Seasonal Affective Disorder (SAD): Symptoms, Causes, and Treatment

Those who have heard about seasonal affective disorder (SAD) may know it as seasonal depression. Although some may assume that it is a depressive disorder distinct from major depressive disorder (MDD), it is actually a specifier of MDD encompassing symptoms that set it apart from other specifiers. This mental health condition, though seemingly less debilitating due to its predictability, can pervade many aspects of the affected individual’s life.

What Is Seasonal Affective Disorder?

Seasonal affective disorder is a recurrent form of major depression that is marked by significantly low moods that coincide with changes in season. Typically, individuals with SAD experience major depressive episodes every winter or sometimes in the fall. However, some cases indicate that a depressive episode can occur every summer or spring, with seasonal affective disorder symptoms remitting during colder seasons.

Simply put, SAD is a type of major depression based on a seasonal pattern. Such depressed moods come at a particular time in the year, but when the season changes, the individual’s mood gradually returns to baseline. That is, they may no longer feel depressed—at least, for some months until the season that triggers their depression comes again.

Who Is At Risk for Seasonal Affective Disorder?

Although seasonal depression can affect anyone, there are some documented factors that put certain groups of people at risk of developing this subtype of major depression, mainly the following:

• Gender. Seasonal affective disorder largely affects women. In fact, women are four times more likely than men to develop SAD [*].
• Proximity to the equator. Individuals who live in regions found in the northern latitudes are at higher risk of developing SAD compared with individuals who do not [*]. For example, among those who live in Alaska, 9% suffer from SAD, as opposed to Florida, where 1% of its population live with SAD [*].
• Exposure to sunlight. Those who do not get enough sunlight may develop SAD eventually, especially if coupled with the two factors previously mentioned.
• Work schedule. Professionals who work on a rotating shift schedule are susceptible to having seasonal depression [*]. This is, in part, due to working at night or in the wee hours of the morning, when they are not exposed to the sun.
• Age. Children and adolescents may also be at higher risk for the winter-type seasonal pattern of major depression [*].

Given these risk factors, women who work in the healthcare profession, for example, are at a uniquely high risk of experiencing SAD.

What Are the Symptoms of Seasonal Affective Disorder?

Children and adolescents with major depression may be diagnosed with the seasonal affective disorder specifier if they meet the following criteria [*]:

• Relationship between onset of depression and time of year. There should be an established pattern of a major depressive episode occurring during a certain time in the year, usually in the fall or winter. However, if there are other circumstances in play that are clearly triggering the depressive episode, SAD can be ruled out. For instance, if the individual dreads spending time with their family during the winter holidays, then it is likely that this is the factor making them vulnerable to a major depressive episode and not the time of year per se.
• Relationship between full remission and time of year. There should also be a certain time in the year when the seasonal affective disorder symptoms abate. For example, in the spring, the individual may no longer feel depressed and may reacquire their interest in things that they normally enjoy. For those who have bipolar disorder with the seasonal pattern specifier, they may experience a manic or hypomanic episode instead of a full remission.
• History of both temporal relationships. The individual suspected of having seasonal depression should have experienced the major depressive episode and its associated periods of full remission in a consistent seasonal pattern for the past 2 years. If they suffered from a major depressive episode during other times in those 2 years, then they are not likely to suffer from SAD.
• More seasonal major depressive episodes than nonseasonal. In cases where the individual has experienced major depressive episodes during other times in the year, then the seasonal major depressive episodes should significantly outweigh the nonseasonal depressive episodes in number over their lifetime.

What Are the Causes of Seasonal Affective Disorder?

There are several theories that attempt to explain why depression in children, adolescents, and even adults is experienced only during certain times of the year. Some of the main theories are the following:

• Delayed circadian rhythm. According to the phase-shift hypothesis, individuals with SAD have an abnormally delayed circadian rhythm or internal body clock. When an individual’s body clock is out of phase in the fall or winter months, this affects the time when their melatonin (a hormone regulating our sleep-wake cycles) is released at night [*].
• Lower serotonin levels in the winter. According to research focusing on neurotransmitters, serotonin (a chemical in the brain implicated in major depression) levels are more depleted during the winter compared to summertime. It seems to be the neurotransmitter that primarily affects metabolism following a seasonal pattern [*]. It follows then that individuals with seasonal affective disorder may also have a Vitamin D deficiency since Vitamin D has been linked to serotonin activity [*].
• Genetics. Looking at it from a genetic viewpoint, research has found that seasonality is heritable. Studies have shown that there is a moderate to high genetic contribution to seasonal depression [*].

What Are Complications Associated With SAD?

As with major depression, seasonal affective disorder is a serious condition that needs to be taken seriously. Fortunately, not many people experience this condition. Up to 7.9% of the general population meet the criteria for seasonal depression in any given year, depending on the geographical region [*].

