Understanding Seasonal Affective Disorder (SAD): Why the Seasons Affect Our Mood
As the days grow shorter and the temperatures drop, many people notice a shift in their energy, motivation, and overall mood. You might feel more tired, less social, or just “off.” While these feelings are common in winter, for some individuals they go beyond the typical winter blues — developing into Seasonal Affective Disorder (SAD), a form of depression that follows a seasonal pattern.
In this post, we’ll break down what SAD is (and what it isn’t), explore why it happens, and share evidence-based strategies to help you manage seasonal mood changes — including when to consider seeking professional support.
What Is Seasonal Affective Disorder?
Seasonal Affective Disorder (SAD) is a type of depression that typically occurs during the fall and winter months, when daylight hours are shorter. It’s characterized by many of the same symptoms as major depressive disorder, but with a recurring, seasonal pattern.
Common symptoms include:
Persistent low mood or feelings of sadness
Fatigue or low energy
Changes in sleep (often oversleeping)
Increased appetite or cravings for carbohydrates
Difficulty concentrating
Loss of interest in activities once enjoyed
Withdrawal from social interaction
Symptoms usually begin in late fall, peak during the winter, and subside in spring or early summer when sunlight increases. While most people with SAD experience the “winter pattern,” a smaller group experience the opposite — depression during summer months.
What SAD Isn’t
It’s important to distinguish SAD from the “winter blues.” Many people feel a bit slower or less motivated during colder, darker months — that’s a normal seasonal adjustment. But SAD goes deeper. It involves significant, sustained changes in mood and functioning that interfere with daily life.
SAD also isn’t a sign of weakness or lack of willpower. It’s a biological and psychological response to environmental changes, often involving shifts in brain chemistry and circadian rhythm. Recognizing this distinction can be validating — and it’s the first step toward seeking effective help.
Why Does SAD Happen?
The exact cause of Seasonal Affective Disorder isn’t fully understood, but several biological factors play a role.
1. Reduced Sunlight Exposure
Shorter daylight hours in fall and winter can disrupt your body’s internal clock, known as the circadian rhythm. This rhythm regulates sleep, mood, and energy levels over a 24-hour cycle, using light as one of its main cues. When sunlight decreases, your circadian rhythm can fall out of sync — leading to fatigue, irritability, and low mood.
2. Changes in Brain Chemistry
Sunlight influences the production of serotonin, a neurotransmitter linked to feelings of happiness and well-being. Lower light exposure can reduce serotonin levels, contributing to depressive symptoms.
At the same time, the hormone melatonin — which helps regulate sleep — tends to be produced in greater quantities in darkness. Elevated melatonin can make you feel sluggish or sleepy during the day.
3. Vitamin D Deficiency
Sunlight is a natural source of vitamin D, which plays a role in mood regulation. During winter, decreased sun exposure can lead to lower vitamin D levels, which may exacerbate symptoms of depression.
Together, these changes create a kind of “perfect storm” — disrupting your body’s natural rhythm and emotional balance.
Strategies to Help Manage SAD
While Seasonal Affective Disorder can feel discouraging, several strategies can help alleviate symptoms and support your mental health through the darker months.
1. Maximize Natural Light
Try to spend time outdoors during daylight hours, even on cloudy days. A morning walk or sitting near a sunny window can help regulate your circadian rhythm and boost serotonin production. Opening curtains wide and arranging your workspace near natural light can also make a difference.
2. Light Therapy (Phototherapy)
One of the most well-studied treatments for SAD is light therapy, which involves sitting near a special light box that mimics natural sunlight. Used for about 20–30 minutes each morning, it can help reset your circadian rhythm and improve mood within a few weeks.
Note: It’s best to consult a healthcare provider before starting light therapy to ensure it’s safe and appropriate for you.
3. Maintain a Consistent Routine
Keeping a regular sleep schedule, eating balanced meals, and maintaining consistent wake-up times helps stabilize your body’s internal clock. Even small habits — like waking up at the same time every day or doing a brief morning stretch — can reinforce a healthy rhythm.
4. Exercise Regularly
Physical activity increases serotonin and endorphins, both of which lift mood and energy. Aim for at least 30 minutes of moderate exercise most days — whether it’s walking, yoga, or dancing in your living room.
5. Stay Connected
Winter can make it tempting to hibernate, but social interaction is crucial for mental well-being. Make plans with friends, join a group activity, or reach out to loved ones regularly. Social connection provides emotional support and can counteract isolation.
6. Mindfulness and Stress Management
Practices like mindfulness meditation, journaling, or deep-breathing exercises can help reduce stress and promote a sense of calm. These activities help you become more aware of mood changes and better equipped to manage them.
When to See an Individual Therapist
If your symptoms persist for more than two weeks, significantly affect your daily life, or you find it hard to cope, it’s time to reach out for help. A mental health professional — such as a psychologist, therapist, or psychiatrist — can evaluate your symptoms and recommend evidence-based treatment options.
Treatment may include cognitive-behavioral therapy (CBT), which helps identify and change negative thought patterns, or antidepressant medication if symptoms are severe. In many cases, a combination of therapy and lifestyle adjustments provides the most relief.
At Manas Cor Psychological Services, our therapists provide individual therapy in Washington, DC, for Seasonal Affective Disorder and other mood-related challenges. Together, we’ll work to understand your unique experiences, identify patterns that contribute to seasonal mood changes, and develop personalized strategies for relief.
The Takeaway
Seasonal Affective Disorder is more than just a dislike for winter — it’s a real and treatable condition rooted in biological and environmental changes. Understanding how light, brain chemistry, and circadian rhythms influence mood can help you take proactive steps to protect your mental health throughout the year.
If you notice seasonal patterns in your mood or energy, know that you’re not alone — and help is available. With the right strategies and support, it’s possible to find balance and light, even during the darkest months.
Find Support and Light Through the Season
If the shorter days have begun to take a toll on your mood, energy, or motivation, know that you don’t have to face it alone. At Manas Cor Psychological Services, our clinicians offer individual therapy in Washington, DC, to help you navigate SAD and other mood-related challenges with care and evidence-based support.
Reach out today to schedule a consultation — and take the first step toward feeling more balanced, connected, and at ease this season.
Explore our blog posts for more insights into therapy, seasonal affective disorder, and more!
Get paired with a compassionate therapist and explore the roots of your seasonal symptoms, strengthen your coping strategies, and help you feel more grounded as you move through the winter months.
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About the Author
Dr. Datta received her doctorate from the University of Virginia and currently serves as an Assistant Clinical Professor of Psychology at The George Washington University, where she provides supervision and classroom training for doctoral students in the Clinical Psychology PhD program.
At Manas Cor Psychological Services, Dr. Datta specializes in supporting clients through complex and interpersonal trauma, severe mood disorders, grief and loss, and identity development, particularly among professionals and women of color.
Outside of her clinical work, Dr. Datta enjoys diving into a good book and exploring the world of video games.
