Seasonal affective disorder

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at March 30, 2016
StartDiseasesSeasonal affective disorder

For many, the change in seasons can cause a severe change in mood and overall mental health. This change is often associated with a common type of depression tied to the seasons known as seasonal affective disorder or SAD.


Definition & Facts

Seasonal affective disorder presents as a change in mood that is directly correlated to the available amounts and strength of sun exposure. An estimated 10 million Americans suffer from this disorder each year, and an additional 10 to 20 percent of the population experiences some mild form of the condition during periods of the year with less sunlight.

While SAD can develop in children, it's rare to see symptoms developing in those under the age of 20. The condition is also much more common in men than women. In rare cases, the seasons involved in SAD may be reversed, also known as summer-onset seasonal affective disorder or summer depression. In this variation, the symptoms develop in the warmer months of the year.

Symptoms & Complaints

As a form of depression, seasonal affective disorder has symptoms that are identical to major depression, as well as symptoms that are more common to SAD. More unique symptoms include a change in appetite and cravings, which leads to a higher carbohydrate intake and often weight gain.

Chronic low energy and tiredness combined with oversleeping are also common. During this time period patient's may also experience irritability and a more difficult time getting along with others. Generally symptoms appear in late fall and start to dissipate by late spring. Symptoms may also worsen during the deepest parts of winter as sun exposure is at its lowest point.

Symptoms can become severe and even life-threatening when they include feeling hopeless, feeling depressed on a daily basis, feeling worthless, stopping activities and hobbies that are typically enjoyed, isolating oneself from others or having frequent thoughts about death or suicide.


There is currently no known single cause for developing SAD, but there are several theories as to why symptoms may develop. A primary theory revolves around a drop in serotonin levels. Serotonin is a neurotransmitter that helps regulate a person's mood and is often referred to as a "feel good" chemical. The brain produces more serotonin on sunny days than on darker days, which may explain the difference in mood during the winter.

Another chemical that may be involved in causing SAD is melatonin. Abnormal levels of this hormone that is released by the pineal gland have been observed in people with seasonal affective disorder as well as bipolar disorder. The timing of when melatonin is released may also play a role.

A person's internal clock can also contribute to symptom development. This clock is more scientifically referred to as circadian rhythm, and the changes in sunlight availability during the winter can throw this clock out of rhythm, resulting in symptoms of depression.

Diagnosis & Tests

When diagnosing SAD, a doctor may perform a variety of both physical and psychological tests. Diagnosis often starts with a physical exam. During this exam, the doctor will ask a variety of questions to help determine both personal history and family history. They will also perform a variety of physical examinations to ensure that symptoms are not being caused by other underlying health conditions.

A common condition that can mimic symptoms of SAD is an improperly functioning thyroid gland. It's not uncommon for doctors to request a blood test for a complete blood count lab testing to ensure the thyroid is working efficiently.

Once the physical examination has been completed, psychological testing can be used to determine whether the symptoms match the DSM-5 criteria for seasonal affective disorder. To meet this criteria, seasonal symptoms must occur over at least the last two years and include depression that starts during one specific season and ends during another. There must also be no depression symptoms during the rest of the year.

Treatment & Therapy

Treatment for SAD is available in three main forms. The first is through light therapy or phototherapy. This treatment involves a therapy light box that uses a bright light to mimic the light of the sun. It may take a few days to a few weeks for light therapy to start reducing or eliminating symptoms. Those suffering from the condition should also take steps to make the home brighter by keeping shades and curtains open when indoors, and finding time to go outside in the natural daylight as often as possible.

For those that suffer from more severe cases of this disorder, medications may be utilized starting a few weeks before symptoms typically start to develop. Starting early allows time for the medication to establish itself in the body. The medication can then be stopped around the time symptoms typically let up. Common medications for this purpose include, Aplenzin® and Wellbutrin XL®, both of which are extended-release versions of the antidepressant bupropion.

Psychotherapy can help manage symptoms and is especially helpful for cases where self harm or suicidal thoughts are present. Psychotherapy helps patients cope better with stress, teaches coping mechanisms for living with and overcoming depression symptoms, and works to change the negative thoughts that lead to unhealthy or unsafe behaviors during episodes of SAD.

Prevention & Prophylaxis

Currently there is no way to prevent seasonal affective disorder from developing. While it may not be preventable, those who suffer from SAD can take steps to manage symptoms early in the weeks leading up to a change in seasons to reduce symptom severity. Year-round lifestyle changes for managing general depression may also help reduce symptoms, such as regular exercise, eating healthy foods and taking part in stress-reducing activities like yoga or meditation.