Seasonal Affective Disorder

What is Season Affective Disorder?


Seasonal affective disorder is a form of depression also known as SAD or seasonal depression. SAD occurs during the fall and winter months when there is less sunlight. People with SAD experience mood changes and symptoms similar to depression. However, with SAD symptoms improve in the arrival of spring. 

SAD is more than just “winter blues,” and the symptoms can interfere with daily functioning. It can be treated.Woman-mourning-holiday-wreath-cemetary.jpg

SAD has been linked to a biochemical imbalance in the brain prompted by shorter daylight hours and less sunlight in winter. As seasons change, people experience a shift in their biological internal clock or circadian rhythm that can cause them to be out of step with their daily schedule. SAD is more common in people living far from the equator where there is less daylight hours in the winter. The most difficult months for people with SAD in the US seem to be January and February.

Symptoms and Diagnosis

SAD symptoms can vary from mild to severe and can include, many symptoms similar to major depression such as:
• Feeling of sadness or depressed mood
• Marked loss of interest or pleasure in activities once enjoyed
• Changes in appetite;  usually weight gain
• Change in sleep; usually sleeping too much
• Loss of energy or increased fatigue despite increased sleep hours
• Increase in restless activity (e.g., hand-wringing or pacing) or slowed movements and speech
• Feeling worthless or guilty
• Difficulty thinking, concentrating, or making decisions
• Thoughts of death or suicide or attempts at suicide.

Common symptoms of SAD include fatigue even with too much sleep, and weight gain associated with overeating and carbohydrate cravings. SAD may begin at any age, but it typically starts between 18 and 30 years of age.


Increased exposure to sunlight can improve symptoms of SAD. For example, long walks outside or arranging your home or office so that you are exposed to a window during the day can help.  Bright light makes a difference to the brain chemistry.
SAD can be effectively treated with light therapy, with antidepressant medicines, with talk therapy (particularly cognitive behavior therapy) or some combination of these. Light therapy involves sitting in front of a light therapy box that emits very bright light (and filters out harmful ultraviolet rays) for 30 minutes or more a day during the winter 

If you feel you have symptoms of SAD, seek the help of a trained medical professional. Similar to depression, it is important to make sure there is no other medical condition causing symptoms. SAD can be misdiagnosed as hypothyroidism, hypoglycemia, infectious mononucleosis, and other viral infections, so proper evaluation is key.  A mental health professional can diagnose the condition and suggest therapy options. With the right treatment, SAD can be a manageable condition.

If you feel the depression is severe or if you are experiencing suicidal thoughts, consult a doctor immediately or seek help at the closest emergency room.  National Suicide Prevention Lifeline - 800-273-TALK (8255)

More Information

More on light therapy (Mayo Clinic)


*In the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), this disorder is identified as a type of depression – Major Depressive Disorder with Se


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Seasonal Affective Disorder