Seasonal Depression (Seasonal Affective Disorder)

Seasonal depression, also called seasonal affective disorder (SAD), is a type of depression. It’s triggered by the change of seasons and most commonly begins in late fall. Symptoms include feelings of sadness, lack of energy, loss of interest in usual activities, oversleeping and weight gain. Treatments include light therapy, talk therapy and antidepressants.


What is seasonal affective disorder (SAD)?

Seasonal affective disorder (SAD) is a type of depression triggered by a change in seasons, usually when fall starts. This seasonal depression gets worse in the late fall or early winter before ending in the sunnier days of spring.

You can also get a mild version of SAD known as the “winter blues.” It’s normal to feel a little down during colder months. You may be stuck inside, and it gets dark early.

But full SAD goes beyond this. It’s a form of depression. Unlike the winter blues, SAD affects your daily life, including how you feel and think. Fortunately, treatment can help you get through this challenging time.

Your healthcare provider may refer to seasonal affective disorder as seasonal depression.

Can people get seasonal affective disorder (SAD) in the summer?

Some people get a rare form of SAD called “summer depression.” It starts in the late spring or early summer and ends in the fall. It’s less common than the seasonal affective disorder that tends to come during winter.

How common is seasonal affective disorder (SAD)?

About 5% of adults in the U.S. experience SAD. It tends to start in young adulthood (usually between the ages of 18 and 30). SAD affects people assigned female at birth more than people assigned male at birth, though researchers aren’t sure why.

About 10% to 20% of people in America may get a milder form of the winter blues.


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Symptoms and Causes

What are the symptoms of seasonal affective disorder (SAD)?

Seasonal affective disorder (SAD) is a type of depression. The American Psychiatric Association officially classifies SAD as major depressive disorder with seasonal patterns. So if you have seasonal affective disorder, you may experience mood changes and symptoms of depression, including:

  • Sadness, feeling depressed most of the day, almost every day.
  • Anxiety.
  • Carbohydrate cravings and weight gain.
  • Extreme fatigue and lack of energy.
  • Feelings of hopelessness or worthlessness.
  • Trouble concentrating.
  • Feeling irritated or agitated.
  • Limbs (arms and legs) that feel heavy.
  • Loss of interest in usually pleasurable activities, including withdrawing from social activities.
  • Sleeping problems (usually oversleeping).
  • Thoughts of death or suicide.

People who have summer SAD may experience:

  • Agitation and restlessness.
  • Anxiety.
  • Decreased appetite and weight loss.
  • Episodes of violent behavior.
  • Trouble sleeping (insomnia).

What causes seasonal affective disorder (SAD)?

Researchers don’t know exactly what causes seasonal depression. Lack of sunlight may trigger the condition if you’re prone to getting it. The theories suggest:

  • Biological clock change: When there’s less sunlight, your biological clock shifts. This internal clock regulates your mood, sleep and hormones. When it shifts, you’re out of step with the daily schedule you’ve been used to and can’t adjust to changes in daylight length.
  • Brain chemical imbalance: Brain chemicals called neurotransmitters send communications between nerves. These chemicals include serotonin, which contributes to feelings of happiness. If you’re at risk of SAD, you may already have less serotonin activity. Since sunlight helps regulate serotonin, a lack of sunlight in the winter can make the situation worse. Serotonin levels can fall further, leading to depression.
  • Vitamin D deficiency: Your serotonin level also gets a boost from vitamin D. Since sunlight helps produce vitamin D, less sun in the winter can lead to a vitamin D deficiency. That change can affect your serotonin level and your mood.
  • Melatonin boost: Melatonin is a chemical that affects your sleep patterns and mood. The lack of sunlight may stimulate an overproduction of melatonin in some people. You may feel sluggish and sleepy during the winter.
  • Negative thoughts: People with SAD often have stress, anxiety and negative thoughts about the winter. Researchers aren’t sure if these negative thoughts are a cause or effect of seasonal depression.

Who is at risk for seasonal affective disorder (SAD)?

Seasonal affective disorder (SAD) is more common in people between 18 and 30 and people assigned female at birth. You’re also at higher risk if you:

  • Have another mood disorder, such as major depressive disorder or bipolar disorder.
  • Have relatives with SAD, other forms of depression or mental health conditions, such as major depression or schizophrenia.
  • Live at latitudes far north or far south from the equator. There’s less sunlight during the winter at these latitudes.
  • Live in cloudy regions.


