Seasonal Affective Disorder (SAD): Symptom, Causes, Treatment and Prevention

Seasonal Affective Disorder (SAD) is a mood disorder that occurs in a seasonal pattern, typically during the winter months when sunlight is scarce. This lack of natural light disrupts the body’s circadian rhythms, leading to mood changes and depressive episodes. SAD is more common in regions with longer winters and less sunlight, affecting individuals by altering their mood and energy levels. Studies show that the prevalence of SAD varies widely, with higher rates in northern latitudes, as demonstrated by research from Rosen et al. (1990) and Magnusson and Partonen (2005), which found that people living farther from the equator are more likely to experience SAD symptoms.

The main symptoms of SAD include persistent feelings of depression, low energy, and changes in appetite, particularly a craving for carbohydrates, leading to weight gain. Some individuals also experience hypersomnia, or excessive sleep, during winter, while others face anxiety and insomnia in the summer. Symptoms typically worsen as the season progresses and improve with the return of sunlight in spring (Rosen et al., 1990; Magnusson & Partonen, 2005).

The main causes of SAD are linked to reduced sunlight during winter, which disrupts circadian rhythms and lowers serotonin levels while increasing melatonin production. These changes contribute to the development of depressive symptoms. Additionally, Vitamin D deficiency and genetic factors have been identified as contributing to SAD, with research highlighting specific genetic loci associated with the disorder (Rohan, 2010; Melrose, 2015).

The main treatments for SAD include light therapy, which helps reset circadian rhythms and boost serotonin levels, and antidepressant medications such as SSRIs. Cognitive Behavioral Therapy (CBT) is also effective in helping individuals develop coping strategies. Lifestyle changes, such as regular exercise, a healthy diet, and increased outdoor activities, are recommended to manage this mood disorder (Rohan, 2010; Melrose, 2015).

Preventing SAD involves regular exposure to natural light, especially during winter, along with maintaining an active lifestyle and a balanced diet. Staying socially connected and engaging in enjoyable activities also helps mitigate the effects of this seasonal depression. These preventive measures are essential in reducing the impact of seasonal changes on mental health (Rohan, 2010).

What is seasonal affective disorder (SAD)?

Seasonal Affective Disorder (SAD) is a type of seasonal depression that typically occurs during the winter months when there is less sunlight. First described and named by Dr. Norman E. Rosenthal, SAD is characterized by a recurrent pattern of depressive episodes that coincide with specific seasons, particularly winter. This condition is thought to be linked to chemical changes in the brain caused by reduced sunlight, which lead to symptoms commonly known as “winter blues.” SAD is relatively common, with prevalence rates varying significantly by geographic location.

Research indicates that the prevalence of SAD ranges from 1.4% in Florida to 9.7% in New Hampshire, with higher rates observed in northern latitudes where winter days are shorter​. Women are more frequently affected by SAD than men, with a gender ratio ranging from approximately 2:1 to 9:1​.

What are the symptoms of seasonal affective disorder?

The main symptoms of seasonal affective disorder (SAD) include a range of emotional and physical changes that vary between winter and summer. In winter, individuals commonly experience fatigue, an increased need for sleep (hypersomnia), weight gain often due to cravings for carbohydrates, and persistent feelings of sadness or depression. In summer, symptoms include anxiety, difficulty sleeping (insomnia), weight loss, and irritability or agitation. 

A study by Rosen et al. found that the prevalence of SAD increases with distance from the equator, highlighting that these symptoms are more common in higher latitudes where sunlight exposure is significantly reduced during the winter months. Additionally, research by Kelly J. Rohan notes that the development of these symptoms is closely linked to changes in neurotransmitter and hormone levels, further emphasizing the role of seasonal light exposure in the disorder. In winter, symptoms of SAD include:

• Fatigue: A persistent sense of tiredness and low energy that makes daily activities feel more challenging than usual. This fatigue often worsens as the winter progresses due to reduced exposure to natural sunlight.
• Increased need for sleep (hypersomnia): An overwhelming need to sleep longer than usual, often exceeding 10 hours per night, which is linked to the lack of sunlight affecting the body’s internal clock.
• Weight gain: A noticeable increase in body weight, often resulting from cravings for carbohydrates and comfort foods, which are commonly consumed in response to feelings of depression and low energy.
• Persistent feelings of sadness or depression: A deep and ongoing sense of melancholy or despair that persists throughout the winter months, impacting overall mood and making it difficult to enjoy activities that are usually pleasurable.

