Facebook Pixel

Shedding Light on Seasonal Affective Disorder (SAD)

Published on Feb 16, 2018

Do you ever occasionally get the winter blues? Let’s face it, ‌darker days and colder months‌ ‌can leave anyone feeling less than energetic. People tend to have more enthusiasm for life when the sun is shining and the weather is fair. However, for some, the shorter and colder days may bring more than just the occasional blues.

Some people may suffer from a more severe period of sadness that can interfere with daily life. This type of seasonal depression, especially when it recurs year after year, should not be dismissed as merely a normal response to the gloom of winter.

SAD is actually a form of depression that is related to a change in seasons. Typically SAD starts in the fall and continues into the winter months, resulting in reduced energy and mood swings. As the weather warms up and the days get longer, moods generally improve. However, SAD may also occur during the warmer months.

What are some causes and risk factors for SAD?

While specific causes of SAD remain unknown, research indicates that SAD may be related to various factors such as:

  • A shift in a person’s internal (biological) clock that disrupts his or her normal sleep/wake cycle (also called circadian rhythm).
  • Trouble regulating a chemical (called serotonin) that affects mood.
  • Decreased levels of vitamin D, which may be associated with symptoms of depression. Vitamin D also plays a role in the activity of serotonin.
  • Increased levels of a hormone that regulates sleep (called melatonin).

There are several risk factors that can increase a person’s risk for developing SAD. These include:

  • Being female (women are diagnosed with SAD 4 times more often than men).
  • Living a greater distance from the equator (farther to the north or the south).
  • Having a family history of SAD.
  • Having depression or bipolar disorder.
  • Being younger (adults between the ages of 18 and 30 are at greater risk than older adults).

How is SAD diagnosed?

Diagnosing SAD can be challenging because it may include the same symptoms as major depression. To be diagnosed with SAD, symptoms must coincide with specific seasons (appearing in the winter or summer months) for at least 2 years.

The severity of symptoms of SAD may vary from mild to severe. Some symptoms of SAD may include:

  • Feeling sad or depressed.
  • Losing interest in doing things that were once enjoyed.
  • Changes in appetite such as eating more.
  • Changes in sleep habits such as sleeping more than usual.
  • Having less energy or feeling more tired than usual.
  • Showing signs of restlessness (such or hand-wringing) or having slowed speech and movements.
  • Feeling worthless or guilty.
  • Having trouble concentrating.
  • Thinking about death or suicide.

If you feel like harming yourself or others, seek professional help immediately. Call the National Suicide Prevention Lifeline at 1-800-273-8255.

How is SAD treated?

There are a number of treatments for SAD. Be sure to discuss a management plan that is best for you with your healthcare provider.

  • Your treatment should be individualized and may include a combination of medication, light therapy (sitting next to a special fluorescent light box for several minutes each day), counseling, and lifestyle modifications such as increased exposure to sunlight—outdoors, in your home, and in your office. Talk with your healthcare provider about an increased risk of skin cancer from too much sunlight.
  • Living a healthy lifestyle—including eating healthy foods, getting enough sleep, and connecting with family and friends.
  • Making outdoor exercise part of your daily life. Walk your dog in the park or stroll around the block on your lunch hour. If you prefer to exercise indoors, position yourself near a window for maximum sunlight exposure.

Elena Beyzarov, PharmD, is a pharmacist and Senior Manager, Medical Writing at Pfizer.

[1] [2] [3] [4] [5] [6]


  • 1. Mayo Clinic: Seasonal Affective Disorder (SAD). Accessed December 11, 2017.
  • 2. National Institute of Mental Health. Seasonal Affective Disorder. Accessed December 11, 2017.
  • 3. Melrose S. Seasonal affective disorder: an overview of assessment and treatment approaches. Depress Res Treat. 2015;1-6.
  • 4. Sleep.org. Circadian Rhythm and Your Body Clock. Accessed December 12, 2017.
  • 5. American Psychiatric Association. Seasonal Affective Disorder (SAD). Accessed December 11, 2017.
  • 6. Helpguide.org. Seasonal Affective Disorder (SAD). Accessed January 5, 2018.
External Resources

Quick Poll

After reading this article, how likely are you to speak with your healthcare provider (or someone you know) about seasonal affective disorder?


Subscribe To Our Newsletter!

Sign up to receive monthly newsletters and other Get Healthy Stay Healthy updates.