Seasonal Affective Disorder: When the Seasons Affect Your Mood

As the days get shorter and sunlight becomes scarce, many people notice changes in their energy, sleep, and mood. For some, these changes go beyond “winter blues” and become a form of depression known as Seasonal Affective Disorder (SAD). The good news: SAD is common, treatable, and there are practical steps you can take—often starting today.

What Is Seasonal Affective Disorder (SAD)?

Seasonal Affective Disorder is a type of depression that follows a seasonal pattern. Most often, symptoms begin in the fall or winter and improve in the spring and summer. Less commonly, some people experience “summer-pattern” SAD, where symptoms worsen during late spring or summer.

SAD is not a character flaw or a lack of willpower. It’s a real, biologically influenced condition that can affect thoughts, emotions, and daily functioning.

Signs and Symptoms to Watch For

SAD can look different from person to person, but common symptoms include:

• Low mood most of the day, nearly every day
• Loss of interest in activities you usually enjoy
• Low energy or feeling “slowed down”
• Changes in sleep, often sleeping more than usual
• Increased appetite, especially cravings for carbs or sweets
• Weight gain
• Difficulty concentrating or “brain fog”
• Irritability
• Feeling hopeless, guilty, or overly self-critical

If symptoms include thoughts of self-harm or suicide, seek help immediately—call 988 in the U.S. or go to the nearest emergency department.

Why Does SAD Happen?

Researchers are still studying the exact causes, but several factors likely play a role—especially in winter-pattern SAD:

• Reduced sunlight exposure, which can disrupt the body’s internal clock (circadian rhythm)
• Changes in serotonin, a brain chemical linked to mood regulation
• Changes in melatonin, which influences sleep and wake cycles
• Lifestyle changes in winter (less activity, less social connection, more time indoors)

SAD can affect anyone, but risk can be higher if you:

• Have a personal or family history of depression or bipolar disorder
• Live farther from the equator (less winter daylight)
• Have symptoms that return in the same season year after year

SAD vs. “Winter Blues”: What’s the Difference?

Many people feel a little less motivated or energized in winter. The key difference is severity and impairment.

Winter blues might mean you feel “off” but can still function.
SAD typically involves symptoms that persist for weeks and interfere with work, school, relationships, or self-care.

If you’re unsure, it’s worth talking with a clinician—especially if this pattern repeats annually.

Treatment Options That Work

SAD is very treatable, and many people feel significantly better with the right plan. Common evidence-based approaches include:

Light Therapy

Light Therapy uses a bright light box (typically 10,000 lux) for a short period daily—often in the morning. Many people notice improvement within 1–2 weeks.

Tips:

• Use the device consistently every day during the season
• Follow product instructions and medical guidance—especially if you have eye conditions or bipolar disorder

Talk Therapy (Especially CBT)

Cognitive Behavioral Therapy (CBT) can be very effective for SAD. It focuses on identifying patterns that keep depression going and building skills to improve mood, routines, and resilience through the season.

Medication

Antidepressants can be helpful for SAD, particularly when symptoms are moderate to severe or recurring each year. In some cases, clinicians may recommend starting medication before symptoms typically begin.

Important: If you have a history of bipolar disorder (or possible bipolar symptoms), discuss this with your provider before starting an antidepressant, as treatment planning may differ.

Vitamin D (When Appropriate)

Some people with low vitamin D levels feel worse in winter. Supplementation may help if you’re deficient. A clinician can guide testing and dosing.

Practical Self-Care Strategies for the Season

Treatment works best when paired with supportive daily habits. Consider trying a few of these:

Get outside early in the day, even if it’s cloudy (outdoor light still helps)

• Keep a consistent sleep schedule, aiming for the same wake time daily
• Move your body regularly (even short walks help)
• Plan social connection—depression often pushes people to isolate
• Create a “winter routine” that includes small enjoyable activities
• Limit alcohol, which can worsen mood and sleep
• Be gentle with yourself—SAD is not laziness; it’s a health condition

When to Reach Out for Help

Consider reaching out if:

• Symptoms last more than two weeks
• You’re struggling to function at work, school, or home
• You are withdrawing from people you care about
• Your sleep, appetite, or motivation has changed significantly
• You have dealt with similar symptoms in past winters

Getting support early can prevent symptoms from escalating and make the season feel more manageable.

How Our Clinic Can Help

If you think you may be experiencing Seasonal Affective Disorder, you don’t have to navigate it alone. Our clinic can help with:

• Screening and diagnosis
• Personalized treatment planning
• Therapy referrals and coping-skill support
• Medication options when appropriate
• Guidance on safe, effective light therapy use

If you’d like to talk with a provider, contact our office to schedule an appointment. Early support can make a meaningful difference—especially before symptoms become overwhelming.

Schedule Appointment

This blog is for educational purposes and is not a substitute for individualized medical advice. If you are in crisis or having thoughts of self-harm, call 988 (U.S.) or your local emergency number right away.