If your mood and energy drop every year around this time, you are in large company, and for most people it stays a dip. What is worth doing about it depends on how much it gets in the way of your days, and on the calendar: the pattern is predictable, so the weeks before the darkest part of the year are the useful ones. This article lays out an Ontario autumn and winter stage by stage, and says what published research found about therapy for seasonal depression.
How common a seasonal pattern is in Canada
The Canadian Mental Health Association's British Columbia division writes that about 2 to 3% of Canadians experience seasonal affective disorder in their lifetime, and that another 15% have a milder form that leaves them slightly low but able to live without major disruption. That milder form is what people usually call the winter blues.
Seasonal affective disorder, often shortened to SAD, is a type of depression with a recurring seasonal pattern. The US National Institute of Mental Health (NIMH) describes symptoms that in most cases start in late fall or early winter, last about four to five months and go away in spring and summer. One of the criteria it lists is that the episodes come in the same season for at least two years in a row. Only a physician or another qualified clinician can make that diagnosis, and nothing in this article can tell you whether it applies to you.
Signs that the dip is more than a dip
The same NIMH page lists the signs of depression in general, such as a sad or empty mood most of the day, nearly every day, for at least two weeks, and loss of interest in things you usually enjoy. For the winter pattern it adds three more:
- sleeping much more than usual;
- overeating, with a craving for carbohydrates in particular;
- pulling back from people, which the page describes as feeling like hibernating.
Two weeks is a useful marker. A few flat days after a grey weekend are one thing. A fortnight in which work, study or the people around you start to get less of you is a reason to talk to someone.
Start with your family doctor. Tiredness and low mood can have medical causes, and CMHA advises seeing a doctor first so that other explanations, thyroid problems among them, can be ruled out.
The NIMH list also includes thoughts of death or suicide. In an emergency, call 9-8-8 (Suicide Crisis Helpline, 24/7), call 911 or go to the nearest emergency department.
An Ontario autumn and winter, one stage at a time
The timing below comes from two places: the NIMH description of when symptoms start and stop, and the points at which a large trial (described in the next section) checked on its participants, which were October, December, and January or February.
| When | What tends to happen | One thing to do then |
|---|---|---|
| Mid-October | For people with a seasonal pattern, the first signs may be showing | Write down what you notice, and look back: did the same thing happen last year and the year before? |
| From 1 November | Clocks in Ontario go back one hour on Sunday 1 November 2026, so it is dark an hour earlier in the evening | Put two or three things you enjoy into each week now, with a day and a time, before the urge to cancel arrives |
| December | NIMH places the usual start in late fall or early winter | If the two-week marker is met, book the family doctor. If you want therapy this winter, this is a reasonable time to begin |
| January and February | The trial took its main winter measurements in these months | Keep the plans you made in November, including the ones you do not feel like keeping. Tell one person how you are doing |
| March and April | Symptoms of the winter pattern lift in spring | Note what helped and the date things eased. That note is your starting point next October |
NIMH notes that, because the onset is so predictable, people with a history of the disorder might benefit from starting treatment before the season begins. It adds that few studies have tested whether seasonal depression can be prevented, so this is a reasonable idea that has not been proven.
What a therapy built for winter looked like in a trial
Cognitive behavioural therapy, CBT, has a version adapted for seasonal depression. NIMH describes two parts: learning to question the gloomy thoughts that come with the season, and behavioural activation, which means identifying and scheduling pleasant, engaging activities to offset the loss of interest. The November row of the table borrows from the second part.
The first winter
In a randomized trial published in the American Journal of Psychiatry in 2015, 177 adults in a current episode of seasonal depression had six weeks of either this therapy or daily light therapy with a 10,000-lux light box. Depression scores improved significantly in both groups and by a similar amount. On the interview measure, 47.6% of the therapy group and 47.2% of the light group were in remission at the end.
Two winters later
The follow-up paper from 2016 tracked the same people. In the first year after treatment the groups did not differ on any outcome. At the second winter, depression had come back for 27.3% of the therapy group and 45.6% of the light group.
Three limits belong next to those numbers. The therapy was given in groups, in two 90-minute sessions a week, so the trial does not show what weekly one-to-one sessions do. Both papers come from one research team, the one that wrote the therapy protocol. And in each group a good share of people did not reach remission, which is a reminder that no approach suits everyone.
Light boxes, vitamin D and medication are questions for a doctor
NIMH lists four kinds of treatment that can be used alone or together: light therapy, psychotherapy, antidepressant medication and vitamin D. Three of them are medical decisions. People with certain eye conditions, or on medications that increase sensitivity to sunlight, may need medical supervision for light therapy or a different treatment. Studies of vitamin D for seasonal depression have had mixed results, and supplements can interact with some medications. Whether a medication has a place is for a physician to discuss with you. On the cause, NIMH says researchers are still determining it, which is worth remembering when a product page sounds certain.
Four things to write down this week
- The month your mood or energy changed this year, and in the past two years if you can remember.
- How many hours you sleep now, compared with July.
- What you have stopped doing or started avoiding.
- Anything that made a previous winter easier.
Half a page is enough. It gives a doctor or a therapist something concrete to start from, and it shows you whether there is a pattern at all.
Talking it through at BridgeMinds
At BridgeMinds, Carolina Vintu, PhD, Registered Psychotherapist, works with adults and adolescents experiencing low mood and depression, and cognitive behavioural therapy is one of the approaches she draws on. Sessions are by video across Ontario, in English, Russian or Romanian. If you are unsure whether what you feel is seasonal or something else, the article on burnout and depression may help, and you can book a free 15-minute consultation to ask how therapy could look for you.
