Nov 9, 2025
This weekend brought the first snowfall of the season in Barrie Ontario, and the end of Daylight Saving Time was last weekend… It has suddenly become so dark and cold! Between now and December 21, the days will continue to get shorter before they begin to lengthen again.
While the snow signals the beginning of winter, the loss of daylight often marks the beginning of something more difficult for many people. For individuals who experience Seasonal Affective Disorder (SAD) or the milder “winter blues,” this period often marks the onset of symptoms. Many clients begin to describe a noticeable change in mood, motivation, and energy around the first significant shift in daylight. Although research shows that full SAD symptoms may take several weeks to develop, for many people the effects are felt almost immediately after the time change.
Seasonal Affective Disorder is a form of depression that follows a predictable seasonal pattern, typically appearing in late fall and resolving in spring. The primary cause involves changes in exposure to natural light. The Mayo Clinic explains that reduced sunlight disrupts the body’s circadian rhythm, the internal clock that regulates sleep, mood, and energy levels (Mayo Clinic, 2024).
This shift can alter the production of key brain chemicals: Serotonin, which supports mood stability, tends to decrease with reduced light exposure. At the same time, melatonin, the hormone that helps regulate sleep, may increase or become irregular. These combined effects can lead to fatigue, changes in appetite, disrupted sleep, and a general decline in mood.
A recent article from Healthline notes that individuals sensitive to time changes can begin to experience symptoms within a few days after the clocks shift, due to the sudden reduction in morning light exposure and disruption to their internal rhythm (Healthline, 2024).
Shorter days and decreased sunlight influence not only biological systems but also behaviour and cognition. People tend to spend less time outdoors, reduce physical activity, and have less social interaction, all of which are protective factors against depression. For those predisposed to mood disorders, these behavioural changes can amplify the biological vulnerability to low mood.
Even individuals without a formal diagnosis may experience what is often referred to as “winter blues,” a milder form of mood decline characterized by irritability, fatigue, and difficulty concentrating. Most people with mild symptoms acclimate within a week or two, but for those with full SAD, the symptoms persist and interfere with daily functioning until daylight increases.
For many people who have experienced SAD in previous years, symptoms can begin even before the darker months fully set in. This anticipatory phase often involves increased anxiety, irritability, or low mood that arises simply from knowing what is coming.
The brain and body “remember” the previous struggle. Through a process known as associative learning, the nervous system links environmental cues (such as shorter days, colder temperatures, or even the first snowfall) with previous experiences of fatigue, sadness, or isolation. As a result, the body can activate a stress response before the actual seasonal triggers peak.
This anticipatory reaction reflects how efficiently the brain adapts and predicts based on past experiences. Recognizing this pattern early allows individuals to begin preventive strategies sooner and to approach the season with greater awareness and agency than resignation.
The good news is that SAD and related mood changes can be treated and, in some cases, prevented. Evidence-based approaches include:
Individuals with a history of SAD are encouraged to begin preventive strategies before symptoms fully develop, as proactive measures are often more effective than reactive ones.
At VOX Mental Health, we recognize that the transition into winter can be a difficult time for many people. The biological and psychological changes associated with reduced light are real and can significantly impact daily life. Therapy offers an opportunity to understand these changes, build coping strategies, and maintain emotional stability through the darker months.
If you have noticed changes in your energy, motivation, or mood since the time change, consider reaching out for support. Seasonal Affective Disorder is both understandable and treatable. Early intervention and consistent care can make a significant difference in how you feel through the winter season.
