What’s Seasonal Affective Disorder?

What’s Seasonal Affective Disorder?

You have probably heard the term “winter blues,” often used to describe the low spirits that can come with the shorter, colder days of late fall and winter. But for some people, the “blues” are much more than a temporary case of the grumps. They may have a form of depression known as seasonal affective disorder (SAD).

Statistics show that SAD affects up to 3 percent of the American population, approximately 25 percent of people with bipolar disorder, and up to 20 percent of people with major depression.

What is SAD?

SAD is a type of depression that comes and goes in a seasonal pattern. It usually begins in the fall as the days grow shorter and continues into winter. In the spring and summer, SAD symptoms either improve or go away completely. For some people, however, SAD occurs in the summer instead of – or in addition to – the winter. This is known as “summer depression.”

What are the Symptoms of SAD?

The most common sign of seasonal affective disorder is depression symptoms that start in late fall or early winter and subside during the spring and summer months. These depressive symptoms may include:

  • Feeling hopeless, worthless, or irritable
  • Having low energy levels and trouble sleeping
  • Losing interest in activities
  • Experiencing changes in your appetite or weight
  • Having difficulty concentrating
  • Feeling sluggish or agitated
  • Negative thought patterns
  • Substance abuse
  • Lack of motivation

What Causes SAD?

The exact cause of seasonal affective disorder is unknown. However, there are a few possible explanations.

Change in the biological clock: The change in seasons leads to reduced sunlight in winter. This may disrupt your body’s internal clock (circadian rhythm), which regulates sleep, mood, and hormones. As a result, your body may have difficulty adjusting to these changes, leading to SAD.

Low serotonin levels: Sunlight helps the body get enough vitamin D -which is essential in serotonin production. As a result, a reduction in sunlight exposure may cause the levels of this vital neurotransmitter to drop significantly, impacting mood and emotional processing in the brain.

Increased melatonin production: Another common theory is that SAD is caused by an overproduction of the hormone melatonin during the winter months. Melatonin is responsible for promoting sleep and is produced in large amounts in the absence of sunlight. This increased production of melatonin during winter can make you feel sluggish, sleepy, and depressed. 

Who is at risk?

Anyone can develop seasonal affective disorder, although it is more common in women and young adults. Other risk factors include:

  • Living too far away from the equator (less exposure to sunlight during the winter.
  • Having a family history of SAD, major depression, or other mood disorders
  • Has a pre-existing mental illness
  • Living in regions with excessive cloud cover

The Bottom Line

Seasonal affective disorder is a form of depression that occurs during the fall and winter months when there is less sunlight. Though it is possible to experience SAD during other times of the year, it is most common during the late fall and winter months.

If you think you may be experiencing seasonal affective disorder, it is important to talk to your doctor as soon as possible; without proper treatment, SAD can get worse with time and potentially lead to major depressive disorder or anxiety.

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