Seasonal Depression: When the Darker Months Bring More Than the Winter Blues

Sep 29

It starts quietly, somewhere around the time the clocks change. You wake up in the dark and come home in the dark. Getting out of bed feels like wading through wet sand. You crave carbohydrates, sleep longer than usual, and still feel exhausted. Plans with friends start to feel like too much, so you cancel them. By December, the things that normally bring you joy seem distant, and you find yourself counting the weeks until spring.

For many Canadians, this pattern is familiar. Some people experience a mild dip in mood and energy during the darker months. For others, it becomes a true depressive episode that returns year after year. This post explores the difference between the winter blues and seasonal depression, why the change in seasons affects mood, and what helps, including why autumn is the best time to prepare.

Winter blues or seasonal depression?

Many people notice lower energy and mood when the days grow shorter. According to the Canadian Mental Health Association, about 15% of Canadians experience milder winter blues, while about 2% to 3% will experience seasonal affective disorder (SAD) in their lifetime (Mood Disorders Society of Canada, n.d.). These figures are estimates and vary by study and region.

The difference is one of degree and impact. The winter blues are uncomfortable but manageable. Seasonal depression is a form of major depression that follows a seasonal pattern, usually beginning in fall or winter and lifting in spring or summer. In diagnostic terms, clinicians describe it as major depressive disorder with a seasonal pattern (American Psychiatric Association, 2022). It can significantly affect work, relationships, and daily functioning.

Common signs of winter-pattern seasonal depression include persistent low mood, loss of interest in usual activities, oversleeping and difficulty waking, increased appetite and carbohydrate cravings, fatigue and a heavy feeling in the body, withdrawal from social contact, and difficulty concentrating. A less common summer pattern also exists, often involving insomnia, reduced appetite, and agitation.

These signs overlap with other conditions, including non-seasonal depression, bipolar disorder, thyroid problems, and other medical issues, so it is worth exploring them with a professional rather than drawing conclusions on your own.

Why the seasons affect mood

Researchers have proposed several explanations, and the full picture is still being studied.

The body clock. Light is the main signal that keeps our internal body clock, or circadian rhythm, aligned with the day. When mornings stay dark, that clock can drift out of sync with our daily schedule, affecting sleep, energy, and mood. Changes in the timing of melatonin, a hormone that helps regulate sleep, are thought to play a role.

Brain chemistry. Earlier studies suggested that the brain's serotonin system shifts with the seasons. A 2026 meta-analysis found that serotonin transporter levels stay stable across seasons in healthy people, and suggested that the larger seasonal swings seen in some studies of people with SAD may reflect a specific vulnerability rather than a normal pattern (Pak, 2026). In other words, the science is evolving, and seasonal depression is unlikely to have a single cause.

Behaviour and mood feeding each other. When it is cold and dark, many people naturally do less: fewer walks, less socializing, less time on meaningful activities. Reduced activity and connection can lower mood, and lower mood makes it harder to stay active. This cycle is one of the targets of therapy for seasonal depression.

What helps

The encouraging news is that seasonal depression responds well to treatment, and there is a Canadian evidence base to guide it.

Light therapy. The Canadian Network for Mood and Anxiety Treatments (CANMAT) recommends bright light therapy, using a 10,000-lux white light for about 30 minutes daily, as a first-line treatment for depression with a seasonal pattern (Lam et al., 2024). Light therapy is usually done in the morning, but timing and dose should be guided by a health professional. It is important to speak with your doctor before starting, particularly if you have bipolar disorder, a history of hypomania or mania, eye conditions, or take medications that increase light sensitivity. Light therapy can trigger hypomania in some people with bipolar disorder.

Cognitive behavioural therapy. A version of CBT adapted for seasonal depression, known as CBT-SAD, focuses on reshaping the thoughts and behaviours that deepen winter low mood, including planning enjoyable and meaningful winter activities. In a randomized trial of 177 adults, CBT-SAD and light therapy worked similarly well in the first winter. Two winters later, however, people who had received CBT-SAD were less likely to have a recurrence, 27.3% compared with 45.6% for light therapy (Rohan et al., 2016). The researchers noted that many people stop using light therapy in later winters, while skills learned in CBT tend to stay with them.

Medication. Antidepressant medication can also help, and a physician can discuss whether it is appropriate for you.

Everyday supports. Getting outside during daylight, keeping a consistent wake time, staying physically active, and protecting social connection can all support mood through the darker months. These are helpful additions, but they are not a substitute for treatment when symptoms are significant.

Why autumn is the time to prepare

Because seasonal depression tends to return at a similar time each year, it offers a rare advantage: you can plan ahead. If you have noticed a pattern in past years, early fall is a good time to talk with your doctor or therapist, consider whether light therapy is right for you, and build a winter plan with regular activities, social contact, and routines already in place before your mood dips.

Reflection questions worth exploring

These prompts are best explored with a professional rather than used to reach conclusions on your own.

Have I noticed my mood, energy, or sleep changing around the same time each year?
When does the change usually begin, and when does it lift?
What activities and connections tend to disappear from my life in winter?
What helped, even a little, in past winters?
What would a realistic winter plan look like for me this year?

Support at Vive Wellness Therapy

At Vive Wellness Therapy, we understand that the darker months can bring more than a passing dip in mood. We offer a space to explore seasonal patterns, build practical strategies, and create a plan to support you through fall and winter, working alongside your medical care where needed. If you would like support, we would be glad to hear from you whenever you feel ready.

References

American Psychiatric Association. (2022). Diagnostic and statistical manual of mental disorders (5th ed., text rev.). https://doi.org/10.1176/appi.books.9780890425787

Lam, R. W., Kennedy, S. H., Adams, C., et al. (2024). Canadian Network for Mood and Anxiety Treatments (CANMAT) 2023 update on clinical guidelines for management of major depressive disorder in adults. The Canadian Journal of Psychiatry, 69(9). https://doi.org/10.1177/07067437241245384

Mood Disorders Society of Canada. (n.d.). It is that time of year: Seasonal affective disorder and the winter blues. https://mdsc.ca/it-is-that-time-of-year-seasonal-affective-disorder-the-winter-blues/

Pak, K. (2026). Brain serotonin transporter remains stable across seasons: A Bayesian and frequentist meta-analysis. NeuroImage, 340, 122231. https://doi.org/10.1016/j.neuroimage.2026.122231

Rohan, K. J., Meyerhoff, J., Ho, S. Y., Evans, M., Postolache, T. T., & Vacek, P. M. (2016). Outcomes one and two winters following cognitive-behavioral therapy or light therapy for seasonal affective disorder. American Journal of Psychiatry, 173(3), 244–251. https://doi.org/10.1176/appi.ajp.2015.15060773

This article is provided by Vive Wellness Therapy for general informational and educational purposes only. It is intended to be used alongside professional therapy and medical care and is not a substitute for assessment, diagnosis, or treatment by a qualified health professional. Please speak with your doctor before starting light therapy or any new treatment. Research and clinical guidance evolve over time, and information in this article may become outdated or contain inaccuracies. If you are in crisis or thinking about suicide, call or text 9-8-8 (Suicide Crisis Helpline, available 24/7 across Canada; in Quebec, calls connect to 1-866-APPELLE). If you or someone else is in immediate danger, call 9-1-1 or go to your nearest emergency department.