People and media will tell you the holiday season is supposed to be a time for celebrating and good cheer. But it doesn’t always feel that way. The holidays can be stressful and put a strain on your physical and emotional wellbeing. For many, this is made worse by seasonal affective disorder—sometimes referred to as seasonal depression. Because it can be as distressing as other disorders, and shouldn’t be characterized as just winter blues, we put together this guide to answer some of your most important questions: what is seasonal affective disorder? Do I suffer from seasonal affective disorder? What causes seasonal affective disorder?

What is Seasonal Affective Disorder (SAD)?

SAD is a form of depression, so it doesn’t have its own standalone entry in the DSM-5. That doesn’t mean it should be taken lightly, though. According to the National Institute of Mental Health, in order to be diagnosed with SAD a person must meet the full criteria for major depression during specific seasons for at least two years. It’s caused by a chemical imbalance in the brain due to shorter days and less sunlight, which is why SAD tends to be seen more in the wintertime. This causes a person’s internal clock, or circadian rhythm, to shift out of sync.

Recognizing SAD Symptoms

Depression can manifest itself in many ways. Symptoms of major depression can include the following:

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

Because SAD symptoms can vary as the seasons change, the following symptoms can include the following for winter and summer:

Light box therapy / Image via Lou Sander (CC BY SA 4.0)

Light box therapy / Image via Lou Sander (CC BY SA 4.0)

Winter

  • Having low energy
  • Hypersomnia
  • Overeating
  • Weight gain
  • Craving for carbohydrates
  • Social Withdrawal

Summer

  • Poor appetite with associated weight loss
  • Insomnia
  • Agitation
  • Restlessness
  • Anxiety
  • Episodes of violent behavior

Treatment for SAD

There are four primary ways of treating SAD: light therapy, Vitamin D, medication, and psychotherapy. Medication dosages and psychotherapy sessions should be discussed with your primary care physician, therapist, or clinician.

Light therapy is exactly as it sounds. According to Harvard Health Publishing, light therapy “entails sitting close to a special ‘light box’ for 30 minutes a day, usually as soon after waking up as possible. These boxes provide 10,000 lux… That’s about 100 times brighter than usual indoor lighting; a bright sunny day is 50,000 lux or more. You need to have your eyes open, but don’t look at the light.”

Light therapy isn’t a one-size-fits-all treatment. The amount of light people need varies on an individual basis. Some people are more sensitive to light than others.

Vitamin D therapy works on the same principle as light therapy; people who suffer from SAD tend to have lower levels of Vitamin D, and so a method of treatment is to provide more Vitamin D. Not surprisingly either, a good source of Vitamin D is sunlight intake.

From a scientific perspective, the jury’s still out on Vitamin D therapy. Studies have shown mixed results and correlations, though there is no definitive evidence that a Vitamin D supplement can effectively treat SAD.

Facts and Stats

  • Between 50–80% of light therapy users have complete remissions of symptoms
  • Seasonal affective disorder occurs four times more often in women than in men and the age of onset is estimated to be between 18–30 years
  • Those living farthest from the equator in northern latitudes are most susceptible: In the United States, 1% of those who live in Florida and 9% who live in Alaska experience SAD.
  • SAD can co-occur with other depressive, bipolar, attention deficit, alcoholism, and eating disorders, making it difficult to diagnose.