by Vanessa Ip

Graphic design by Raymond Zhang

With the transition to daylight savings at the end of every year, our sunlight exposure becomes limited. The decrease in sunlight, and thus vitamin D exposure, is linked to a decrease in mood. We often hear the terms “depression”, and “seasonal affective disorder” used colloquially, but what do they really entail? Seasonal affective disorder (SAD) is a clinical subtype of mood disorders with recurrent episodes of major depression occurring in a seasonal pattern,^1-3 associated with recurrent depressive episodes in the fall and winter.² Symptoms may include low mood, fatigue, changes in appetite, and loss of interest or pleasure in activities.² Although light therapy has gained interest as a novel treatment for SAD, it is not the only option. With approximately 2-3% of Canadians experiencing SAD in their lifetime, and 15% experiencing mild SAD with symptoms of slight depression, it’s timely to bring additional regimens and strategies for equality in treatment availability to light; pun intended.³

SAD has been suggested to have further implications on racialized individuals. Previous research suggests that individuals with darker skin tones are more susceptible to vitamin D deficiencies.⁴ Furthermore, African Americans have been shown to be more likely to be deficient in vitamin D, as skin pigmentation reduces vitamin D production, and subsequently developing SAD.^4,5 Interestingly, even individuals with darker eye colour have been linked to increased risk for depression and fatigue compared to those with blue eyes.⁶ However, a common limitation in research investigating SAD is the absence of racialized population samples.^7,8 Given that people of colour are at greater risk of SAD, it is important to identify the effectiveness and development of treatments.

Despite these research gaps, various evidence-based treatments for SAD have been identified for the general population and have become more popular and accessible in recent years.⁹ Similar to treatments for other mood disorders, pharmacotherapy involving second-generation antidepressants (i.e., selective serotonin reuptake inhibitors and serotonin-norepinephrine reuptake inhibitors) reduces depression scores and remission rates better than placebo.¹⁰Another option is light room therapy (LRT), which is typically done in hospitals where light boxes, meant to mimic natural sunlight with 10,000 lux of white, fluorescent light, are for patients’ personal use.^10,11 Although light boxes are easily accessible, there are better results with the use of LRT as opposed to light boxes in patient homes—namely due to exposure and intensity of light. In addition, light therapy requires patients to wake up and spend 30 minutes in the light, requiring behavioural commitment. But between light therapy and pharmacotherapy, which one is better?  Surprisingly, some evidence suggests that light therapy may have comparative benefits to pharmaceuticals!¹ One double-blind randomized controlled trial found that light therapy was equally as effective as the antidepressant fluoxetine at treating SAD.¹ Therefore, the choice between the two options will often depend on personal preference and whether patients would rather adjust their morning routines or commit to taking medication. 

Another treatment option involves cognitive behavioural therapy (CBT), a psychological intervention targeting maladaptive thinking and behavioural patterns which is well established in mood disorder treatment.¹² Several variations of CBT exist, tailored to the unique needs of different mood disorders, with CBT-SAD leveraging psychoeducation, behavioral activation, and cognitive restructuring to specifically target winter depression.¹³  CBT-SAD has shown to be comparable to light therapy treatment after one year. Whereas light therapy is more accessible and less of a time commitment, CBT had more long-term effects, despite stopping the treatment.¹³ 

However, does ethnicity influence the course of SAD presentation and treatment? When looking at research with racialized samples, light treatment has been shown to be equally as effective for treating SAD amongst African-American compared to Caucasian patients.⁵ In addition, a study looking at hospital admissions for seasonal depression found that those of Asian race had more depressive episodes in the winter. This may be due to the lower latitudes of where Asians originate, causing them to have more frequent depressive symptoms in response to the harsh weather found in higher latitudes.¹⁴ 

Beyond evidence for differing susceptibility and treatment outcomes for SAD in racialized individuals, existing systemic differences in treatment availability for mental health pose a considerable barrier for people of colour.¹⁵ This, coupled with the limited availability and insurance coverage of light boxes, make newer treatment options even less accessible.¹⁶ This disparity is further reflected in CBT-SAD treatment. Recent research supports ‘culturally adapted’ CBT as better suited for racialized individuals,¹⁷ but the more niche implementation of CBT-SAD risks generalization. Ultimately, novel SAD treatments can only be effective for racialized individuals if existing inequalities in mental health services are addressed concurrently. 

