Seasonal affective disorder, or SAD, is a form of depression whose symptoms manifest and disappear with the changing of the seasons. The vast majority of SAD sufferers feel their depression symptoms set in with the coming of winter, and feel them recede again in the spring.
It is generally accepted that this cyclical condition is caused by the reduced exposure to natural sunlight that winter brings, but what is unclear is exactly how or why less sunlight can cause depression. One likely theory is that sunlight contributes to the production of serotonin, a neurotransmitter that induces a calming effect in the brain; less sunlight leads to less serotonin, which in turn leads to depression symptoms.
Common signs of seasonal depression include what some sufferers collectively describe as, not unfittingly, a desire to hibernate: fatigue, lack of energy, increased desire and/or need to sleep, listlessness and lack of interest in activities, withdrawal from social interaction, and overeating and weight gain, with cravings for carbohydrates, in particular. This last symptom supports the serotonin-deficiency theory because carbohydrates facilitate serotonin production.
In more severe cases, sufferers may also be highly emotionally sensitive and have feelings of unshakable sadness and hopelessness, and the intensity of their symptoms can start to interfere with their relationships and normal everyday functioning.
But all of the above symptoms also resemble those of other types of depression — what distinguishes them is their timing and seasonally cyclical onset. If you are experiencing symptoms of depression, your doctor can assess whether SAD is to blame.
Risk Factors for SAD
Anyone can develop SAD — an estimated one-quarter of Americans experience mild symptoms each year. However, some factors that might make you more prone to seasonal affective disorder, or to experience stronger symptoms, include:
Geographical location. Not surprisingly, in North America SAD is more prevalent in northern climates, where sunlight exposure is most greatly reduced during the winter.
Gender. Similar to many other types of depression, SAD affects more women than men.
Age. Seasonal affective disorder occurs largely in adults; it is a much more rare condition for children and teenagers.
Effective Treatment of SAD
Since seasonal affective disorder is brought on by reduced exposure to natural sunlight, it makes sense that the primary means of treating SAD is the daily use, usually for about half an hour each day, of a light source that simulates sunlight. Some people with SAD place a light box or lamp close to them, while others prefer a light visor that they wear on their heads and that “shines down” directly on them. Many people with SAD who work in offices, and who on an average winter workday might not get any natural sunlight exposure at all, have found that using a SAD lamp at their desks does a great deal to lift their spirits.
Still another form of seasonal affective disorder light therapy is a dawn simulator, which is a light kept in the bedroom and that gradually increases in brightness each morning, like the light shining through the window as the sun rises.
However, according to the National Institute of Mental Health, seasonal affective disorder lights alone do not adequately alleviate symptoms in almost half of SAD sufferers. For these individuals, a treatment plan that combines antidepressant medication with psychotherapy sessions, and that may or may not also include light therapy, usually yields better results.