Understanding Seasonal Affective Disorder

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Seasonal affective disorder (SAD) is a form of depression that follows a seasonal pattern, most commonly beginning in fall and continuing through winter, then lifting in spring. It is described clinically as major depression with a seasonal pattern. SAD is linked with reduced daylight in darker months, which affects the body clock, mood-related brain chemicals, and sleep. It is especially relevant in places with long, dark, and rainy winters, such as coastal British Columbia. SAD is different from the milder "winter blues" many people feel, and it is treatable.

What Seasonal Affective Disorder Looks Like

• Low mood most of the day, most days, during the fall and winter months.
• Sleeping much more than usual and still feeling tired.
• Increased appetite, especially craving carbohydrates, and weight gain.
• Low energy and difficulty getting going in the morning.
• Loss of interest in activities and withdrawing from people.
• Difficulty concentrating.
• Feelings of hopelessness or worthlessness.

A less common pattern involves summer depression, which may include insomnia, reduced appetite, and agitation. For most people with SAD, symptoms return around the same time each year and lift as days lengthen. At work, productivity may drop in winter. At home, people may pull away from family and social plans.

Why It Happens

Reduced daylight in fall and winter can disrupt the circadian rhythm, the internal clock that regulates sleep and mood. Less light can affect serotonin, a brain chemical linked with mood, and change melatonin production, which influences sleepiness. People who live farther from the equator, have a family history of depression, or have existing mood disorders are at higher risk. SAD often begins in young adulthood and is more common in women.

In rainy climates, overcast days reduce light exposure even further. Spending most daylight hours indoors, as many people do in winter, compounds the effect. This is why light exposure is central to treatment.

Because SAD tends to follow a predictable pattern, planning ahead is one of its advantages. People who know their difficult months can arrange morning light exposure, schedule social plans and activities, protect sleep, and let others know when support might be needed, before the lowest point arrives.

What It Is Not

• Not just the winter blues. The winter blues are mild and do not significantly affect functioning. SAD is a form of clinical depression.
• Not holiday stress alone. Holiday-related sadness, explored on the page about feeling sad around the holidays, is linked with events rather than light.
• Not always seasonal. If depression persists year-round, it may be another form of depression.
• Not bipolar disorder, though some people with bipolar disorder have seasonal mood patterns. Periods of unusually high energy in spring or summer should be discussed with a doctor.

How It Is Assessed and Treated

A physician or psychologist assesses SAD by exploring the timing and pattern of symptoms over several years and ruling out other causes, such as thyroid problems. Treatments include light therapy using a light box, usually each morning, which has good evidence for winter SAD. Cognitive behavioural therapy adapted for SAD helps people challenge negative thoughts and plan activities through the darker months. Medication prescribed by a physician may also be used. Getting outside in daylight, regular exercise, and consistent sleep and wake times support mood. Starting strategies before symptoms usually begin can reduce their severity.

Getting Support at Pacific Maple Psych Centre

If fall and winter bring a predictable drop in mood and energy, therapy can help you plan for the darker months and reduce the impact of seasonal depression.