Diagnosis and Tests

How is seasonal affective disorder (SAD) diagnosed?

If you have symptoms of seasonal affective disorder (SAD), don’t try to diagnose yourself. See your healthcare provider for a thorough evaluation. You may have another reason for your depression. Many times, seasonal affective disorder is part of a more complex mental health condition.

Your provider may refer you to a psychiatrist or psychologist. These mental health professionals will ask you about your symptoms. They’ll consider your pattern of symptoms and decide if you have seasonal depression or another mood disorder. You may need to fill out a questionnaire to determine if you have SAD.

What tests will I need to diagnose seasonal affective disorder (SAD)?

There’s no blood test or scan to diagnose seasonal depression. Still, your provider may recommend testing to rule out other conditions that cause similar symptoms, including testing your thyroid to make sure it’s functioning properly.

What are the criteria for a seasonal affective disorder (SAD) diagnosis?

Your provider may diagnose you with SAD if you have:

  • Symptoms of major depression.
  • Depressive episodes that occur during specific seasons for at least two consecutive years.
  • Depressive episodes happening more frequently during a specific season than during the rest of the year.

Management and Treatment

How is seasonal affective disorder (SAD) treated?

Your provider will talk to you about treatment options. You may need a combination of treatments, including:

  • Light therapy: Bright light therapy, using a special lamp, can help treat SAD.
  • Cognitive behavioral therapy (CBT): CBT is a type of talk therapy. Research has shown it effectively treats SAD, producing the longest-lasting effects of any treatment approach.
  • Antidepressant medication: Sometimes, providers recommend medication for depression, either alone or with light therapy.
  • Spending time outdoors: Getting more sunlight can help improve your symptoms. Try to get out during the day. Also, increase the amount of sunlight that enters your home or office.
  • Vitamin D: A vitamin D supplement may help improve your symptoms. Talk to your provider before starting this supplement.

How does light therapy work?

To use light therapy or phototherapy, you purchase a special lamp. It has white fluorescent light tubes covered with a plastic screen to block ultraviolet rays. The light is about 20 times brighter than regular indoor light. The intensity of light emitted should be 10,000 lux.

To use phototherapy, don’t look directly into the light. Your exposure to the light should be indirect. Place the lamp about two to three feet away while you read, eat, work or do other activities.

What time of day should I use light therapy?

The time of day you use light therapy may impact how effective it is. Morning light therapy seems to work best. Using light therapy later in the day may cause insomnia. Many health professionals recommend 10,000 lux for 15 to 30 minutes every morning.

How long will it take light therapy to work?

People who use a lamp for SAD often see results within two to four days. It may take about two weeks to reach its full benefits.

How long do I continue to use light therapy?

Healthcare providers often recommend using light therapy throughout the entire winter. SAD symptoms can return quickly after stopping light therapy. Continuing to use the therapy can help you feel your best throughout the season.

Is light therapy safe?

Light therapy is typically safe and well-tolerated. But you may need to avoid light therapy if you:

  • Have diabetes or retinopathies: If you have diabetes or a retina condition, there’s a potential risk of damaging the retina, the back of your eye.
  • Take some medications: Certain antibiotics and anti-inflammatories can make you more sensitive to sunlight. Light therapy can then cause harm.
  • Have bipolar disorder: Bright light therapy and antidepressants can trigger hypomania or mania, uncontrolled boosts in mood and energy level. If you have bipolar disorder, let your provider know. This will play a role in your treatment plan.
What are the side effects of light therapy?

You may experience:

Can I use a tanning bed instead of light therapy to treat seasonal affective disorder (SAD)?

Don’t use tanning beds to treat SAD. Tanning beds do generate enough light, but they can cause other harm. They produce a high amount of ultraviolet (UV) rays that can hurt your skin and eyes.

What type of antidepressants can help with seasonal affective disorder (SAD)?

Medications called selective serotonin reuptake inhibitors (SSRIs) can treat SAD. They improve your mood by regulating serotonin levels in your body.

