Winter begins on December 21, but the time of seasonal affective disorder (SAD) is already under way. SAD is a type of depression that begins in late fall and early winter and usually abates in spring. The exact cause of SAD is unknown, but researchers believe lack of sunlight is the primary contributor.
"SAD is not a minor condition, but because people typically experience it only during certain months, they don't see it as serious," says Dr. Richard Schwartz, associate professor of psychiatry at Harvard-affiliated McLean Hospital. "People should not ignore the signs of SAD and should seek treatment if they appear, as left alone, SAD can escalate to serious health issues."
Your brain on light
Sunlight exposure stimulates the hypothalamus, a part of the brain that houses the body's internal 24-hour sleep-wake clock. Lack of light can throw off this clock. This can cause your brain to produce too much of the sleep hormone melatonin and to release less serotonin, the feel-good brain chemical that affects mood. The resulting chemical imbalance can cause you to feel low, lethargic, or depressed most days.
Other common symptoms of SAD include lack of sexual desire, an urge to overeat (especially high-calorie comfort foods), and problems sleeping. SAD is also associated with impaired cognitive function, including problems with concentration and memory. "As you become more lethargic from SAD, you also are less likely to exercise or socialize," says Dr. Schwartz.
Several factors can raise your risk for SAD. One is a family history of SAD or depression. Another is geography: people who live in northern states, where there's noticeably less light in fall and winter, tend to suffer more from SAD than those living in the south.
Light therapy and antidepressant medications are the two main treatments for SAD. The most effective therapy combines both approaches.
Commonly prescribed drugs for SAD include a selective serotonin reuptake inhibitor (SSRI), such as fluoxetine (Prozac) or sertraline (Zoloft), or a different type of antidepressant called bupropion (Wellbutrin).
Bright light therapy uses light boxes that emit 10,000 lux (a measure of light intensity), about 100 times brighter than usual indoor lighting. For comparison, a bright sunny day is 50,000 lux or more. Light boxes aren't regulated, so buy one that meets certain specifications. Dr. Schwartz recommends checking out the Center for Environmental Therapeutics, a nonprofit organization that does research on light boxes.
To use a light box, place it about a foot away, either in front of you or slightly off to the side. Sit in front of the light for about 30 minutes every morning, as soon as possible after you wake up. Keep your eyes open, but don't look directly at the light. Spend your time reading, writing, or watching TV.
"Try to get in some light before 10 a.m., especially if you often feel SAD symptoms by midday," says Dr. Schwartz. As days become sunnier and sunlight lasts longer during the day, you can use light therapy less often. You may find you can stop during the spring and summer except for extended periods of cloudy weather.
Light therapy is relatively safe, although it can produce some minor, temporary side effects, like headaches and irritability. Also, if you have an eye condition or sun-sensitive skin, check with your doctor or an ophthalmologist prior to starting light therapy.
No light box? You can often get a similar effect from basking in front of a sunlit window or taking an early morning walk. "Keep in mind that light deprivation can affect even the healthiest individuals," says Dr. Schwartz. "So make sure you take steps in winter to get the light your body and brain need."
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