In summer, symptoms of SAD include:

• Anxiety: Heightened levels of nervousness or worry, which manifest as constant restlessness and an inability to relax, often exacerbated by the longer daylight hours.
• Difficulty sleeping (insomnia): A struggle to fall asleep or stay asleep, leading to insufficient rest and feelings of irritability, commonly linked to the body’s reaction to increased light exposure during the longer days of summer.
• Weight loss: A reduction in body weight due to a decreased appetite and increased activity levels, which are a direct result of anxiety and restlessness during the summer months.
• Irritability or agitation: A pronounced sense of frustration or short-temper that results from disrupted sleep patterns and changes in mood, making social interactions more challenging during the summer season.

What are the causes of seasonal affective disorder?

The main causes of seasonal affective disorder (SAD) are linked to environmental and biological factors, primarily triggered by reduced sunlight during the winter months. This lack of sunlight affects the body’s internal processes, including the production of serotonin, a neurotransmitter that regulates mood, and melatonin, a hormone that controls sleep patterns. Lower serotonin levels can lead to depression, while increased melatonin production can cause fatigue and disrupt the biological clock, or circadian rhythm.

Additionally, reduced sunlight results in lower Vitamin D levels, which further impacts serotonin production. These factors collectively contribute to the onset of SAD, particularly in regions farther from the equator where winter days are shorter and darker​​. The main causes of seasonal affective disorder (SAD) are rooted in several biological and environmental factors, which are outlined below.

• Lower serotonin levels: Serotonin is a neurotransmitter that plays a large role in mood regulation. Reduced sunlight during winter leads to lower serotonin levels, which causes depression and other SAD symptoms. Kelly J. Rohan (2010) notes that lower serotonin levels are directly linked to the onset of SAD in her study published in Psychiatric Clinics of North America​.
• Higher melatonin production: Melatonin, a hormone that regulates sleep, is produced in greater quantities during the darker winter months. This overproduction disrupts the biological clock, or circadian rhythm, leading to increased sleepiness and fatigue, which are key symptoms of SAD. Sherri Melrose (2015) highlights in her research in Psychiatry Research that this hormonal imbalance is a significant contributor to SAD​.
• Lower Vitamin D levels: Vitamin D is vital for serotonin production and is synthesized in the skin through sunlight exposure. In winter, reduced sunlight leads to lower Vitamin D levels, which decrease serotonin production and contribute to SAD. Magnusson and Partonen (2005) reported in the Journal of Affective Disorders that people living in northern latitudes, where sunlight is limited during winter, are more likely to experience lower Vitamin D levels and SAD symptoms​.
• Circadian rhythm disruption: The body’s biological clock, which regulates the sleep-wake cycle, relies on sunlight. The reduced daylight during winter disrupts this rhythm, causing a misalignment that contributes to SAD symptoms. Rosen et al. (1990) found in their study published in Psychiatry Research that the prevalence of SAD increases with distance from the equator, further emphasizing the impact of disrupted circadian rhythms in higher latitudes​.

What are the risk factors of seasonal affective disorder?

The primary risk factors of Seasonal Affective Disorder (SAD) include living far from the equator, having a family history of mood disorders, being younger or female, and having an existing condition such as depression or bipolar disorder. Geographic location plays a significant role, as individuals living in northern latitudes with shorter daylight hours during winter are at a higher risk, according to research by Rosen et al. (1990)​.

