Seasonal Affective Disorder (SAD): A Fitting Acronym


Many of us are trying to adjust to the recent time change (and shortening days), with chilly darkness setting in earlier and earlier. No more daylight for that after-work run!

Roughly 10-20% of people in U.S. may experience some degree of low mood and energy during the winter months, when its colder and darker, and we may feel stuck inside more. Seasonal Affective Disorder (SAD) is different from these milder “winter blues”; it is more severe and causes significant distress and impairment in functioning. And it can be associated with suicidal thoughts. It is important to know that SAD is treatable (more information below).

In a given year, 5-6% of the population experience an episode of SAD. The vast majority of these—more than 75%—are women.  

SAD is a cyclical mood disorder: people experience depression in the fall and winter months, year after year. For a given person, the depression starts and stops around the same time each year. The depressive symptoms tend to begin late fall/early winter and dissipate mid-spring, when the days get sunnier and longer (although some people may experience onset later, in the winter or early spring.)  The symptoms generally start gradually and worsen as winter progresses, often peaking in January and February in the U.S. 

In a much smaller subset of people, SAD presents with “summer depression,” with onset in the spring and improvement in the fall.

Winter SAD often presents with depressed mood, low energy (feeling “leaden”), moodiness (mood swings and irritability), and difficulty getting out of bed in the morning, along with other symptoms of depression. These include:

  • Sleep disturbance
  • Appetite changes (usually increased appetite, intense carbohydrate craving and weight gain)
  • Loss of interest or enjoyment in things
  • Trouble with concentration, focus, and decision-making
  • Feelings of worthlessness, guilt, or hopelessness
  • Social withdrawal and increased anxiety about social rejection 
  • Agitation (such as pacing, difficulty sitting still) or being slowed down
  • Thoughts of death or suicide
  • People are more likely to develop SAD if they have family members with a mood disorder (SAD, depression or bipolar disorder), live further from the equator (northern locations in the U.S.), or have major depression or bipolar disorder themselves.

The cause of SAD is not known, but there are several theories. Shorter days and less sunlight may cause chemical changes in the brain.  For example, less exposure to sunlight can cause shifts in our circadian rhythm; our “biological clock” strongly impacts our mood, sleep and hormones. Also, the release of melatonin, the “sleep hormone,” is stimulated by darkness. Melatonin plays a role in sleep and mood and helps regulate our circadian rhythm. Therefore, increases/changes in melatonin release may play a role in SAD. Also, less exposure to sunlight may lead to reduced levels of serotonin, which has been implicated in depression. Sunlight is crucial to vitamin D production, so low Vitamin D levels may also be a factor.

The diagnosis of SAD depends on identifying the seasonal pattern. To meet formal criteria, one would need to experience a major depressive episode during the same time frame for two consecutive years. And generally, the pattern is present for the majority of years (but not necessarily every year). Also, the number of seasonal depressive episodes significantly outnumbers episodes which have occurred at other times of year. Without treatment, episodes can last for 4-5 months, for as much as 40% of the year. 

SAD is more common in people with bipolar disorder, another cyclical mood disorder. It’s crucial to assess for this, as the course of illness and the treatment can be substantially different (and regular antidepressant treatment can make bipolar disorder worse).

Luckily, there are several effective treatment approaches for SAD, sometimes used in combination: 

  • Exposure to sunlight and spending time outdoors, especially in the mornings, can help boost mood.  This can also entail increasing the amount of sunlight that shines into one’s home and workspace.
  • Bright Light Therapy, or phototherapy, is the first-line treatment for SAD. It involves sitting in front of a standardized light box (10,000 lux) for 20-60 minutes each morning during the winter months (people often eat breakfast or read during this time). People can start using the light box in the fall, before the usual onset date of their winter depressive episodes. (Consult with a doctor if you have eye problems, light sensitivity, or possible bipolar disorder.) Here’s more information:
  • Psychotherapy, including Cognitive Behavioral Therapy (CBT)
  • Antidepressant medications 
  • Vitamin D supplementation (under the guidance of your healthcare provider)

In addition to formal treatment, here are some other strategies and considerations for coping with SAD:

  • Consider changing location: if you suffer from SAD and are at a time of transition in your life, such as deciding between a job offer in a northern state vs. a southern state, take this into account.  Living closer to the equator can have a profound effect on how you feel and function during the winter months. Alternatively, consider spending the winter in a warmer, sunnier climate (“snow birding”).
  • Plan ahead. Know your mood patterns.
  • Confide in supportive people. Accept help. 
  • Avoid alcohol and recreational drug use. 
  • Exercise regularly.
  • Avoid making major life decisions when depressed.
  • Plan/do enjoyable things with others.
  • Remember that this will resolve over time, as previous episodes have.
  • As the American writer and naturalist Hal Borland said, “No winter lasts forever; no spring skips its turn.”

If you, or someone you know, is having suicidal thoughts, know that you are not alone. Also know that help is available 24/7. Call your healthcare provider, go to the emergency room or call the National Suicide Prevention Lifeline, 1-800-273-TALK. 


Please enter your comment!
Please enter your name here