Many people around the world have depressive episodes during specific seasons. Those who have minimal mental health issues throughout the rest of the year may experience symptoms of depression during a single season. In 1984, Norman Rosenthal described and named this depression seasonal affective disorder or SAD. He also pioneered light therapy as an effective means of treating the symptoms. Many people initially disagreed with the existence of seasonal affective disorder, though now it appears as a mood disorder subset in the Diagnostic and Statistical Manual of Mental Disorders, the DSM.

Updated Definition

Since its discovery in 1984, experts have debated the existence of SAD. Some people believed the depressive symptoms experienced during winter were not proof of a disorder but rather that the dark and cold weather set the expectation of being sad. However, studies confirm the symptoms exist and affect people during any season. Certain individuals may experience the symptoms during spring or summer rather than fall and winter. The fourth and fifth editions of the DSM define SAD as a mood disorder subtype and recommend it as an added descriptor for 2people who experience a pattern of major depressive episodes or patients with bipolar disorder.

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Symptoms of Major Depression

Those with SAD experience symptoms associated with major depressive disorders. Feelings of worthlessness and hopelessness are common, with thoughts of suicide frequently appearing as well. Many people lose interest in activities that interested them previously and may avoid social interactions. Some people may feel as though they lack the energy to perform seemingly easy tasks, which can lead to an increased feeling of failure.

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Symptoms of SAD

Though SAD shares many symptoms with major depression, it does have a few unique issues. Those with SAD episodes during winter may oversleep, gain weight, and experience nausea. Some people report cravings for carbohydrates. Springtime SAD episodes appear with opposite symptoms. Off-season spring and summer SAD frequently cause insomnia, loss of appetite, and agitation. This agitation may lead to an increase in violent actions or behavior. Loss of appetite usually results in significant weight loss.

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Risk Factors

Certain qualities seem to increase the risk of SAD. Upwards of 20% of people who have depression or bipolar disorder receive a diagnosis of SAD. Doctors find women are four times more likely to have it than men. Children, teens, and young adults also receive the diagnosis more often than older individuals. Countries further from the equator have higher diagnosis rates than more equatorial regions. SAD affects around one percent of people in Florida while it affects upwards of nine percent in New England or Alaska.

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Though experts haven't determined the exact cause of SAD, the apparent greater chance of it developing in women may mean the condition is related to the regulation of reproduction. This may also explain why it appears more often in teenagers and young adults. Their bodies have most recently undergone puberty, and the development of hormones for sexual reproduction may trigger SAD. Some experts believe the reduction of sunlight triggers an evolutionary response similar to hibernation. Certain personality traits may also be responsible for SAD. High levels of neuroticism, openness, and agreeableness appear to correlate directly with SAD.

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Light Therapy

The predominance of the theory that a lack of natural light causes SAD episodes led to light therapy treatment. A study in 2000 found that bright lights in the workplace dramatically reduce the effects of SAD in workers. The employees reported increased energy, alertness, and productivity, as well as a subjective increase in mood. Many doctors use light therapy to treat SAD symptoms because they prefer to avoid prescribing medication until all other options are exhausted.

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Vitamin D

Doctors found many people experiencing symptoms of SAD have low levels of vitamin D in their blood. The body forms vitamin D when direct sunlight converts chemicals in the skin. By ensuring access to enough vitamin D, an individual can reduce their risk of developing disorders such as multiple sclerosis and osteoporosis. Some studies show vitamin D supplements can also help prevent or reduce the severity of depressive symptoms. Doctors may pair these supplements with light therapies for maximum effectiveness.

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For people with extreme depressive symptoms, doctors may prescribe antidepressants, which aim to correct the chemical imbalances in the brain that are responsible for the feelings of hopelessness and other symptoms. The most commonly prescribed medications affect the amount of serotonin the brain. Serotonin usually acts as a mood stabilizer, so higher levels correlate with fewer depressive symptoms. By blocking the absorption of serotonin, antidepressants increase the amount of serotonin in the brain.

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Cognitive Behavioral Therapy

Some professionals believe that through challenging the thoughts and attitudes of depression an individual can improve their mental health. Symptoms of depression often involve the magnification of negatives and minimization of positives. Therapists help clients walk through the steps of recognizing this, and then guide individuals through combatting it healthily. Behavioral therapy also helps people experiencing anxiety, schizophrenia, body dysmorphia, and many other psychological and mood disorders.

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An effective form of depression therapy, exercise releases proteins called growth factors that cause nerve cell growth. This improves brain function, which leads to improved mood. Some studies combine exercise with light therapy by adding exercise bike routines to generic UV light treatments. This combination treatment dramatically reduced the symptoms of SAD and showed a marked improvement in subjects' moods. The overall recovery time for the depressive episode also declined.

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