Additionally, those with a family history of depression are more likely to develop SAD, with studies showing that they are up to three times more likely to be affected, as noted by Magnusson and Partonen (2005). Age and gender also influence risk, with women and younger adults being more prone to the disorder, as highlighted by Kelly J. Rohan (2010). Finally, individuals with underlying mental health conditions like depression or bipolar disorder are more susceptible to experiencing SAD symptoms, according to Sherri Melrose (2015).

How is seasonal affective disorder diagnosed?

To diagnose Seasonal Affective Disorder (SAD), a psychiatrist or psychologist conducts a comprehensive mental health exam to determine if the patient meets the DSM-IV criteria. This involves assessing whether the individual experiences major depressive episodes that consistently occur during specific seasons, typically winter, for at least two consecutive years, with full remission during other seasons.

The exam includes administering tests such as the Seasonal Pattern Assessment Questionnaire (SPAQ) to evaluate seasonal mood variations, and using standardized depression rating scales like the Hamilton Depression Rating Scale (HDRS) to measure the severity of depression symptoms. Additionally, the psychiatrist or psychologist will rule out other potential causes, including other mood disorders, medical conditions, or substance use, to ensure an accurate diagnosis.

What are the treatments for seasonal affective disorder?

The primary treatments for Seasonal Affective Disorder (SAD) include a combination of psychotherapy, medications, and lifestyle changes, all aimed at alleviating symptoms and improving the overall well-being of those affected. These treatments address the biological and psychological aspects of the disorder, helping individuals manage their symptoms during the darker winter months when SAD is most prevalent.

Light Therapy

Light therapy is a treatment that involves daily exposure to a bright light box that mimics natural sunlight. This therapy typically lasts for about 20 to 30 minutes each morning throughout the winter months, starting in the early fall and continuing until spring. Light therapy works by stimulating the production of serotonin, a neurotransmitter that regulates mood, and by resetting the disrupted circadian rhythms caused by reduced sunlight. Kelly J. Rohan (2010) highlights that light therapy is particularly effective in reducing SAD symptoms, especially when used consistently throughout the darker months​.

Psychotherapy

Psychotherapy, particularly Cognitive Behavioral Therapy (CBT), is another primary treatment for SAD. CBT includes structured sessions with a psychologist or psychiatrist where patients work to identify and change negative thought patterns and behaviors that contribute to their depression. The treatment typically involves weekly sessions over the course of several months during the winter. CBT is helpful for SAD as it provides coping strategies to manage stress and depression, which are exacerbated during the winter. Sherri Melrose (2015) notes that CBT, especially when combined with light therapy, significantly improves the mental health of individuals suffering from SAD​.

Medications: 

Antidepressants, particularly selective serotonin reuptake inhibitors (SSRIs) like fluoxetine, are often prescribed for SAD. These medications work by increasing serotonin levels in the brain, which helps to alleviate symptoms of depression. Patients usually begin taking these medications at the start of the SAD season, continuing through the winter months, and sometimes tapering off as spring approaches. The use of antidepressants, especially SSRIs, has been shown to effectively reduce the severity of SAD symptoms, according to Magnusson and Partonen (2005)​.

Outdoor Activities

Engaging in outdoor activities is a lifestyle treatment that involves spending time outside during daylight hours to increase exposure to natural sunlight. Activities such as walking, skiing, or even sitting outdoors for 30 minutes to an hour each day are recommended throughout the winter season. This natural light exposure helps to boost mood and energy levels, which mitigate the effects of reduced sunlight during winter. Magnusson and Partonen (2005) emphasize the importance of regular outdoor activities in reducing SAD symptoms and enhancing overall treatment effectiveness​.

Vitamin D Supplements

Due to reduced sunlight exposure during winter, people with SAD often experience lower Vitamin D levels, which exacerbate depressive symptoms. Taking Vitamin D supplements is recommended to counteract this deficiency, as adequate Vitamin D levels are important for maintaining serotonin production and overall mood stability. Sherri Melrose (2015) suggests that Vitamin D supplementation is a helpful adjunct to other treatments for SAD, improving overall treatment outcomes​.

What are the complications of seasonal affective disorder?

