What is Seasonal Affective Disorder (SAD)? - Symptoms & Treatment

Instructor: Jennifer Kinder
Explore the causes, prevalence, and symptoms of seasonal affective disorder illustrated with a real-life example. Learn treatment options that are effective for alleviating this disorder, then test your knowledge with a quiz.

What is Seasonal Affective Disorder

Gina has always suffered from the 'winter blues.' Every year, for as long as she can remember, she starts to feel depressed beginning in the fall and stays that way until the beginning of spring. She feels down most of the day and feels sluggish no matter how long she sleeps. Nothing Gina does seems enjoyable, and she has gained 15 pounds due to her insatiable appetite for carbs. Gina feels like her head is in a fog and struggles to concentrate at work. When she can't focus and be productive, she feels worthless.

In general, Gina can't wait for summer to get here so that she feels normal again. She's tired of feeling so terrible every winter and decides it's time to talk to her doctor, who then refers her to a psychologist. The phsychologist diagnoses her with seasonal affective disorder, or SAD. Her doctor and psychologist work together to prescribe medication, talk about issues that might lead to her depression, and teach her about light therapy. Gina feels hopeful that her days of the 'winter blues' are gone once she starts to feel the depression lift.

Seasonal affective disorder is a specific type of depression that causes depressive symptoms during certain seasons. More often than not, the symptoms occur in the fall and winter months, and they disappear in the spring and summer. As much as 20% of the people in the U.S. will experience SAD over their lifetime. SAD is believed to be caused by a chemical imbalance affecting the circadian rhythm, which is responsible for regulating our sleep/wake cycle. When this system is out of whack, it can have profound effects on mood and sleep.


The main symptoms of SAD are those of a major depressive episode, which is the clinical term to diagnose depression. To be diagnosed with SAD, one must experience at least five of the following symptoms, almost every day, for at least two weeks:

  • Feeling depressed
  • Not enjoying activities
  • Significant, unintentional weight gain or loss
  • Sleeping too much or too little
  • Feeling sluggish or sped up
  • Being tired or having no energy
  • Feeling worthless or having undeserved guilt
  • Unable to concentrate or make decisions
  • Often thinking about death or suicide

When someone experiences the above symptoms during the same seasons of the year reliably for two years, has a remission of symptoms the rest of the year, and has experienced this pattern more years than not, they could be diagnosed with SAD.

Although the following symptoms are not part of the diagnostic criteria for SAD, if people are experiencing SAD during the winter months, they commonly might also experience:

  • Irritability
  • Interpersonal problems
  • Feeling overly sensitive to rejection
  • Heavy feeling in the arms and legs
  • Craving carbohydrates

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