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Seasonal Affective Disorder: When Winter Turns Your Mood to the Dark Side

Just as plants need light to stay green, humans need light to stay healthy. The shorter days of autumn and winter provide us with less sunlight, and that can play havoc with our internal clocks. These “clocks”—actually, our circadian rhythms—regulate our sleeping and waking, body temperature, hunger, balance of body fluids, and psychological functions.

To add to the effects of shorter days, scientists are now communicating figures for what they are calling “global dimming”. In a study of the past five decades they have noticed a 22% drop in sunlight. This phenomenon is said to be caused by air pollution.

Unfortunately, we can’t set our body clocks forward or backward according to Daylight Saving Time, nor can we control the output of pollution by our neighbors, even still, some people have trouble adapting to the seasonal change growing effects of pollutants. For these folks, the response to diminished daylight hours is a mood disorder called seasonal affective disorder, often better known by its appropriate acronym, SAD. An estimated 25 percent of the American population is mildly affected by SAD, and another 5 percent is seriously affected.

The winter of our discontent
Seasonal affective disorder was first identified in 1984 by Norman Rosenthal, M.D., researcher at the National Institute of Mental Health. He noted that SAD mimics depression in its symptoms, but with a certain distinction: SAD symptoms begin in autumn as daylight hours start dwindling, peak in January or February when daylight hours are shortest, then dissipate as spring approaches.

Most who endure freezing winters experience cabin fever, sleep more, and eat more. But SAD symptoms go far beyond the winter doldrums (see sidebar “Typical SAD Symptoms”). SAD is probably to blame when symptoms appear for at least two consecutive winters, yet are absent during spring and summer months.

Take SAD seriously. Many SAD sufferers have weakened immune systems, making them more vulnerable to infection and illness. At its worst, the disorder is debilitating, preventing sufferers from functioning normally.

The science of SAD-ness
What exactly causes SAD? There is no clear-cut answer, but the following three theories seem most plausible:

• Too much melatonin
  The hormone melatonin, a brain chemical (neurotransmitter) that makes us sleepy, is thought to also cause symptoms of depression. Because the melatonin in our blood peaks between dusk and dawn, longer winter nights may allow for its overproduction.

• Too little serotonin
  Deficiency of serotonin causes depression, and production of this neurotransmitter hits bottom in the winter.

• Eye abnormalities
  The eyes of SAD patients may not adjust to dim winter days as well as those of their non-suffering peers. This can fool the body into thinking the short daylight hours are even shorter.

Two blues brothers
Full-fledged SAD has a milder but more common relative, known as “subsyndromal SAD” or “winter blues.” It shares most of SAD’s symptoms, except for depression and anxiety.

Also related to traditional SAD is its seasonal opposite, called “summer SAD,” “summer depression,” or “reverse SAD.” This condition waxes in the spring and summer, then wanes in the fall and winter. Characteristics include depression, poor appetite, weight loss, insomnia, and feelings of hopelessness.

Who is a SAD candidate?
Your chances of getting SAD increase the farther north you live from the equator. Studies show that only 1 percent of Floridians suffer from SAD, compared with 10 percent of New Hampshire residents. Averaging 226 cloudy days per year, notoriously overcast Seattle produces only a few weeks of sunny winter days—an environment ripe for SAD. And in coastal cities like San Francisco, continual fog can spawn widespread SAD among residents.

If you have a night job and sleep during daylight hours, or if your job or routine keeps you out of the sunlight, you’re more prone to developing SAD. Genetics, heredity, stress, and a body’s chemical make-up also may play a role.

Anywhere from 60 to 90 percent of SAD patients are women, perhaps because of their greater susceptibility to depression. Most sufferers are in their 20s, 30s, and 40s. Some outgrow their SAD condition; others must cope with it for a lifetime.

How to lighten up
If you suffer from SAD, you may be able to minimize your symptoms by changing your environment or lifestyle:

• Intensify the natural light that enters your home by adding skylights, and trimming branches that block light.
• Sit by a large window in the morning, even on cloudy days.
• Walk outdoors in winter sunlight for at least 30 minutes daily.
• Engage in other regular exercise (especially outdoors) to alleviate stress and anxiety, which can aggravate SAD.
• Take winter vacations to sunny locales, if possible.
• Resist the temptation to stay up late at night and sleep late in the morning.
• Go to bed and wake up at specific times to help your body reset your internal clock.

Severe cases of SAD may require treatment with antidepressants, counseling, light therapy, or a combination of these. Antidepressant drugs can dispel SAD but may have side effects. Counseling can teach the sufferer to cope with and prevent symptoms. Light therapy, which involves bright light as a remedy for winter gloominess, halts the flow of melatonin and raises blood levels of serotonin.

Looking on the bright side
Light therapy, also called phototherapy, has its roots in ancient customs. Dr. Rosenthal notes that many cultures celebrate major holidays near the year’s shortest day, and that such celebrations involve lighting candles.

In modern times, light therapy often uses white fluorescent lights mounted on a metal reflector and shielded with a plastic screen. SAD patients soak up artificial rays in front of such “light boxes” for a specified amount of time each day—anywhere from 30 minutes to three hours—while they work, eat, or watch TV. The key is to keep the light box in one’s peripheral vision.

Between 60 and 90 percent of patients notice a difference after two to four days of light therapy. Their symptoms generally lessen after three weeks of treatment.

Light therapy requires the right amount of brightness (often 2,500 to 10,000 lux). Side effects can include headaches, eye strain, and nausea. Those with sensitive eyes or skin should not use light therapy. Therefore, a physician should be consulted before such treatments.

So what about you? Do your moods, energy, and quality of life take a nosedive every winter? Don’t let blues color you. Seek professional help to recapture your well-being and restore your sunny disposition.