Do you find that your energy flags, your concentration vanishes and your mood droops as winter drags on? Do you crave carbohydrates, such as starches and sweets, sleep more and spend less time socializing as dark mornings and dark afternoons seem to close you in? If so, you may be among the 14 million Americans suffering from seasonal affective disorder (SAD) or the 30 million others who experience a milder version known as the “winter blues.”

SAD and the winter blues aren’t just in your mind. In certain people, reduced sunlight exposure in the darker months triggers significant changes in metabolic functioning. The cause is partly genetic. During the ice age, when food was scarce during the winter months, those with metabolisms that naturally slowed down to conserve energy in winter had an evolutionary advantage.

For their modern descendents, however, this inborn tendency to become sluggish and withdrawn for several months every year is a distinct disadvantage. In the winter, people with SAD find it easy to put on weight and have difficulty concentrating on work and enjoying social activities. There’s also evidence that people with SAD produce increased amounts of insulin in response to increased carbohydrate intake in winter, increasing their risk for diabetes and other ailments.

The good news: Studies have shown that SAD symptoms can be largely reversed by increasing your daily exposure to light.

DIAGNOSING SAD AND THE WINTER BLUES

Virtually everyone is affected by seasonal changes to some degree. People with SAD or the winter blues are simply affected more acutely. You have what’s called winter seasonality if, during the winter months, you feel less happy… eat more and tend to gain weight… socialize less… and sleep more than in other months.

To find out whether this seasonality qualifies as SAD or just the winter blues, rate the degree to which the following aspects of your life change during the winter, on a scale of zero to four. (Zero equals no change… one, slight change… two, moderate change… three, marked change… and four, extremely marked change.)

  • Sleep length.
  • Social activity.
  • Mood (sense of well-being).
  • Weight.
  • Appetite.
  • Energy level.
  • Add up your ratings: A total score of eight to 10 means you may well have the winter blues, while most people with full-blown SAD have scores of 11 or higher.

    LIGHT THERAPY FOR SAD
    AND THE WINTER BLUES

    The single best treatment for SAD and the winter blues is to increase your exposure to light. One way is simply to get outdoors more — by taking a regular morning walk, for example. You can also bring more light into your home or office by increasing the number of light fixtures, painting your walls a lighter color and trimming any hedges or tree branches that may be blocking your windows. A two-week vacation in a sunny climate during winter may also alleviate SAD symptoms to some degree.

    Studies have shown, however, that the most effective solution for people with SAD or winter blues is to sit in front of a specially designed fluorescent light box for 20 to 90 minutes each day. People who use these boxes — which typically cost $200 to $450 — report significant improvements in mood, energy and enjoyment of life within just a few days.

    Selecting a light box: I recommend a “white-light” box (contrary to popular myth, blue-light boxes are not more effective) with a dispersal screen (a plastic screen on the front of the light box that diffuses the light and prevents you from staring at a bright spot) and, because UV rays are potentially harmful to your eyes, a UV filter.

    An effective light box emits between 2,500 and 10,000 lux, a measure of light intensity (normal indoor light is about 500 lux), and should be at least a foot by a foot-and-a-half in size. A good light box can be purchased from these sources…

  • The Center for Environmental Therapeutics (www.cet.org).
  • The SunBox Company (800-548-3968, www.sunbox.com), whose SunRay II ($450) has been tested extensively.
  • Verilux (800-454-4408, www.verilux.com), which makes the HappyLight ($190).
  • Northern Light Technologies (800-263-0066, www.northernlighttechnologies.com).
  • Using a light box: Set the box up in a convenient place where it will shine at head level. Sit within one to three feet of the box for 20 to 90 minutes each day (you can determine the best length of time through trial and error). Sit so that the light falls on your open eyes. You don’t need to stare directly at the box, but the light won’t be effective if your eyes are closed or facing the opposite direction — to receive the benefit, the light must be transmitted through the retina. Finally, try to get your light exposure as early in the morning as possible, since this is when it’s most effective.

    OTHER TREATMENTS

    In addition to light-box therapy, other steps that may help alleviate SAD symptoms include…

  • Regular exercise. Studies show that an hour of daily aerobic exercise, such as walking, running or cycling, is nearly as effective for SAD as light therapy. (Some people do both simultaneously, for example, by pedaling a stationary bike near a light box.)
  • Reducing carbohydrate intake. This will help mitigate the carb-craving (and resulting weight gain) associated with SAD by preventing the carb-triggered increase in insulin production that causes blood sugar levels to drop and cravings to intensify. So, cut back or eliminate your intake of foods such as doughnuts, pizza, sugary soft drinks and candy bars.
  • Sleeping less. Sleeping a lot can make you feel more sluggish. Instead of “sleeping in,” try waking up at seven or eight each morning. Even better: Use a dawn simulator (a timer attached to an ordinary incandescent light) that slowly turns up the brightness over the course of an hour or so. My favorite is the SunUp by Enviro-Med, which plugs into any bedside lamp. Cost: $200 (800-222-3296, www.bio-light.com).
  • WHEN TO SEE A DOCTOR

    Many of these steps, including light therapy, can be taken on your own. You should keep your primary care physician informed about what you’re doing, however. In addition, see a doctor about your SAD symptoms if your sleeping and eating are way off kilter — for instance, if you’re sleeping more than usual and still feel tired… or you’ve been loading up on sweets and starchy food and never feel satisfied… or if you feel seriously depressed (it may be that you also need antidepressant medication, which can be very effective in treating severe SAD symptoms). Finally, counseling with a therapist may also be helpful for SAD-related depression.