Seasonal affective disorder, commonly referred to as SAD, is often thought of as “winter depression,” a mental health condition that shows up when the days get shorter and skies are gray. But according to Devon Kienzle, DO, a family medicine provider who sees patients at both Skagit Regional Health - Darrington Family Medicine and Skagit Regional Health - Smokey Point, this assumption leaves out a bigger part of the story.

More than winter blues

As Dr. Kienzle explains in the podcast, “Seasonal Affective Disorder,” SAD has a seasonal pattern to it. While most people experience symptoms in the fall and winter, SAD can also appear in the spring and summer months. This means that many people may be struggling without realizing their symptoms follow a seasonal rhythm.

This matters because those experiencing mood changes in sunnier seasons may not recognize what’s happening or may assume they “shouldn’t” feel depressed when weather is nice. However, SAD is tied to biological and psychological patterns, not just the weather outside.

Seasonal shifts in mood

Researchers don’t know the exact cause of SAD, but several theories help explain why symptoms appear when they do:

• Circadian rhythm disruption: As daylight changes, so does the body’s internal clock. Dr. Kienzle notes that “our sleep pattern changes…and that change can lead to an onset of depressive symptoms.”
• Serotonin levels: Shifts in sunlight may affect serotonin, a neurotransmitter tied to mood regulation.
• Genetic factors: Some people may be more biologically predisposed to seasonal mood changes.
• Light exposure: Even small changes in light can influence sleep, energy and mood.

While winter SAD is more common, the spring-summer version may involve different biological triggers, including increased sunlight or temperature changes.

Recognizing the symptoms

SAD shares many symptoms with major depressive disorders, but the key difference is timing. Symptoms appear during a specific season and improve when that season ends.

Common signs include:

• Changes in sleep patterns (often sleeping more during winter SAD)
• Loss of interest in activities
• Low energy
• Difficulty concentrating
• Changes in appetite (often increased cravings for carbs)
• Feelings of guilt or worthlessness

Dr. Kienzle highlights a crucial distinction, stating “The real difference between winter blues and depression is the severity of your symptoms.” If symptoms interfere with daily life, it’s time to seek support.

When to see a doctor

If you or someone close to you notices changes in mood, energy or behavior that follow a seasonal pattern, it’s worth talking to a healthcare provider. Dr. Kienzle emphasizes if symptoms affect your daily activities or relationships, professional support can make a meaningful difference.

Listen to the “Seasonal Affective Disorder” podcast or to read the transcript.