Seasonal Affective Disorder (SAD): Why Winter Affects Mood and What You Can Do About It
- The Team at Upper East Side Psychology
- 32 minutes ago
- 6 min read
Introduction
Has this brief stretch of warm weather in New York City reignited your will to live? You’re not alone.
Many people notice a significant lift in mood when the sun returns after a long winter. For some individuals, this shift is more than just a preference for warmer weather—it reflects the powerful ways seasonal changes can influence mental health.
Approximately 5% of adults in United States experience Seasonal Affective Disorder (SAD), according to the American Psychological Association, and many more experience what is commonly referred to as the “winter blues.” While the winter blues may involve mild fatigue or irritability, Seasonal Affective Disorder is a clinically recognized form of depression that significantly impacts mood, energy, sleep, and motivation (Rosenthal et al., 1984).
For those who do not experience seasonal depression, it can be hard to understand why darker months affect others so strongly. For those who do, it can be easy to forget that the season itself may be contributing to changes in mood, until the sun finally begins to return.
So what exactly is Seasonal Affective Disorder? Why does it happen? And what can we do to manage symptoms when winter inevitably returns?
What Is Seasonal Affective Disorder?
Seasonal Affective Disorder (SAD) is a subtype of major depressive disorder with a seasonal pattern, most commonly occurring during the fall and winter months when daylight hours decrease (American Psychiatric Association, 2022).
For a smaller number of individuals, depressive symptoms occur during the spring or summer, though winter-onset SAD is far more common.
Clinically, Seasonal Affective Disorder is diagnosed when depressive episodes:
Occur at a specific time of year
Persist for several months
Improve or resolve when the season changes
It is also important to distinguish SAD from the winter blues, which are relatively common and typically milder. In contrast, Seasonal Affective Disorder involves more significant symptoms that interfere with daily functioning.
Common symptoms include:
Persistent sadness or low mood
Irritability
Anxiety
Oversleeping or difficulty waking up
Appetite changes, particularly cravings for carbohydrates
Weight gain
Low energy or fatigue
Social withdrawal
Feelings of hopelessness or worthlessness
For many individuals, these symptoms last approximately four to five months each year.
Why Does Winter Affect Mental Health?
Seasonal Affective Disorder, which some call seasonal depression, is linked to several biological and environmental factors.
Reduced sunlight during the winter months can disrupt the body’s circadian rhythm, which regulates sleep and wake cycles (Lam & Levitt, 1999).
Lower exposure to natural light may also influence the production of key brain chemicals, including:
Serotonin, which plays a central role in mood regulation
Melatonin, which regulates sleep patterns
Vitamin D, which has been associated with mood and immune functioning
When daylight hours decrease, these systems can become disrupted, leading to changes in sleep, energy levels, and mood.
This is one reason why Seasonal Depression is more common in northern regions like New York City, where winter days are shorter and sunlight exposure is limited.
Who Is Most at Risk for Seasonal Depression?
Certain individuals may be more vulnerable to Seasonal Affective Disorder.
Research suggests higher risk among:
People living farther from the equator
Individuals with a history of depression or bipolar disorder
People with a family history of mood disorders
Women and younger adults
Individuals who spend most daylight hours indoors
For many professionals in cities like New York, winter routines often involve leaving home before sunrise and returning after sunset, further reducing exposure to natural light.
Evidence-Based Treatments for Seasonal Affective Disorder
The encouraging news is that Seasonal Affective Disorder is highly treatable. Several interventions have strong research support.
1. Light Therapy
Light therapy is one of the most widely studied treatments for Seasonal Affective Disorder.
It involves sitting near a 10,000-lux light box that mimics natural outdoor light. This exposure helps regulate circadian rhythms and supports serotonin production (Golden et al., 2005).
Most individuals use light therapy for 20–30 minutes each morning, ideally shortly after waking.
2. Cognitive Behavioral Therapy (CBT)
Psychotherapy—particularly Cognitive Behavioral Therapy (CBT) and CBT adapted specifically for SAD (CBT-SAD)—is highly effective for treating seasonal depression (Rohan et al., 2015).
CBT helps individuals:
Identify negative thought patterns
Increase engagement in mood-boosting activities
Develop coping strategies for seasonal stress
Build routines that support mental health during darker months
Many people find that CBT provides tools they can continue using each winter.