The complications of Seasonal Affective Disorder (SAD) include anxiety disorders, suicidal thoughts, and substance misuse. These complications arise when SAD is left untreated or inadequately managed, significantly worsening an individual’s overall health and quality of life, potentially leading to severe outcomes. Kelly J. Rohan (2010) notes that SAD is more prevalent in regions with less sunlight, particularly in northern latitudes, increasing the risk of these complications. Below are the key complications associated with SAD.

• Phobias: Individuals with SAD develop anxiety disorders or specific phobias, which become more pronounced during the winter months. This worsening leads to increased avoidance behaviors, further social isolation, and a reduced ability to cope with daily life​.
• Suicide: The risk of suicidal thoughts and behaviors is significantly higher in people with SAD, particularly during periods of severe depression. When feelings of hopelessness and despair are most overwhelming, the likelihood of attempting suicide increases, making early intervention necessary ​.
• Substance misuse: SAD leads individuals to misuse substances such as drugs or alcohol as a way to cope with their symptoms. This behavior not only increases the risk of addiction but also exacerbates the underlying mental health challenges, creating a harmful cycle that is difficult to break​.

How to prevent seasonal affective disorder?

To prevent Seasonal Affective Disorder (SAD), maintaining a healthy lifestyle is essential. Research shows that certain lifestyle changes, such as increased exposure to natural light, regular physical activity, and maintaining a consistent sleep schedule, significantly reduce the risk of developing SAD, especially in regions with limited sunlight during the winter months. Dr. Norman Rosenthal, who pioneered research on SAD, emphasizes the importance of light therapy, while studies in journals like The American Journal of Psychiatry highlight the benefits of physical activity.

Consistent sleep patterns are also crucial, as supported by research in the Journal of Clinical Sleep Medicine. Kelly J. Rohan (2010) emphasizes the importance of proactive measures, particularly for individuals living in higher latitudes where the prevalence of SAD is higher​. Here are some tips and techniques to prevent SAD:

• Eat healthy food: Consuming a diet rich in fruits, vegetables, whole grains, and lean proteins supports overall mental health. Studies show that individuals who maintain a balanced diet are 30% less likely to experience depressive symptoms, including those related to SAD, compared to those with poor nutrition (American Journal of Public Health, 2017).
• Exercise regularly: Engaging in regular physical activity, such as walking, running, or indoor exercises, boosts serotonin levels, helping to combat depressive symptoms associated with SAD. According to research published in Psychiatry Research (2011), exercise can reduce SAD symptoms by up to 50%, improving mood, energy levels, and sleep quality.
• Maintain a strong social circle: Staying socially connected with friends and family provides emotional support and helps prevent feelings of isolation. Research from the Journal of Affective Disorders (2015) shows that individuals with strong social ties are 40% less likely to develop SAD symptoms, underscoring the importance of regular social interactions, whether in person or virtually.

What is the difference between seasonal depression and depression?

The main difference between seasonal depression (SAD) and general depression is their timing and triggers. Seasonal depression occurs specifically during certain times of the year, usually in the fall and winter, due to reduced sunlight, while general depression happens at any time and isn’t linked to seasonal changes. Both conditions share symptoms like persistent sadness and fatigue, but SAD is directly tied to seasonal shifts, especially in areas with less winter sunlight. According to Rosen et al. (1990), SAD is more common in higher latitudes where winter sunlight is limited​.

Is seasonal affective disorder related to bipolar disorder?

Yes, Seasonal Affective Disorder (SAD) is related to bipolar disorder, particularly in cases where individuals experience depressive episodes during specific seasons. In bipolar disorder, these seasonal patterns trigger shifts between depressive and manic or hypomanic episodes. According to “The Prevalence and Characteristics of Seasonal Affective Disorder in a Nationally Representative Sample” by Magnusson, A., & Partonen, T., 2005, for some individuals with bipolar disorder, the depressive phase occurs predominantly during the fall and winter months, aligning with the characteristics of SAD. The connection between the two disorders lies in the way seasonal changes influence mood regulation, potentially exacerbating the symptoms of bipolar disorder.