Seasonal depression, also called Seasonal Affective Disorder (SAD), is a type of depression that occurs at the same time every year. Most commonly, it begins in the fall or winter and fades during spring or early summer.
Each year, over 11 million Americans experience SAD. Another 25 million may suffer from a milder version often referred to as the “winter blues.”
Can It Happen in Summer?
Yes, a less common type known as summer depression starts in late spring or early summer and ends in the fall.
What Causes Seasonal Depression?
Although the exact cause is unclear, scientists believe hormonal shifts in the brain play a key role.
Less sunlight in fall and winter may lower serotonin levels — a brain chemical that influences mood. Disrupted circadian rhythms and melatonin levels can also contribute to feelings of sadness and fatigue.
SAD is more common in:
- Women
- Young adults
- People living in areas with shorter daylight hours
In contrast, summer SAD might be triggered by increased heat, longer days, and changes in social patterns or expectations.
Seasonal Depression Symptoms
Common Symptoms
- Persistent sadness or low mood
- Fatigue and low energy
- Trouble concentrating
- Craving carbohydrates
- Oversleeping
- Weight gain
- Withdrawing from social activities
- Feelings of hopelessness or guilt
- Thoughts of self-harm or suicide
Winter SAD
- Oversleeping
- Increased appetite, especially for starchy foods
- Low energy
- Avoiding social interaction
Summer SAD
- Insomnia
- Anxiety or irritability
- Poor appetite and weight loss
- Restlessness or aggression
How Is Seasonal Depression Diagnosed?
SAD is a form of major depression or bipolar disorder that occurs seasonally.
A diagnosis is likely if you’ve experienced:
- Depression that begins and ends during a specific season for at least two years
- No symptoms during other times of the year
- More seasons with symptoms than without
Your doctor may conduct:
- A physical exam
- Blood tests to rule out other conditions
- A psychological evaluation
- A symptom questionnaire
Seasonal Depression Treatment
Medication
Antidepressants, including bupropion XL (approved for SAD), may help. Doctors often recommend starting them before symptoms typically begin.
Therapy
Cognitive behavioral therapy (CBT) can help you manage symptoms and develop coping strategies.
Vitamin D
Low vitamin D levels are common in people with SAD. While supplements might help, more research is needed.
Light Therapy
Light therapy is one of the most effective treatments for winter SAD.
You sit near a bright light box (10,000 lux) that mimics natural sunlight. Sessions start at 10–15 minutes per day and increase to 30–45 minutes.
Some people improve within days, while others may take longer. If needed, the doctor may recommend two sessions daily. Continue therapy through winter until natural daylight increases.
Choosing a Light Therapy Lamp
Use a device that emits at least 10,000 lux with minimal UV exposure. Consult your doctor before use.
Possible Side Effects
Side effects are usually minimal but can include:
- Eye strain
- Headaches
- Mania (in people with bipolar disorder)
People with eye conditions like cataracts or glaucoma should use caution. Never look directly into the light.
Outdoor Activity
Doctors often suggest spending more time outdoors, especially in the morning. When that’s not possible, light therapy or medication may help.
Seasonal Depression Prevention
There’s limited research on prevention, but these steps may reduce risk:
- Get daily daylight exposure, even when cloudy
- Start light therapy in early fall, before symptoms begin
- Eat a balanced diet
- Exercise regularly (30 minutes, 5 times a week)
- Stay socially active
- Follow your doctor’s guidance on medication use
Living With Seasonal Depression
Helpful habits include:
- Seeking professional help early
- Maintaining consistent sleep and wake times
- Maximizing indoor natural light exposure
- Scheduling enjoyable activities
- Avoiding alcohol and drugs
- Managing your workload and expectations
- Reaching out to supportive friends or family
- Being patient — recovery can take time
When Should I Call My Doctor?
If you feel depressed, fatigued, or irritable during specific seasons, talk to your doctor. Early treatment and lifestyle changes can make a big difference.
Ask if your clinic offers light boxes or whether purchasing one is appropriate. Keep in mind that health insurance typically does not cover them.
Takeaways
Seasonal depression is a recurring mood disorder that affects how you feel and function during certain times of the year. Recognizing the signs, getting proper treatment, and adopting healthy lifestyle habits can help you manage symptoms and improve your quality of life.
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