SAD most commonly occurs during the fall and winter months when days become shorter, but some people may experience symptoms at other times of the year.
What is Seasonal Affective Disorder?
Seasonal Affective Disorder, also called SAD, is a type of mood disorder which occurs during certain months of the year. People with SAD develop symptoms of depression which include unexplained sadness, irritability, low energy, decreased activity, and tiredness. SAD is similar to major depressive disorder but it is a recurrent condition which occurs during a part of the year. Once the season has passed, symptoms may resolve only to occur again at the same time the following year.
Up to 16 million people in the U.S. may have SAD but in many cases, it may go undiagnosed. Certain groups are more likely to have SAD such as:
- SAD occurs in four times as many women as men
- SAD is more common in young adults between 18 and 30 years of age
- SAD occurs more frequently in northern latitudes and higher elevations
- People with a family history or a personal history of having depression or bipolar disorder are more likely to develop SAD
Most people who have SAD, develop symptoms during the fall and winter months. People who develop symptoms of SAD during the spring or summer months may be said to have “reverse” or summer SAD.
Why do people develop Seasonal Affective Disorder?
Though there is no proven reason why some people develop Seasonal Affective Disorder, it may be due to decreasing light levels and shorter days of fall and winter months and a lack of Vitamin D production. This may produce a difficulty regulating the neurotransmitter, serotonin and an increased production of a hormone known as melatonin.
Serotonin is a neurotransmitter or brain chemical which is responsible for regulating mood and producing a feeling of satisfaction. Melatonin is a hormone that is responsible for sleep regulation. Both of these substances are related to Vitamin D production which is produced in the skin after sun exposure.
Normally, as light levels fall and it becomes darker at night, Vitamin D production decreases, which triggers the body to produce melatonin, causing “sleepiness”. During fall and winter, with decreasing levels of light, overall Vitamin D production may slow and the body may make too much melatonin.
In addition, low Vitamin D levels may decrease the ability for the body to manufacture serotonin. In theory, low levels of serotonin and high levels of melatonin may produce a feeling of sadness and tiredness. When daylight hours become longer and sunlight becomes more direct in spring and summer, the system is returned to normal – alleviating depression.
Summer Seasonal Affective Disorder
Summer SAD is the reverse type of SAD which occurs during summer months. Again, there is no definitive cause but some experts believe it is due to a disruption of melatonin and serotonin production during seasonal change. Some people may lack the ability to adapt easily to changes in circadian rhythm or their “internal clock”, and may respond by becoming depressed.
Seasonal changes in spring and summer including overexposure to sun, high temperatures and increases in pollen count or allergen levels may also contribute to summer SAD.
Diagnosing Seasonal Affective Disorder
Mood disorders are diagnosed with criteria listed in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). The DSM-5 requires that patients must meet the criteria for the major depressive disorder and that the symptoms must occur during the same season every year for at least two years. People who have depression at other times of the year or display symptoms of another mental disorder are excluded from the SAD diagnosis.
To diagnose SAD, patients will generally be asked about their medical history, medication use and, given a physical exam with laboratory testing to rule out medical causes for depression such as thyroid disorder. They will usually be required to complete a number of written questionnaires and given an in-depth interview to asses the specific symptoms and determine a pattern to the disorder.
Symptoms of Seasonal Affective Disorder
SAD symptoms are the same as symptoms of major depression including:
- Unexplained or excessive sadness
- Anxiety and irritability
- Excessive worry
- Feelings of guilt
- Decreased activity
- Loss of interest in normal activity
- Fatigue and lethargy
- Daytime tiredness
- Sleeping difficulties
- Overeating or undereating
- Lack of concentration
- Withdrawal from social activities
Treating Seasonal Affective Disorder
Like other types of depression, Seasonal Affective Disorder is often debilitating. Most patients will benefit from one or more types of treatment, used in combination.
Therapy – No matter what the cause, people with depression will often benefit from “talk therapy”. Therapy sessions with a professional who is trained in psychology or counseling may be done on an individual basis or in a group with others who have similar symptoms. Cognitive Behavioral Therapy (CBT) has been shown to be useful in treating SAD and helps to improve mood state by positive reinforcement.
Medication – Antidepressants, particularly the Selective Serotonin Reuptake Inhibitors (SSRI) medications may be used to increase serotonin levels in the brain. Some patients may also benefit from different types of antidepressants or from short-term use of antianxiety agents.
Light therapy – When SAD occurs during winter months, the use of light or phototherapy may help to improve mood states. Patients are asked to sit in front of or under a light box which contains a specific type of bulb to simulate sun exposure. In many cases, light therapy done in the mornings for 20-60 minutes every day from early fall to spring may help alleviate symptoms or reduce the severity for the next season.
Sun exposure – Patients are often encouraged to get out in the sun when possible during winter months. Lack of exposure to sunlight and reduction of Vitamin D production is thought to be related to the development of SAD. Getting outside or ensuring that window coverings are opened during the day may help reverse or reduce symptoms of SAD.
Exercise – SAD both encourages and is worsened by fatigue and lack of activity. Physical activity can help alleviate the symptoms and patients are encouraged to participate in routine exercise. Most experts recommend 30 to 60 minutes daily, five or more days per week of moderate exercise that may be aerobic or strength training. If exercise is performed outside, it may be more beneficial.
People with signs of Seasonal Affective Disorder or other depression should be encouraged to consult with a physician or mental health professional about their symptoms and treatment options.