Among these individuals, they are susceptible to experiencing several complications, some of which are the following:

• Social withdrawal. Individuals with SAD may start to self-isolate, not just avoiding mingling with their acquaintances and friends but also shutting out their loved ones.
• Poor sleep quality. Because affected individuals with the winter type of SAD have significantly high levels of melatonin, they are prone to experiencing excessive sleeping. Meanwhile, those with the summer type of SAD have low melatonin levels, causing sleep disruptions [*].
• Negative thoughts and feelings. It is common for people with SAD to also suffer from negative thoughts and feelings, which result from the fact that seasonal affective disorder symptoms can be debilitating. Seasonal depression can limit the affected person from doing certain activities as well, which exacerbates the depression.

How Is Seasonal Affective Disorder Diagnosed?

As with other mental illnesses, seasonal affective disorder requires differential diagnosis, which simply means that a clinician will make a diagnosis after ruling out other disorders with similar symptoms. This is typically done by requesting the individual suspected of having the psychological disorder to undergo some tests, as well as a series of clinical interviews.

Given this, the possibility that the condition may be a physical illness should be ruled out. In addition, seasonal affective disorder symptoms should not be better explained by sleep disorder, as well as environmental factors that coincide with certain seasons (e.g., a loved one having passed away during the winter months). Essentially, it is when the clinician is able to determine that other illnesses do not explain the individual’s mood disturbance that seasonal depression is considered as the likely diagnosis.

How Is Seasonal Affective Disorder Treated?

Much research has been conducted not only in relation to the theories behind SAD but also in relation to which seasonal affective disorder treatments are most effective. Some of these treatments are light therapy, medication and vitamins, psychotherapy, and lifestyle changes.

Light Therapy

Light therapy, also known as phototherapy, is widely known as the standard treatment option for seasonal affective disorder. In this treatment modality, bright artificial light is used as a replacement for natural sunlight.

Antidepressants

Because seasonal affective disorder is associated with low levels of serotonin, antidepressants are often prescribed to affected individuals. Antidepressants are one of the common seasonal affective disorder treatments, as it targets dysfunction in serotonin activity. Specifically, second-generation antidepressants, such as selective serotonin reuptake inhibitors (SSRIs), are typically prescribed, having shown promise in terms of effectively treating SAD.

Psychotherapy

Psychotherapy can also help individuals with seasonal depression. A common counseling approach to treating SAD is cognitive-behavioral therapy (CBT). When using CBT with teenagers who have SAD, the therapist encourages them to go through a series of steps to identify and challenge their maladaptive thoughts, feelings, and behaviors. The same goes with CBT for children with seasonal affective disorder, except that the child’s parents or caregivers are more heavily involved in their treatment. To enhance the effectiveness of psychotherapy, both the clinician and the client can also use these depression worksheets so that the client’s seasonal affective disorder symptoms can be better understood and mitigated.

Sunlight Exposure

If the bright artificial lights used in light therapy don’t suffice, then perhaps getting natural sunlight will be more effective. Individuals with SAD can take short walks outdoors or have a picnic at the park so that they get as much sun as possible. Alternatively, they can open their curtains or blinds at home to expose themselves to more natural light.

Vitamin D

As said earlier, vitamin D deficiency is one of the possible causes of SAD. This explains why vitamin D may be effective for the treatment of seasonal depression. The typical recommended dose of vitamin D is 100,000 IU daily, which may alleviate seasonal affective disorder symptoms.

Lifestyle Changes

Finally, lifestyle changes, such as engaging in physical activity, can improve mood and overall well-being in clients with SAD. Studies have shown time and time again that there is a positive correlation between exercise and mental health. With that said, individuals with seasonal affective disorder can add regular exercise to their daily routine, such as walking, dancing, or swimming.

Can SAD Be Prevented?

As much as being diagnosed with seasonal depression can be disheartening, it can also be prevented. The silver lining to having the seasonal pattern of major depressive disorder is that you can predict which times in the year you are most likely to be depressed. You can thus prevent the development of SAD by getting as much sunlight as possible, taking vitamin D, and incorporating exercise into your routine.

When to See a Doctor for SAD

Now that you know the signs and risk factors of seasonal affective disorder, it is strongly recommended to see a doctor as soon as possible if you notice that you meet some of the diagnostic criteria. However, it should also be noted that seeking professional help at the earliest time possible can prove to be most beneficial. In doing so, you can counteract any of the vulnerabilities that put you at risk of developing SAD, or any other mental illness for that matter.

The Bottom Line

Although seasonal affective disorder symptoms are predictable in its course and manageable once detected, it can also still be incapacitating for the affected individual. For instance, seasonal depression may interfere with personal and professional commitments during certain times in the year. Furthermore, it can also be frustrating for these individuals, knowing that they will likely be depressed again in the upcoming months. Fortunately, there are some treatments and self-care practices (such as the use of self-care worksheets) available that can help these individuals overcome their seasonal mood disturbances.

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