Appledore Medical Group December 20, 2017

by Peter Cook, MD

Seasonal affective disorder (SAD) is a type of depression. It is associated with the seasonal changes in light and may be caused by fluctuations in hormones and brain chemicals. Many people have difficulty dealing with the increasingly darker, shorter days of late fall into winter. They struggle to get out of bed in the morning, have less energy, feel down, and gain weight. For people with seasonal affective disorder (SAD), these changes are severe enough to interfere with normal daily functioning. But what exactly is SAD? And how can it be treated?


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An abnormality in one or more neurotransmitters and/or hormones is the suspected cause of SAD. Some factors that may play a role include:

  • Reduced sunlight—Affects internal biological clocks, and readjusts hormones and brain chemicals. Lack of exposure to light seems to be the main trigger for SAD symptoms.
  • Changes in melatonin levels—Melatonin plays a role in sleep and mood regulation. The levels of melatonin in the brain may be affected by the decreased amount of daylight resulting from the change in seasons.
  • Changes in serotonin levels—Serotonin is a neurotransmitter that carries messages between nerve cells and acts as a mood regulator. Like melatonin, it also is affected by light. A deficiency of serotonin is considered to be a likely cause of SAD. Its concentration in the brain varies with the seasons, the smallest amount occurring during the winter.
  • Other chemicals under investigation include the neurotransmitters norepinephrine and dopamine, and the hormone melatonin. The female sex hormones estrogen and progesterone also may be involved since women are more vulnerable to SAD than men, especially in the years between puberty and menopause.

Who is at risk for getting SAD?

A risk factor is something that increases your chance of developing a certain condition. SAD occurs most often in adolescents and women, but it is not limited to those groups. Up to 25% of the population may suffer from a mild version of SAD, and perhaps 5% experience the full disorder. While the causes of seasonal affective disorder are not entirely clear, the National Institute of Mental Health (NIMH) believes that the following factors may increase a person’s risk of developing it:

  • Being female. SAD is diagnosed four times more often in women than men.
  • Living far from the equator. SAD is more frequent in people who live far north or south of the equator. For example, 1 percent of those who live in Florida and 9 percent of those who live in New England or Alaska suffer from SAD.
  • Family history. People with a family history of other types of depression are more likely to develop SAD than people who do not have a family history of depression.
  • Having depression or bipolar disorder. The symptoms of depression may worsen with the seasons if you have one of these conditions (but SAD is diagnosed only if seasonal depressions are the most common).
  • Younger Age. Younger adults have a higher risk of SAD than older adults. SAD has been reported even in children and teens.

Symptoms of SAD

Symptoms appear and peak during the winter months. As spring and summer approach, symptoms disappear. SAD may cause:

  • Depressed mood and feelings of sadness.
  • Fatigue and lack of energy.
  • Irritability.
  • Oversleeping or insomnia.
  • Social withdrawal.
  • Difficulty concentrating.
  • Decreased sexual desire.
  • Overeating.
  • Weight gain.
  • Cravings for sweet or starchy foods.

How is SAD diagnosed?

The doctor will ask about your symptoms and medical history. A physical and psychological exam also will be done. A diagnosis of SAD will only be made if you have some of the symptoms above and:

  • Your symptoms have occurred annually for at least 2 years.
  • No nonseasonal major depressive episodes have occurred during the same period.
  • You have complete relief from symptoms during the summer months.

Treatment Options

Light Therapy

Light therapy provides a special type of lighting to your body. Therapy includes sitting a few feet away from an ultra-bright light for a certain amount of time each day, usually in the morning. You will be able to read or work during the therapy, as your eyes will remain open. Treatment usually lasts about 30 minutes per day and may be effective in preventing SAD if started prior to symptoms appearing.

There is some evidence that light therapy may be as effective as antidepressant therapy, but with fewer side effects. It is important to note that tanning beds are not recommended as a source of light therapy. They give off ultraviolet light, which can increase the risk of cancer, and have not been proven effective for treating SAD.


Many people find that getting outdoors for a walk or other exercise each day helps their symptoms.

Antidepressant Medications

If light therapy does not work or if your depression is severe, your doctor may prescribe a type of antidepressant called selective serotonin reuptake inhibitors (SSRIs). SSRIs increase the level of serotonin activity in the brain. For example, an extended release version of bupropion can help prevent SAD if started before depressive symptoms start.


Therapists help you learn ways of managing stress related to SAD. Cognitive behavioral therapy may be used to change your patterns of thinking. It allows you to notice how you react to symptoms, learn how to change your thinking, and react differently in the future. Psychotherapy has been shown to decrease the symptoms of SAD.

If you have mild SAD symptoms, increase your exposure to regular indoor and outdoor light. Start a walking program or a daily exercise routine. If you have symptoms that are interfering with your quality of life, talk to your doctor and/or a mental health professional to determine whether you have SAD and to discuss available treatments. Remember, there are a number of different treatment options that can be used alone or in combination that can help you feel better and keep a brighter outlook.

Do you think you may be suffering from Seasonal Affective Disorder? Schedule an appointment with Dr. Cook at Portsmouth Internal Medicine, today.

National Institute of Mental Health (NIMH):