“Winter is Coming”: Understanding Seasonal Affective Disorder

It usually starts just after Labor Day. You feel your mood start to shift down, and it becomes harder to get motivated to accomplish all the things you want to do. The light changes, and it gets dark earlier, but you seem to have trouble falling asleep at night. When you do fall asleep, it doesn’t seem as restful as even a few weeks ago. You feel sluggish during the day. Socializing feels like more of a chore than something to look forward to. You find yourself taking naps and eating sugary foods to try to make yourself feel better, but that doesn’t seem to help very much either. Could you have seasonal affective disorder (SAD), which is also sometimes called seasonal depression?

What is Seasonal Affective Disorder?

Seasonal affective disorder (SAD) is a type of depression in which symptoms occur only at some times of the year and disappear at other times. SAD typically occurs during fall or winter. September and October are often the time of year when people in the United States notice the start of symptoms. A small number of people experience SAD during spring and summer instead (called “summer-pattern SAD”). 

A seasonal pattern of depression is more common than many people realize. In the United States, about 0.5% to 3% of people in the general population report SAD symptoms. Among people with a diagnosis of major depressive disorder, about 10% to 20% have depression episodes in a seasonal pattern. This percentage rises to 25% of people with bipolar disorder.1 

What are the Symptoms of SAD?

The symptoms of SAD include some or all of the following.1 Not every person with SAD will experience every symptom. 

  • Depressed mood most of the day
  • Loss of interest or pleasure in all, or almost all, activities most of the day
  • Significant weight loss when not dieting, or weight gain without intending to gain weight, or noticeable decrease or increase in appetite 
  • Sleeping much more than usual, or having difficulty sleeping/insomnia
  • Changes in level of physical movement (being more sluggish or hyperactive than typical) that other people notice
  • Fatigue or loss of energy most of the day
  • Feelings of worthlessness or excessive guilt most of the day
  • Diminished ability to think and concentrate, or great difficulty making decisions
  • Recurrent thoughts of death or suicide 

Someone who has five or more of these nearly every day for at least two weeks in a row meets the criteria for an episode of depression. If a person experiences these episodes only in certain times of the year, then they meet the criteria for SAD. 

There are some symptoms that seem to crop up in people with SAD in particular patterns.2 

For winter-pattern SAD, specific symptoms may include:

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

Specific symptoms for summer-pattern SAD may include:

  • Trouble sleeping (insomnia)
  • Poor appetite, leading to weight loss
  • Restlessness and agitation
  • Anxiety
  • Episodes of angry or even violent behavior

What Causes SAD?

Researchers are still working on this question, but the most recent studies strongly support the idea that SAD is caused in large part by circadian rhythm disruption.3 Circadian rhythms are physical, mental, and behavioral effects that follow a 24-hour cycle. The most obvious circadian rhythm for humans is sleeping at night and being awake during the day. There are many others, including hormone levels, hunger patterns, elimination patterns, body temperature changes, and changes in mental function and alertness. These processes respond to light and dark and affect most living things, including animals, plants, and even bacteria!4

In SAD, the brain seems to have difficulty resetting circadian rhythms in response to the changing light/dark patterns in fall and winter. People with winter-pattern SAD often report that they are not sleepy at their normal bedtime and they are in bed, awake, for a long time each night. When they do fall asleep, they tend to oversleep and have difficulty getting up the next day. They may then try to take naps during the day, go to bed extra early, or sleep in on weekends, all of which can actually make the situation worse. There is definitely a genetic component to SAD, because it tends to run in families.3 

How Can SAD Be Treated?

SAD is usually treated with a combination of approaches. Some of these approaches can be guided by your primary care doctor, and can include vitamin D supplements, light-box therapy (using a light box to expose your face to bright light at certain times of the day to help reset your circadian rhythms), increasing exercise at certain times of the day, and sometimes antidepressant medication. However, one of the more effective ways to treat SAD is through psychotherapy.2

At the Rollins Counseling Center, our clinicians are trained to diagnose SAD and provide evidence-based psychotherapy to address symptoms of depression that will help you get you back to where you want to be. Please reach out today and take the first step toward feeling happier, more energized, and more motivated again!

References and Further Reading

  1. National Library of Medicine Medline Plus (2019). Seasonal Affective Disorder
  2. National Institute of Mental Health (2022). Seasonal Affective Disorder.
  3. Lewy, A. J., Emens, J. S., Songer, J. B., et al. (2009). Winter Depression: Integrating mood, circadian rhythms, and the sleep/wake and light/dark cycles into a bio-psycho-social-environmental model. Sleep Medicine Clinics, 4(2), 285–299. 

National Institute of General Medical Sciences (2022). Circadian Rhythms.