Seasonal affective disorder (SAD) is a type of depression that recurs with a seasonal pattern. Many people feel down and less energetic when the shorter, colder days of winter arrive. This is sometimes referred to as “seasonality.” However, SAD is much more than feeling down.

SAD is a debilitating form of major depressive disorder (MDD) that disrupts an individual’s ability to function. SAD is also associated with physical and mental health risks, including substance use disorders and suicidality.

According to the Standard Diagnostic Manual for Mental Health Disorders (the DSM-5), seasonal affective disorder is not a separate disorder of its own. It occurs when individuals meet the criteria for MDD and their symptoms arise during a specific season every year with full remission in between. To be considered SAD, the depression must occur for at least two consecutive years.

Seasonal affective disorder is treatable, and subsequent episodes of seasonal depression can be prevented. Of course, affected individuals must first recognize that they are suffering from SAD and seek the appropriate help. To know when to seek help, it’s important to have an understanding of seasonal affective disorder.

Some people may not recognize that they suffer from this depressive illness because of common seasonal affective disorder myths and misunderstandings. Understanding this condition requires differentiating between the myths and facts about seasonal affective disorder.

1. Myth: Seasonal affective disorder only occurs during winter.

Fact: Although rare, SAD may occur in spring or summer.

Seasonal affective disorder seems to be caused primarily by the reduced duration of light exposure, so people who have shift-work jobs in the summertime may be susceptible to SAD during that season. Mountainous or rainy areas can block the sunlight, and inhabitants in these areas are more likely to develop seasonal affective disorder in summer. Otherwise, summer-onset seasonal affective disorder is relatively rare.

The physical causes of seasonal affective disorder are related to the duration of daily sun exposure and not the season. Because the days are shorter in the winter, people are far more likely to develop SAD during that season. That is also why the incidence of seasonal affective disorder increases in more northern latitudes, where the days become progressively shorter in wintertime.

Interestingly, people with winter SAD typically crave carbohydrates and gain weight while they are depressed. Those with the summer variant, however, are known to have a reduced appetite and tend to lose weight. Other differences in symptomatology include:

  • Summer variant SAD is associated with aggressive behavior and anxiety while winter variant SAD is not
  • Winter SAD is associated with hypersomnia (increased sleep) and withdrawal from life while summer variant SAD is associated with insomnia

2. Myth: Lightbox treatment is always effective for SAD.

Fact: Bright light therapy is an effective treatment for some people with SAD, but it does not work for everyone. 

Bright light therapy (BLT) is a well-established therapy for seasonal affective disorder. With light therapy, the depressed individual sits in front of a special lightbox for 20 to 60 minutes every day, usually first thing in the morning. The light must be a specially designed lightbox for seasonal affective disorder. Tanning beds, UV lamps or even full-spectrum lights won’t work.

These SAD lightboxes give off 10,000 lux of light intensity (by contrast, indoor lighting is about 500 lux, and a bright sunny day is about 50,000 lux). The individual must keep their eyes open without looking directly at the light, and the UV light is filtered out for safety reasons.

Light therapy has been shown to be as effective as antidepressant medications for treating SAD, but it doesn’t work for everyone. Some people cannot use a lightbox for medical reasons, such as people affected by bipolar disorder or eye problems. People should consult their physician prior to starting bright light therapy to confirm the diagnosis of SAD. They should also make sure BLT is appropriate for them and determine the intensity and duration of exposure they should use.

Other options for treating SAD can be used with or without BLT. These include:

3. Myth: SAD only impacts people living in overcast climates.

Fact: Seasonal affective disorder is related to the daily duration of light exposure, not the brightness of the light.

The prevalence of SAD depends largely on where people live, and it tends to be more prevalent at higher latitudes. For example, the risk of developing SAD at some point in a person’s lifetime is 9.7% in New Hampshire but only 1.4% in Florida. Although Florida generally has a warmer and sunnier climate than northern states, seasonal affective disorder in warm climates can still occur.