3. Medication
For some individuals, antidepressant medications, particularly selective serotonin reuptake inhibitors (SSRIs), can help regulate mood during seasonal depressive episodes (Lam et al., 2006).
A psychiatrist or primary care physician can help determine whether medication is appropriate.
4. Increasing Natural Light Exposure
Even on cloudy winter days, outdoor light is significantly brighter than indoor lighting.
Taking a walk during daylight hours or spending time outdoors during lunch can help support circadian rhythms and improve mood.
5. Physical Activity
Regular physical activity plays an important role in mood regulation. Exercise increases endorphins and neurotransmitters associated with improved emotional well-being while also improving sleep quality.
Consistent movement—such as walking, yoga, or stretching—can have meaningful benefits.
6. Maintaining a Consistent Sleep Schedule
Shorter days can easily disrupt sleep patterns.
Maintaining a consistent sleep schedule, even on weekends, helps regulate the body’s internal clock and can reduce fatigue and mood fluctuations.
7. Balanced Nutrition
Many individuals with winter depression experience stronger cravings for carbohydrates and comfort foods. This response has biological underpinnings.
Balanced meals that include protein, fiber, and healthy fats can help stabilize blood sugar levels and energy throughout the day.
8. Maintaining Social Connection
Seasonal depression often increases the urge to withdraw socially.
While this instinct is understandable, maintaining social connection can be an important protective factor for mental health. Even low-pressure interactions—such as meeting a friend for coffee or having a phone call—can help reduce feelings of isolation.
Why Preparing Before Winter Can Help
If winter historically affects your mood, the best time to prepare may actually be when you are feeling well.
When symptoms begin in the fall, motivation to start supportive habits can decrease, making it harder to implement the very strategies that could help.
Preparing in advance may include:
Purchasing and setting up a light therapy box
Scheduling therapy appointments
Creating a winter wellness routine
Planning social activities during darker months
Discussing preventive medication with a psychiatrist
Early intervention can significantly reduce the severity of seasonal depressive symptoms.
When to Seek Support
If you notice significant changes in mood, sleep, energy, or motivation during the winter months, professional support can help.
At Upper East Side Psychology, our clinicians provide evidence-based treatment for seasonal depression using approaches such as:
Cognitive Behavioral Therapy (CBT)
Behavioral activation
Mood and routine interventions
Structured coping strategies
Therapy can help individuals develop practical tools to manage seasonal mood changes and maintain well-being throughout the year.
Final Thoughts
One of the unique aspects of Seasonal Affective Disorder is that it tends to be predictable.
If winter has historically been difficult, chances are it may be again—but that predictability also allows us to prepare.
Building supportive habits and resources before symptoms begin can significantly reduce their impact.
And if you’re currently enjoying this unexpected stretch of sunshine in New York City, consider it a reminder of how powerful light—and proactive care—can be for mental health.
For now, enjoy the sunshine.
References
American Psychiatric Association. (2022). Diagnostic and Statistical Manual of Mental Disorders (5th ed., text rev.).
Golden, R. N., Gaynes, B. N., Ekstrom, R. D., et al. (2005). The efficacy of light therapy in the treatment of mood disorders. American Journal of Psychiatry, 162(4), 656–662.
Lam, R. W., & Levitt, A. J. (1999). Canadian consensus guidelines for the treatment of seasonal affective disorder.Clinical & Academic Publishing.
Lam, R. W., Levitt, A. J., Levitan, R. D., et al. (2006). The CAN-SAD study: A randomized controlled trial of the effectiveness of light therapy and fluoxetine in patients with seasonal affective disorder. American Journal of Psychiatry, 163(5), 805–812.
Rohan, K. J., Roecklein, K. A., Haaga, D. A., et al. (2015). Randomized trial of cognitive-behavioral therapy versus light therapy for seasonal affective disorder. American Journal of Psychiatry, 172(9), 862–869.
Rosenthal, N. E., Sack, D. A., Gillin, J. C., et al. (1984). Seasonal affective disorder: A description of the syndrome and preliminary findings with light therapy. Archives of General Psychiatry, 41(1), 72–80.
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