January 16, 2024

Seasonal affective disorder, also referred to as SAD, is a type of depression that is triggered by a change in seasons. It’s normal and common to feel a little down during colder months. However, SAD is more than just feeling down. It’s a form of depression that affects your daily life. Keep reading to find out more about what seasonal affective disorder is, what causes it, and its most common symptoms.

What Is Seasonal Affective Disorder?

Seasonal affective disorder is classified as a major depressive disorder with seasonal patterns. SAD most commonly starts when fall begins and then gets worse in late fall and early winter. For most people, this seasonal depression ends as spring brings sunnier days. A mild version of seasonal affective disorder is known as the “winter blues” and causes less severe symptoms. While most people get SAD in fall and winter, it is possible to experience seasonal affective disorder in summer. This is called “summer depression” and starts in late spring or early summer, then typically ends in fall. Approximately 5 percent of adults in the United States experience seasonal affective disorder, and females are more likely to be affected than males. An estimated 10 to 20 percent of Americans experience the milder “winter blues.”

Common Symptoms of Seasonal Affective Disorder

fatigued older woman laying on bed

Seasonal affective disorder causes symptoms similar to those of normal depression; however, these symptoms occur repetitively around a certain time of year. If you have seasonal affective disorder in winter, you may experience mood changes and the following symptoms of depression:

  • Sadness, feeling depressed almost every day
  • Anxiety
  • Lack of energy, extreme fatigue
  • Cravings for carbohydrates
  • Weight gain
  • Trouble concentrating
  • Feeling hopeless or worthless
  • Feeling agitated or irritated
  • Limbs feeling heavy
  • Oversleeping
  • Loss of interest in activities you usually enjoy
  • Thoughts of death or suicide

Summer depression can have different symptoms than winter SAD and may include:

  • Anxiety
  • Restlessness
  • Feeling agitated
  • Decreased appetite
  • Weight loss
  • Trouble sleeping (insomnia)
  • Violent episodes

What Causes SAD?

The exact cause of seasonal affective disorder is unknown. However, lack of sunlight seems to trigger this form of depression for those who are prone to it. There are a number of theories that suggest possible causes of SAD.

One suggestion is that when there is less sunlight, your biological clock shifts, meaning your body’s daily schedule is changed. Seasonal affective disorder may result from an inability to adjust to these changes. A chemical imbalance in the brain is another possible cause. People who are at risk for SAD may already have less serotonin, which is the chemical that contributes to feelings of happiness. Because sunlight helps your body regulate serotonin levels, a lack of sunlight in winter can lead to even lower levels, causing depression.

Along the same line of thought is the theory that a vitamin D deficiency caused by less sunlight in winter can affect your serotonin levels and mood. The lack of sunlight may also stimulate an overproduction of melatonin, which is the chemical that affects sleep patterns and mood. This can cause mood changes and feelings of sluggishness in winter.

Treatment of Seasonal Affective Disorder

young woman with SAD using light therapy as treatment

It can sometimes take a while to diagnose seasonal affective disorder because it can look like other health conditions, such as hypothyroidism, chronic fatigue syndrome, viral illnesses, low blood sugar, and various mood disorders. Once a physician diagnoses you with seasonal affective disorder, they may recommend one or more treatments. Traditional antidepressants can be prescribed to treat SAD. Your physician may also recommend that you go outside to get more natural light each morning. Light therapy, or phototherapy, is another treatment that may help if natural sunlight isn’t available. A well-balanced diet and physical activity are often recommended as well to help improve energy levels and regulate mood.

More Tips on Handling Depression

Are you struggling with seasonal affective disorder or another form of depression? It can be difficult to overcome those negative feelings and thoughts. Thankfully, there are some things you can do to help yourself get through it. Take a look at these tips on how to handle depression that can help you make it through each day.