Seasonal affective disorder appears to be related to the duration of daily light exposure, not the intensity of the light. Northern areas have fewer daylight hours in winter, which is the reason behind the higher incidence of seasonal affective disorder in higher latitudes. It has nothing to do with the amount of cloud cover.

It is true that the body has an “internal clock.” The brain’s internal clock keeps time for the whole body. It is largely driven by light exposure, as the hypothalamus of the brain is light-sensitive and uses daylight to guide the body’s daily rhythm. With the change in the duration of daylight with each season, the body’s internal clock becomes desynchronized. This has major effects on metabolism and physical and mental health.

The hormone melatonin also appears to be heavily involved in the onset of SAD. The hypothalamus in the brain releases melatonin in response to darkness. Melatonin makes us feel sleepy, and it is also associated with low mood. That is why people feel tired earlier in the evening when it is winter. The duration of melatonin release is increased during the longer dark hours in winter, which makes people feel tired and down.

The combination of the disrupted circadian clock and the increased production of melatonin can bring about symptoms of depression. To top it off, the brain chemical serotonin is produced in lower amounts during dark hours. Therefore, it is produced at its lowest levels during the long winter nights. Deficiency of serotonin is a major cause of depression.

4. Myth: Seasonal affective disorder only affects women.

Fact: SAD affects mostly women, but men are not immune.

Gender-based seasonal affective disorder statistics show that there are significant gender differences in SAD. Women are affected in a ratio of 4:1 compared to men. This means that 20% of those who develop SAD are men.

Researchers are not certain about why women are more susceptible to SAD. It has been proposed that women are more susceptible to mood changes related to dark and cloudy weather, and they are also more susceptible to the depressing effects of shorter, colder days. The idea is that women are therefore more susceptible to the increased melatonin production and reduced serotonin levels that come with the shorter days.

Overall, women have twice the risk of developing any kind of major depression than men, largely due to hormonal factors. It has been suggested that the disruption in the circadian rhythm that accompanies winter has a disruptive effect on the female hormonal cycles. This may contribute to their higher risk of SAD.

5. Myth: SAD is a minor form of depression.

Fact: SAD is a type of major depressive disorder.

By definition, seasonal affective disorder meets all the criteria for a major depressive disorder. As such, major depression and seasonal affective disorder share the same debilitating symptoms and risk for co-occurring mental and physical health problems, substance abuse and suicidality.

Seasonal affective disorder is much more severe than simply feeling down and less energetic with the shorter days and cold weather. Because it is a type of depression, seasonal affective disorder and depression share the same core symptoms:

  • Depressed mood
  • Loss of interest in activities, including enjoyable ones
  • Withdrawal from normal life activities
  • Low libido
  • Low energy, fatigue, lethargy
  • Appetite changes (increased or decreased)
  • Sleep changes (increased or decreased)
  • Poor concentration
  • Feelings of guilt, worthlessness, hopelessness and stress
  • Agitation
  • Suicidal thoughts or actions

As well, to meet the diagnostic criteria for SAD, the symptoms must cause significant functional disability. If left untreated, severe seasonal affective disorder can cause a long-lasting recurrent source of disability and greatly limit a person’s ability to fulfill their life potential.

6. Myth: People with SAD can just snap out of it.

Fact: SAD is not caused by a negative attitude; it is caused by specific abnormal physical changes in the brain and body.

This myth is a dangerous one because it may prevent people from seeking seasonal affective disorder treatment. Instead of finding treatment, they may suffer the symptoms and experience life-altering consequences. Depression is the leading cause of disability worldwide. It is also known to cause or worsen physical, mental and substance use disorders.

People who have not suffered from depression may have difficulty in understanding the experience. When they see a loved one with SAD, they may think that it is just a matter of “cheering up” or “snapping out of it.” They may even discourage seeking professional help. However, SAD is a serious mental health disorder and not something that people can just think their way out of.

People with SAD should seek and accept help. The illness can persist for months if left untreated, resulting in unnecessary suffering and disability. As well, the condition is likely to recur annually unless treated.

The Recovery Village offers a comprehensive professional assessment and treatment programs co-occurring depression and substance use disorder. Contact us today to speak with one of our admissions specialists.