Motivation and emotion/Book/2024/Seasonal affective disorder

Seasonal affective disorder:
What is SAD, what are its causes, and how can it be treated?

Multimedia presentation (3 min)

Overview

Figure 1. An image of a woman with head in hands named Stacey Scenario Stacey is a 20-year-old university student. Since she started high school, she has noticed a pattern of her mood and behaviour that she can’t seem to shake. When winter starts, she finds it hard to get out of bed and find motivation to do anything, she secludes and isolates herself because she can’t find the energy to socialise with her peers or family. She has also noticed that her grades and school attendance tend to be worse in the colder months. She has been talking to her psychologist who thinks she may have major depressive disorder with a seasonal pattern, or seasonal affective disorder (SAD).

Figure 2. An image of a rainy day

Seasonal affective disorder (SAD) is a mood disorder characterised by symptoms that follow a cycle with the season changes. Symptoms appear at a specific time each year with full remission at other times in the year (Chen et al., 2024; Melrose, 2015). The fifth and most current edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) categorises it as a subtype or qualifier of major depressive disorder or bipolar I or II disorder (American Psychiatric Association, 2013). SAD effects an estimated 5-10% of the general population (Fonte & Coutinho, 2021; Nevarez-Flores et al., 2023). The most common form of SAD is the autumn/winter subtype, where symptoms begin to manifest with onset of colder weather in autumn and persist throughout winter. These symptoms slowly reduce in intensity as the weather warms in spring, reaching full remission by summer (APA, 2013). This pattern is why it is often referred to as "winter blues" or "winter depression" (Nevarez-Florez, 2020; Melrose, 2015).

Increased frequency of rain and/or snow weather events as pictured in Figure 2 as well as lower temperatures and higher wind speeds are contributing factors to Autumn/Winter SAD (Brazienė, 2022). It is less common but still possible to experience this in reverse, around 10% of those experiencing SAD experience the onset of symptoms in Spring/Summer and remission in Autumn/Winter (Melrose, 2015).

Key points: SAD differs from depression and bipolar disorder. It relates to the seasons, symptoms of SAD come and go with the time of year (American Psychiatric Association, 2013; Chen et al., 2024; Melrose, 2015) SAD is a common disorder, effecting 5-10% of the global population (Nevarez-Flores et al., 2023). Autumn/Winter SAD is the most common subtype, only 10% of people with SAD experience the Spring/Summer subtype (Melrose, 2015)

Focus questions: What is SAD? What causes SAD? How can SAD be treated?

What are the signs and symptoms of SAD?

SAD is recognized in the DSM-5 as a specifier for depression and bipolar I and II disorders, with symptoms that align with depressive, manic, or hypomanic episodes (APA, 2013). The key distinction between SAD and non-seasonal forms of these mood disorders is the consistent timing of episodes, which occur at the same time each year, followed by either full remission or a shift in the symptoms at another time of year. To be diagnosed with SAD or a mood disorder with a seasonal pattern, the symptoms must occur recurrently over at least two consecutive years and significantly impact daily functioning and quality of life (APA, 2013).

In addition to the core symptoms of depressive, manic, or hypomanic episodes, individuals with SAD commonly experience:

• hypersomnia (excessive sleep)
• increased appetite
• cravings for carbohydrates
• profound fatigue (Chen et al., 2024)
• physical pain
• weight loss or gain
• sleeping pattern disruptions
• lack of energy
• inability to concentrate
• feelings of worthlessness or excessive guilt
• recurrent thoughts of death or suicide (APA, 2013; Kazdin, 2000)

Key points: Symptoms of SAD manifest as recurrent episodes that occur at the same time each year, with either full remission or a shift in symptoms at a different time of year (APA, 2013) As a subtype of major depressive disorder, symptoms typically include depressive, manic, or hypomanic episodes (like major depressive disorder) (APA, 2013) Individuals with SAD most commonly experience hypersomnia, increased appetite, carbohydrate cravings, and profound fatigue (Chen, 2024)

What are causes of SAD?

Psychological and physiological theories aim to identify the underlying causes of SAD in order to mitigate its effects. These theories have informed various treatment methods designed to alleviate SAD symptoms. The most widely accepted explanation is that the changes in available sunlight during different times of the year are the primary cause of SAD.