Examples of some SSRIs include:

  • Fluoxetine (Prozac®).
  • Escitalopram (Lexapro®).
  • Paroxetine (Paxil, Pexeva®).
  • Sertraline (Zoloft®).
  • Citalopram (Celexa®).

Another approved antidepressant called bupropion comes as an extended-release tablet. It can prevent seasonal depression episodes if taken daily from fall to early spring.



Can I prevent seasonal affective disorder (SAD)?

You may not be able to prevent the first episode of SAD. But once your provider diagnoses you with seasonal depression, you can take steps to better manage it or even prevent it from coming back.

  • Use your lightbox: Start using light therapy at the beginning of fall, before you feel SAD symptoms.
  • Get out: Spend time outside every day, even if it’s cloudy. Daylight can help you feel better.
  • Eat nutritious meals: Even though your body may crave starchy and sweet foods, stick to nutritious choices. Healthy foods with enough vitamins and minerals can give you the proper nutrition and energy you need.
  • Exercise: Try to get 30 minutes of exercise at least three times a week. Exercise relieves stress and anxiety, which can play a role in your SAD symptoms.
  • See friends: Stay involved with your social circle and regular activities. They can provide support during the winter months.
  • Find help: Consider seeing a mental health professional who’s trained in CBT. This treatment can be very effective for seasonal affective disorder.
  • Consider medications: Talk to your healthcare provider about taking an antidepressant. Medications can help if your symptoms are severe or if they continue after other treatments. In some cases, taking the medication before SAD begins can prevent episodes.

Talk to your healthcare provider to find out if starting treatment early, as a preventive measure, is right for you.

Outlook / Prognosis

What’s the outlook for people with seasonal affective disorder (SAD)?

If you have seasonal affective disorder, the outlook is positive. Treatments are available for SAD. People who get the right diagnosis and combination of treatments can find relief from symptoms. Talk to your healthcare provider to figure out the treatment that will work best for you.

Can seasonal affective disorder (SAD) come back?

People who are prone to seasonal affective disorder can get it every year, but you can take steps to prevent or lessen symptoms.

Living With

How can I best take care of myself if I have seasonal affective disorder?

Talk to your healthcare provider. By planning ahead, you can manage your symptoms and feel your best.


  • Stick to your treatment plan: If you have medications or a lamp for SAD, use them as directed. Follow up with your healthcare provider if you don’t see an improvement in your symptoms.
  • Care for yourself: Eat well-balanced meals. Get enough sleep. Exercise regularly. Try to manage stress, perhaps by talking to a counselor or therapist.
  • Plan ahead: Make a plan for what you’ll do if your symptoms get worse. If you notice signs of depression, take action. It might help to plan a lot of activities during these months. Having a busy schedule keeps you from hunkering down at home.
  • Start treatment early: Talk to your healthcare provider about preventive treatment. If you know your symptoms start in October, consider starting treatment in September.


  • Isolate yourself: Being alone can make your symptoms worse. Even though you may not feel like going out or being social, try to reach out to friends and loved ones.
  • Use alcohol or unprescribed drugs: They might make symptoms worse, and they can interact negatively with antidepressants.

When should I see my healthcare provider about seasonal affective disorder (SAD)?

If you think you have symptoms of seasonal depression or another mood disorder, see your healthcare provider. Your provider will want to rule out another condition or illness that may be causing these symptoms.

When should I go to the emergency room?

If you or a loved one has suicidal thoughts, get help. Call your provider, go to an emergency room, call 911 or call the Suicide and Crisis Lifeline, at 988. This national network of local crisis centers provides free, confidential emotional support to people in suicidal crisis or emotional distress. It’s available 24/7.

What should I ask my healthcare provider?

If you have SAD, ask your provider:

  • What treatment is best for me?
  • How can I prevent depressive episodes?
  • Will light therapy work?
  • Should I take an antidepressant?
  • When should I start treatment?
  • How long should my treatment continue?
  • What can I eat (or should avoid eating) to improve my symptoms?
  • What else can I do to feel better?

A note from Cleveland Clinic

Seasonal affective disorder (SAD) is a type of depression that happens every year during a specific season, usually winter. Symptoms can include a lack of energy and feelings of hopelessness. Fortunately, there’s treatment for seasonal depression. Talk to your healthcare provider. They’re there to help.

Medically Reviewed

Last reviewed on 04/10/2022.

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