the winter. The link here appears to be vitamin D. Exposure to light buoys production of a compound called cholecalciferol, which the body changes into vitamin D. This process in turn helps maintain serotonin levels during the following months.

But Norman Rosenthal at the National Institute of Mental Health, a pioneer in SAD research as well as a sufferer himself, believes that although early light therapy often keeps depression from becoming severe, treatment almost always needs to be continued throughout the season to prevent a relapse. He also believes that "it is beneficial to start light therapy as soon as the first symptoms of winter depression occur."

In addition, light therapy can be safely combined with other therapies for SAD. The WHMD Advisor's chief medical consultant, Dr. David Edelberg, uses various supplements to treat symptoms of SAD. These include melatonin (1 to 3 mg before bedtime) for insomnia; St. John's wort (300 mg three times a day) for depression; and 5-HTP (50 to 100 mg three times a day) to boost brain serotonin levels. Stress reduction techniques, regular exercise, and a diet low in carbohydrates may also help.

Suggested dose: Light therapy normally includes exposure to artificial light for 20 to 30 minutes every morning. Some people respond within three or four days; others need as much as four weeks.

Further reading: Norman E. Rosenthal, M.D., Winter Blues: Seasonal Affective Disorder: What It Is and How to Overcome It (Guilford, 1998) (www.normanrosenthal.com); Clifford Taylor, M.D., If You Think You Have Seasonal Affective Disorder (Dell, 1998)


Date Published: 06/24/2001
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