Hormonal changes

Research has provided empirical evidence to support the theory that SAD is caused by changes in hormones and chemicals in the body and brain. The main hormones attributed to the onset of SAD are serotonin and melatonin (Garbazza & Bandetti, 2018). Research has also found a correlation between SAD and vitamin D deficiency (Melrose, 2015). Research has identified external factors that can influence the production and distribution of these hormones and therefore cause episodes of SAD.

Daylight and circadian rhythms

It is theorised that the amount of available sunlight in a season affects the brain's ability to produce and regulate neurotransmitters and hormones. Specifically, SAD is related to transmission of serotonin and overproduction of melatonin (Melrose, 2015). There is growing evidence to support the theory that seasonal changes to the light-dark cycle affect the biological clock or circadian rhythm of individuals and worsen symptoms of mood disorders, however, these factors can also be manipulated to treat manic and depressive episodes using methods like bright light therapy (Garbazza & Bendetti, 2018). Research has also found a correlation between SAD and vitamin D deficiency, which is said to explain why SAD is more common closer to the poles where the seasonal change in the light-dark cycle is the most extreme. Those who live 33 degrees north or 30 degrees south of the equator are unable to synthesise Vitamin D from the sun between November and February (Melrose, 2015).

Behavioural changes and routine interruptions

Some evidence suggests that the changes in routine and daily experiences and comfort levels change with the seasons. With this is mind for Autumn/Winter SAD, weather events like snow and rain can happen more frequently, which can make commuting and spending time outdoors less comfortable. In more extreme cases, weather like this can also effect transport and other aspects of day-to-day life. Lower temperatures also call for more or warmer clothes, and extra financial expenses (e.g., heating a home) can increase stress and initiate SAD symptoms. Similarly in Spring/Summer SAD, weather events like droughts and bushfires, cause extra stress. This being said, the DSM-5 specifies that a person cannot be diagnosed with SAD if their seasonal depressive symptoms are better explained by seasonally related psychosocial stressors like lack of unstable employment at certain times of the year (APA, 2013).

Risk factors

There are certain characteristics and attributes that increase the likelihood of developing SAD.

Geographical location

Research indicates that risk of SAD is higher for more northern latitudes as it is observed more frequently in the northernmost countries and becomes more sporadic closer to the equator and in southern latitudes (Garbazza & Bandetti, 2018; Melrose, 2015; Nevarez-Flores et al., 2023).

Family history

As with most depressive disorders, research has provided evidence of an inherited component (Garbazza & Bendetti, 2018). Family history of depression or SAD is a risk factor of SAD, accounting for up to 29% of the variance of seasonal symptoms of depression in both men and women (Madden et al., 1996).

Gender

SAD is more common amongst females than it is males (APA, 2013; Garbazza & Bandetti, 2018; Oginska & Oginska-Bruchal, 2014).

Age

SAD is most commonly developed in younger people, aged 18-30 years (Rohan et al., 2015).

Key points: The leading theories posit that SAD is caused by changes in hormones caused by seasonal changes, light the light-dark cycle (Garbazza & Bendetti, 2018; Melrose, 2015). another possible explanation for SAD is that changes in season bring on changes in behaviour and routine which can make people uncomfortable or stressed. However when considering the diagnostic criteria in the DSM5 there is a note that specifies that the symptoms experienced can't be due to "seasonally related psychosocial stressors" which puts this theory into question. Risk factors for SAD include: geographical location, family history, gender and age.

Treatments for SAD

There are several effective treatment options available for Seasonal Affective Disorder (SAD). The choice of treatment often depends on the specific symptoms an individual exhibits and the type of SAD they experience, whether it be Autumn/Winter or Spring/Summer SAD. Here are the most common and effective treatments:

Phototherapy/bright light therapy

Bright light therapy (BLT) is an effective treatment of SAD, particularly for the autumn/winter subtype. The treatment has been used for over 30 years (Pjrek et al., 2020). It involves exposing individuals with SAD to a bright light, usually in the morning, to stimulate natural sunlight and regulate circadian rhythms. Generally, BLT involves daily exposure to 10,000 lux for 20-60 minutes first thing in the morning, and has been found to have less severe adverse effects than other treatment methods like antidepressants (Melrose, 2015). By compensating for the reduced daylight during the colder months, this therapy is effective at alleviating SAD symptoms such as fatigue and low mood (Galima, Vogel & Kowalski, 2020; Rohan et al., 2015).

