Seasonal Affective Disorder

The most recognizable signs of winter SAD are persistent low mood, hopelessness, fatigue, low energy, irritability, increased appetite and sleep, social withdrawal, and difficulty concentrating. Some people experience suicidal thoughts. Summer SAD presents differently — with reduced appetite, weight loss, insomnia, agitation, and restlessness — though feelings of worthlessness and hopelessness are still common. A defining feature of SAD is the seasonal pattern: symptoms arrive predictably at the same time each year and resolve in the opposite season.

A doctor diagnoses SAD by looking for three key criteria: depression or mania that repetitively begins and ends at the same times each year; symptoms that self-resolve during the “normal” (warmer) season; and symptoms that have repeated for at least 2 consecutive years. Because SAD shares symptoms with bipolar disorder, chronic fatigue syndrome, hypoglycemia, certain viral illnesses, and thyroid conditions, a doctor will rule these out before confirming a SAD diagnosis. Tracking your symptoms daily and rating them on a 0–10 scale before your appointment can be helpful.

A primary care physician, psychiatrist, psychologist, or licensed clinical therapist can diagnose SAD. A primary care doctor is typically the starting point — they can rule out physical health causes (thyroid issues, viral illness, blood sugar problems) and refer to a mental health specialist if needed. Because SAD overlaps with several other conditions, an accurate diagnosis requires a thorough medical and mental health history.

Yes. Licensed therapists and psychiatrists practicing via telehealth can evaluate and diagnose SAD. Online therapy is also an effective treatment option — CBT is particularly well-suited to online delivery and is one of the most evidence-based approaches for seasonal depression.

Cognitive behavioral therapy (CBT) is the most evidence-based therapy for SAD. It helps identify and restructure the negative thought patterns that drive seasonal depression and builds coping skills for getting through the difficult season. Talking with a therapist who specializes in SAD is a strong starting point. For many people, therapy works best in combination with light therapy and/or medication.

Seek professional help if you notice a recurring pattern of low mood, fatigue, social withdrawal, changes in appetite or sleep, or difficulty functioning that arrives at the same time each year — particularly in autumn or winter. Don’t wait for symptoms to become severe. If you are experiencing suicidal thoughts, seek help immediately. Tracking your daily symptoms on a 0–10 scale before your first appointment can help your provider assess severity and pattern. You are not alone — an estimated 10 million Americans experience SAD each year.

Yes. SAD is highly treatable, and symptoms do not have to rule your life. Therapy (especially CBT), medication (antidepressants or beta-blockers), and light therapy are all effective and are often most powerful in combination. Treatment plans are tailored to symptom severity and frequency.

SAD is quite common. Research shows an estimated 5% of people in the U.S. — approximately 10 million Americans — struggle with SAD every year. As many as 25 million more may experience a milder form known as “winter blues.” For most, the seasonal pattern begins in late autumn or early winter and continues into late spring or early summer. If you’re experiencing symptoms, tracking them daily and reaching out to a therapist is a good first step.