Seasonal Affective Disorder

Feeling the blues this time of year? You’re not alone, as many people go through short periods of time when they feel sad or not like their usual selves. Sometimes, these mood changes begin and end when the seasons change. People may start to feel “down” when the days get shorter in the fall and winter (also called “winter blues”) and begin to feel better in the spring, with longer daylight hours. In some cases, these mood changes are more serious and can affect how a person feels, thinks, and handles daily activities. Seasonal Affective Disorder (SAD) affects 0.5 to 3 percent of individuals in the general population. Knowing the symptoms, who are more at risk, and treatment is important to know so you can advocate not only for yourself but your loved ones as well. 

In most cases, SAD symptoms start in the late fall or early winter and go away during the spring and summer. SAD is not considered a separate disorder but is actually a type of depression characterized by its recurrent seasonal pattern, with symptoms lasting about 4 to 5 months per year. 


Symptoms of major depression may include:

  • Feeling depressed most of the day, nearly every day
  • Losing interest in activities you once enjoyed
  • Experiencing changes in appetite or weight
  • Having problems with sleep
  • Feeling sluggish or agitated
  • Having low energy
  • Feeling hopeless or worthless
  • Having difficulty concentrating
  • Having frequent thoughts of death or suicide

For winter-pattern SAD, additional specific symptoms may include:

  • Oversleeping (hypersomnia)
  • Overeating, particularly with a craving for carbohydrates
  • Weight gain
  • Social withdrawal (feeling like “hibernating”)


To be diagnosed with SAD, a person must meet the following criteria:

  • They must have symptoms of major depression or the more specific symptoms listed above.
  • The depressive episodes must occur during specific seasons (i.e., only during the winter months or the summer months) for at least 2 consecutive years. However, not all people with SAD experience symptoms every year.
  • The episodes must be much more frequently than other depressive episodes that the person may have had at other times of the year during their lifetime.

To help diagnose SAD, a thorough evaluation generally includes:

  • Physical exam. Your healthcare provider may do a physical exam and ask in-depth questions about your health. In some cases, depression may be linked to an underlying physical health problem.
  • Lab tests. For example, your healthcare provider may do a blood test called a complete blood count (CBC) or test your thyroid to make sure it’s functioning properly.
  • Psychological evaluation. To check for signs of depression, your health care provider or mental health professional asks about your symptoms, thoughts, feelings, and behavior patterns. You may fill out a questionnaire to help answer these questions.

At Risk

Those living in Alaska or New England may be more likely to develop SAD than people living in Florida. Furthermore, SAD is also more common in people with major depressive disorder or bipolar disorder, especially bipolar II disorder, which is associated with recurrent depressive and hypomanic episodes (10 to 20 percent of people with major depressive disorder and about 25 percent of people with bipolar disorder get SAD). Seasonal Affective Disorder sometimes runs in families and other findings suggest that people with SAD produce too much melatonin.

Research also suggests that sunlight controls the levels of molecules that help maintain normal serotonin levels, but in people with SAD, this regulation does not function properly, resulting in decreased serotonin levels in the winter. Likewise, deficits in vitamin D may exacerbate these problems because vitamin D is believed to promote serotonin activity.


Treatments are available that can help many people with SAD. They fall into four main categories that may be used alone or in combination:

Everyone has tough days and times when life causes an increase in overall stress. It’s ok to have a bad day. However, SAD is a type of depression, and if your symptoms do not improve, or even worsen, it may be time to seek professional support. Treatment options can include psychotherapy, medications, and even light box therapy. Luckily, recovery from any diagnosable mental illness has high success rates, with 70-90% recovery rates when we seek treatment.