Cognitive behavioural therapy

Cognitive behavioural therapy (CBT) is a form of psychological treatment that is based on the principles that psychological disorders and problems are rooted in learned behaviour and maladaptive thought patterns. CBT posits symptoms can be relieved by relearning helpful and healthy ways of thinking and behaving. The approach is applied liberally across most psychological disorders, and has been found to be especially effective at negating symptoms of depression and anxiety (Gaudiano, 2008). Research has found CBT to be effective in treating SAD (Rohan et al., 2015), one study in which participants with SAD attended two weekly 90 minutes group sessions of CBT for 6 weeks proved to be just as effective as 30 minutes of daily BLT (Melrose, 2015).

Medication / antidepressants

Antidepressant medications are commonly used in the treatment of depression and bipolar disorders, including SAD. Selective serotonin reuptake inhibitors (SSRIs) are often prescribed to help regulate moods and manage depressive episodes. Medications are frequently used in conjunction with other treatments like BLT or CBT to enhance their effectiveness. Research has found SSRIs to be as effective and well tolerated as light therapy, as well as more cost effective in some cases. Taking SSRIs early in the season (before SAD symptoms start to manifest) can prevent recurrence of seasonal depressive episodes (Melrose, 2015). For individuals with more severe or persistent symptoms, medication can play a crucial role in stabilizing mood and reducing the intensity of depressive episodes (Rohan et al., 2015).

Key points: BLT is used to treat autumn/winter SAD by increasing the amount of light that a person is exposed to during seasons where there is available sunlight (Galima, Vogel & Kowalski, 2020; Pjrek et al., 2020; Rohan et al., 2015). CBT is utilised to help individuals with SAD to relearn patterns of thoughts and behaviours to support a more helpful and healthy outlook and reduce the effects of their SAD symptoms (Gaudino, 2008; Melrose, 2015; Rohan et al., 2015). Psychiatric medications like SSRIs are also often utilised in combination with other forms of therapy to support them by changing chemicals in the brain to either make them more susceptible to treatment or reduce the effects of depression, mania or hypomania (Melrose, 2015; Rohan et al., 2015).

1 What does SAD stand for?

	Super Addictive Drugs
	Seasonal Affective Disorder
	Season Alert Disorder
	Season Aversive Depression

2 Where does research suggest that SAD is most common?

	northern latitudes
	southern latitudes
	on the equator

Conclusion

SAD, also known as "winter blues" and "winter depression" is a mood disorder considered by the American Psychiatric Association as a subtype or specifier of major depressive and bipolar I and II disorder (APA, 2013). It's defining feature is the strong temporal relationship between the onset of symptoms and seasons (Chen et al., 2024; Melrose, 2015). Symptoms manifest at the same time each year, and reach full remission at another time each year, this pattern repeats annually and must be observed for a minimum of two years to be diagnosed (APA, 2013). Symptoms of SAD are that of major depressive disorder, bipolar I and II; individuals experience depressive, manic and/or hypomanic episodes, as well as sleep disruption, appetite changes, weight changes, physical pain, recurrent thoughts of suicide and/or excessive guilt, as well as a variety of other symptoms (APA, 2013; Chen et al, 2024). The leading theories on SAD posit that it is caused by changes in hormone production that result from seasonal changes like light-dark cycles, this may explain why SAD is more common further away from the equator where seasonal changes in light-dark cycles are the most extreme (Garbazza & Bendetti, 2018; Melrose, 2015). Other than geographical location, risk factors that increase the likelihood of SAD include: family history, gender and age (APA, 2013; Garbazza & Bandetti, 2018; Madden et al., 1996; Melrose, 2015; Nevarez-Florez et al., 2023; Oginska & Oginska-Bruchal, 2014; Rohan et al., 2015). The main methods of the treatment for SAD are BLT, CBT and antidepressant medications like SSRIs. The most common treatment is BLT, which simulates sunlight exposure and aims to regulate circadian rhythms, it has proved to be effective and has less adverse effects than medication (Galima, Vogel & Kowalski, 2020; Melrose, 2015; Pjrek et al., 2020; Rohan et al., 2015). CBT is a method of talk therapy that research has found can be just as effective as BLT when utilised consistently (Melrose, 2015). Antidepressant medications have been found to be effective on most forms of depression and depressive symptoms, and have even been successfully used as form preventative symptom management in SAD (Melrose, 2015).

