For millions of Americans, the winter months can literally become a “SAD” time. Seasonal Affective Disorder (SAD) affects about 10 million people with symptoms of clinical depression that seem to be triggered by the colder, darker months. SAD is more than a case of the winter blues. SAD can be a debilitating condition that is just as severe as serious deep depression.

SAD is a form of a recurrent depressive or bipolar disorder characterized by a seasonal pattern of onset and reduction. This differs from other types of depression because it is directly linked to seasonal changes. Usually, SAD begins in early winter and dissipates by spring or summer.

Studies show that 4-6 % of the population suffers from severe winter depression and that another 20% have mild winter depression. The disorder also may be genetically related to other forms of affective illness. For example, more than two-thirds of SAD patients have a close relative who suffers from a major affective disorder such as depression or bipolar. Women experience SAD four times more than men, affecting women between the ages of 20-40. While seen across all age groups, SAD generally isn’t seen in people younger than 20.

The incidence and severity of SAD seem to increase the farther people live from the equator. SAD is more common in the northern hemisphere where the day are shorter. For example, SAD is seven times more prevalent in the state of Washington than it is in Florida. This disorder also affects those in closed environments or who work rotating or off-shift work.

Scientists have long known about and studied the body’s circadian rhythms. This internal biological clock controls hormones, body temperature sleep-wake cycle, appetite, and other bodily functions independent of what the clock hanging on the kitchen wall says. That’s why it takes people a few days to adjust to daylight savings time or why some suffer from jet lag when they travel across time zones. Sunlight is a very important cue for setting and regulating the body’s circadian internal clock. For a person with SAD, his or her internal clock is very sensitive to the decreases in sunlight that occur during the winter. In a person with SAD, the body’s internal mechanism gets more out of sync with the clock on the wall, leading to serious consequences.

Lack of sunlight and vitamin D during the winter months can cause the body to over produce melatonin, a sleep hormone, leading to extreme fatigue, depression and desire to compensate for lack of energy by eating more carbohydrates for fuel. It also decreases the serotonin production that identifies the chemical in the brain that plays a major role in sleep, mood, appetite, depression, and sometimes leads to radical mood swings.

Diagnostic criteria includes a regular relationship between onset and disappearance and at least three episodes of mood disturbance in three separate years that demonstrates this waxing and waning onset of the disorder. Also, seasonal episodes of mood disturbance should outnumber any non-seasonal episodes by more than 3 to 1. Diagnosis of SAD also requires a pattern of seasonal depression over at least two consecutive winters followed by recovery in the spring or summer. Incidents of seasonal depression must also far outnumber incidents of non-seasonal depression.

Symptoms of SAD typically peak in January and February and start to dissipate as spring approaches. Symptoms recur at about the same time every year. Not everyone experiences the same symptoms but the most common include:

• change in appetite, cravings for sweets or carbohydrates
• significant weight gain (10-20 pounds)
• heavy feeling in arms and legs
• constant fatigue with low levels of energy
• tendency to oversleep with long periods of naps
• difficulty concentrating
• intentional social withdrawal
• eyestrain or headaches
• overwhelmed feeling with simple tasks
• loss of interest in activities you once enjoyed
  decreased libido

Some people’s symptoms become so severe that they must be hospitalized. Most people, however, can be treated effectively on an outpatient basis. Fortunately, SAD is usually very treatable so people should seek help before the depression becomes unbearable. Now that doctors are beginning to understand more and more about this disorder, there is hope for even the darkest cases of the winter blues.

The most effective form of treatment for SAD is light therapy. This works by exposing the patient to bright light or sunlight for 30 minutes or longer in the early morning. Light intensity is expressed in units of lux. Indoor lighting is typically under 500 lux. Outdoor light on a cloudy day is 1000-5000 lux. Mid-day summer light can reach 50,000 lux or higher. Light therapy utilizes 2500 lux for at least one to two hours each day. There is similar efficacy for 30 minutes at 10,000 lux exposures. Although positive effectives have been achieved at much lower levels, brief high intensity light treatments are much more easier to schedule into the day than the longer, dimmer sessions. Morning treatments are much more effective than evening.

When a doctor suggests light therapy, the patient uses a special light box or visor that delivers a predetermined level of light brightness. SAD symptoms appear to subside after three to five days of light treatment, but two weeks of therapy may be required before an optimal response is achieved. The symptoms may recur in 3-4 days following discontinuation of treatment. Light therapy is safe when conducted under a doctor’s supervision. Potential side effects can include: eyestrain, headache, fatigue, irritability, and insomnia. Too much light or looking directly into the source light can cause eye damage. Tanning lights should never be used for light therapy. Light therapy regimens are not considered harmful to the human retina based on short-term studies, but long-term effects are not yet known.

The good news is that even though SAD is relatively new in terms of scientific research, specialists have quickly made significant treatment options even if they don’t fully understand why some people are more profoundly affected by seasonal changes. If you think you are suffering from the winter blues, here are some easy steps to take on your own:

• Spend more time outside. Even an overcast day is brighter than the best lit office or home.
• Exercise outside because it will help fight feelings of lethargy and help fight weight gain.
• Take a 20-minute walk in the morning or at lunchtime for an energy boost.
• If indoors, spend more time in front of windows and allow as much natural light in as possible.
• Eat a balanced diet. Don’t overload on carbohydrates. Too many carbs lead to lethargy.
• If possible, plan a winter trip to a sunny place.

For more information on sleep and sleep disorders, check out the National Sleep Foundation's Web Site at www.sleepfoundation.org