The array of treatments for SAD is encouraging, opening more options for patients to explore and tailor their treatment. The current evidence suggests that light therapy and cognitive-behavioural therapy may be most effective for treating winter depression. Given recent evidence, SAD should be treated more seriously among North American people of colour, and that treatment should be consistent and repeated over time, especially in the winter months. However, further research is necessary to better identify the genetic underpinnings and clinical outcomes of SAD, in concert with addressing systemic limitations to treatment availability. It is through more extensive research that treatments can be tailored to meet the unique needs of each individual, ensuring that no one is left behind when dealing with the cold, dark winter months. 

References

Huey SJ, Park AL, Galan CA, et al. Culturally Responsive Cognitive Behavioral Therapy for Ethnically Diverse Populations. Annual Review of Clinical Psychology. 2023;19:51-78. 

Lam RW, Levitt AJ, Levitan RD, et al. The Can-SAD Study: A Randomized Controlled Trial of the Effectiveness of Light Therapy and Fluoxetine in Patients With Winter Seasonal Affective Disorder. The American journal of psychiatry. 2006;163(5):805–12.

Seasonal affective disorder (SAD) [Internet]. 2024 [cited 2025 Jul 25]. Available from: https://www.psychiatry.org/patients-families/seasonal-affective-disorder

Seasonal affective disorder [Internet]. 2013 [cited 2025 Jul 25]. Available from: https://bc.cmha.ca/documents/seasonal-affective-disorder-2/

Stewart AE, Roecklein KA, Tanner S, et al. Possible contributions of skin pigmentation and vitamin D in a polyfactorial model of seasonal affective disorder. Medical hypotheses. 2014;83(5):517–25.

Uzoma HN. Light treatment for seasonal Winter depression in African-American vs Caucasian outpatients. World journal of psychiatry. 2015;5(1):138–46.

Goel N, Terman M, Terman JS. Depressive symptomatology differentiates subgroups of patients with seasonal affective disorder. Depression and anxiety. 2002;15(1):34–41.

Øverland S, Woicik W, Sikora L, et al. Seasonality and symptoms of depression: A systematic review of the literature. Epidemiology and Psychiatric Sciences. 2020;29:e31. doi:10.1017/S2045796019000209

Magnusson A, Partonen T. The Diagnosis, Symptomatology, and Epidemiology of Seasonal Affective Disorder. CNS spectrums. 2005;10(8):625–34.

Westrin Å, Lam RW. Seasonal Affective Disorder: A Clinical Update. Annals of clinical psychiatry. 2007;19(4):239–46.

Kurlansik SL, Ibay AD. Seasonal Affective Disorder. American family physician. 2012;86(11):1037–41.

Terman M, Terman JS. Controlled Trial of Naturalistic Dawn Simulation and Negative Air Ionization for Seasonal Affective Disorder. The American journal of psychiatry. 2006;163(12):2126–33.

What is Cognitive Behavioral Therapy? [Internet]. American Psychological Association; 2017 [cited 2025 Jul 25]. Available from: https://www.apa.org/ptsd-guideline/patients-and-families/cognitive-behavioral

Rohan KJ, Meyerhoff J, Ho SY, et al. Outcomes One and Two Winters Following Cognitive-Behavioral Therapy or Light Therapy for Seasonal Affective Disorder. The American Journal of Psychiatry. 2016;173(3):244–51.

Suhail K, Cochrane R. Seasonal variations in hospital admissions for affective disorders by gender and ethnicity. Social Psychiatry and Psychiatric Epidemiology. 1998;33(5):211–7.

Kaur N, Esie P, Finsaas MC, et al. Trends in Racial-Ethnic Disparities in Adult Mental Health Treatment Use From 2005 to 2019. Psychiatry Services. 2023;74(5):455-462. 

Oldham MA, Ciraulo DA. Use of bright light therapy among psychiatrists in massachusetts: an e-mail survey. The Primary Care Companion for CNS Disorders. 2014;16(3):PCC.14m01637