Key takeaways SAD is a subtype or specifier of major depressive disorder and bipolar I and II disorder. As such the symptoms experienced in SAD are the same as in depression and/or bipolar I and II. SAD is treatable, symptoms are managed with BLT, CBT and SSRIs.

See also

• Light therapy (Wikipedia)
• Vitamin D and emotion regulation (Wikiversity)

References

American Psychiatric Association. (2023). Specifiers for bipolar and related disorders. In Diagnostic and statistical manual of mental disorders (5th ed.). https://doi.org/10.1176/appi.books.9780890425596

American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). American Psychiatric Association.

Brazienė, A., Venclovienė, J., Vaičiulis, V., Lukšienė, D., Tamošiūnas, A., Milvidaitė, I., Radišauskas, R. & Bobak, M. (2022). Relationship between depressive symptoms and weather conditions. Environmental Research and Public Health, 19(9). https://doi.org/10.3390/ijerph19095069

Chen, Z. W., Zhang, X. F. & Tu, Z. M. (2024). Treatment measures for seasonal affective disorder: A network meta-analysis. Journal for Affective Disorders, 350(1) 531–536. https://doi.org/10.1016/j.jad.2024.01.028

Fonte, A. & Coutinho, B. (2021). Seasonal sensitivity and psychiatric morbidity: Study about seasonal affective disorder. BMC Psychiatry, 21. https://doi.org/10.1186/s12888-021-03313-z

Galima, S. V., Vogel, S. R. & Kowalski, A. W. (2020). Seasonal affective disorder: Common questions and answers. American Family Physician, 102(11) 668–672.

Garbazza, C. & Benedetti, F. (2018). Genetic factors affecting seasonality, mood, and the circadian clock. Frontiers in Endocrinology, 9. https://doi.org/10.3389/fendo.2018.00481

Gaudiano, B. (2008). Cognitive-behavioural therapies: Achievements and challenges. BMJ Mental Health, 11(1) 5–7. https://doi.org/10.1136/ebmh.11.1.5

Kazdin. A. E. (2000). Encyclopedia of Psychology. American Psychological Association.

Madden, P. A., Heath, A. C., RosenThal, N. E. & Martin, N. G. (1996). Seasonal changes in mood and behaviour. The role of genetic factors. JAMA Psychiatry, 53(1) 47–55. https://doi.org/10.1001/archpsyc.1996.01830010049008

Melrose, S. (2015). Seasonal affective disorder: An overview of assessment and treatment approaches. Depression Research and Treatment, https://doi.org/10.1155/2015/178564

Nevarez-Flores A. G., Bostock, E. C. S. & Neil, A. (2023). The underexplored presence of seasonal affective disorder in the southern hemisphere: A narrative review of the Australian literature, Journal of Psychiatric Research, 162(1) 170–179. https://doi.org/10.1016/j.jpsychires.2023.05.003

Oginska, H. & Oginska-Bruchal, K. (2014). Chronotype and personality factors of predisposition to seasonal affective disorder. Chronobiology International. 31(4) 523–531. https://doi.org/10.3109/07420528.2013.874355

Pjrek, E., Friedrich, M. E., Cambioli, L., Dold, M., Jäger, F., Komorowski, A., Lanzenberger, R., Kasper, S. & Winkler, D. (2020). The efficacy of light therapy in the treatment of seasonal affective disorder: A meta-analysis of randomized controlled trials. Psychiatry and Psychology, 89(1) 17–24. https://doi.org/10.1159/000502891

Rohan, K. J., Mahon, J. N., Evans, M., Ho, S. Meyerhoff, J., Postolache, T. T. & Vacek, P. M. (2015). Randomized trial of cognitive-behavioural therapy versus light therapy for seasonal affective disorder: Acute outcomes. American Journal of Psychiatry, 172(9) 817–924. https://doi.org/10.1176/appi.ajp.2015.14101293 open_in_new

External links

• International directory of mental health helplines (Helpguide.org)
• DSM5 (American Psychiatric Association)