Published
Medically reviewed by Danesh Alam MD, DFAPA, DFASAM
Seasonal affective disorder (SAD) is a type of depression that returns at the same time each year, most often in late fall and winter, and lifts in spring. Symptoms include low mood, low energy, oversleeping, and carbohydrate cravings. It is treatable with light therapy, talk therapy, and medication, and it can affect people in Florida too.
If you or someone you love is thinking about suicide, call or text 988 to reach the 988 Suicide and Crisis Lifeline. In a life-threatening situation, call 911. NIMH: Seasonal Affective Disorder
What is seasonal affective disorder?
Seasonal affective disorder is depression with a recurring seasonal pattern. Symptoms last about four to five months of the year. In most cases they start in late fall or early winter and go away during spring and summer. This is called winter-pattern SAD. Some people instead have symptoms in spring and summer, known as summer-pattern SAD, which is less common. NIMH: Seasonal Affective Disorder
SAD is not a separate diagnosis. In the DSM-5-TR, the manual clinicians use to diagnose mental health conditions, it is listed as a type of depression: major depressive disorder with seasonal pattern. American Psychiatric Association: Seasonal Affective Disorder (SAD) The same "with seasonal pattern" label can also be applied to bipolar disorder. Psychiatria Polska: Forty years of seasonal affective disorder
In other words, seasonal depression is depression, and it deserves the same care.
The American Psychiatric Association estimates that about 5% of adults in the United States experience SAD. It can begin at any age but typically starts between ages 18 and 30. American Psychiatric Association: Seasonal Affective Disorder (SAD)
What are the symptoms of seasonal depression?
The symptoms of seasonal depression are the symptoms of depression, plus a few that differ by season. Not every person has all of them. General symptoms of depression can include:
- A sad, anxious, or "empty" mood most of the day, nearly every day, for at least two weeks
- Feeling hopeless, guilty, worthless, or irritable
- Losing interest in hobbies and activities
- Low energy, fatigue, or feeling slowed down
- Trouble concentrating, remembering, or making decisions
- Changes in sleep, appetite, or weight
- Aches, pains, or digestive problems with no clear physical cause
- Thoughts of death or suicide
Winter-pattern SAD can add:
- Oversleeping
- Overeating, especially craving carbohydrates, with weight gain
- Pulling away from other people, sometimes described as feeling like "hibernating"
Summer-pattern SAD can add:
- Trouble sleeping
- Poor appetite and weight loss
- Restlessness, agitation, and anxiety
- In some cases, violent or aggressive behavior
NIMH: Seasonal Affective Disorder
Winter symptoms usually build slowly through late autumn and winter. MedlinePlus: Seasonal affective disorder In the United States, January and February tend to be the hardest months. American Psychiatric Association: Seasonal Affective Disorder (SAD) Our guide to the signs of depression covers the general symptoms in more detail.
Is it seasonal affective disorder or the winter blues?
The difference is severity. Many people feel "down" when the days get shorter and feel better in spring. NIMH describes SAD as the point where those changes are more serious and affect how a person feels, thinks, and behaves. NIMH: Seasonal Affective Disorder The American Psychiatric Association puts it plainly: SAD is "more than just 'winter blues,'" and its symptoms can interfere with daily functioning. American Psychiatric Association: Seasonal Affective Disorder (SAD)
Some people keep working and showing up while feeling this way, which can hide how hard things are. We describe that pattern in what high-functioning depression looks like.
Are the holiday blues the same as SAD?
No. NIMH says winter-pattern SAD "should not be confused with 'holiday blues,'" which are feelings of sadness or anxiety brought on by stress at certain times of year. SAD is tied to changes in daylight hours, not to the calendar. NIMH: Seasonal Affective Disorder
What causes seasonal affective disorder?
The exact cause is not known. Researchers are still working it out, and most studies have looked at winter-pattern SAD because it is more common and easier to study. NIMH describes three leading ideas:
- Serotonin. Studies indicate that people with SAD, especially the winter pattern, have reduced levels of serotonin, a brain chemical that helps regulate mood. Shorter days may play a part.
- Melatonin. People with winter-pattern SAD may make too much melatonin, a hormone tied to the sleep-wake cycle, which can increase sleepiness.
- Vitamin D. Low vitamin D may make these problems worse, because vitamin D is believed to support serotonin activity.
For summer-pattern SAD, long, hot days and short nights may disrupt sleep, but NIMH notes these theories "have not been systematically tested." NIMH: Seasonal Affective Disorder
What is better established is the link to latitude. A 2025 analysis of 24 studies found that SAD becomes more common the farther people live from the equator. Journal of Affective Disorders: Global prevalence of SAD by latitude
Who is at risk for seasonal affective disorder?
SAD occurs much more often in women than in men, and in most cases it begins in young adulthood. Risk is also higher for people who:
- Live farther north, where winter days are shorter
- Have depression or bipolar disorder, especially bipolar II disorder
- Have another mental health condition, such as ADHD, an eating disorder, an anxiety disorder, or panic disorder
- Have relatives with SAD or other mental illnesses, such as depression or schizophrenia
NIMH: Seasonal Affective Disorder
Can you get seasonal affective disorder in Florida?
Yes, although winter-pattern SAD is less common in Florida than in northern states. NIMH uses the state as its example: people in Alaska or New England are more likely to develop SAD than people in Texas or Florida. NIMH: Seasonal Affective Disorder
Exact numbers for Florida are thin. One 2015 review cites an estimate that about 1% of people in Florida experience SAD, compared with about 9% in Alaska. Depression Research and Treatment: Seasonal affective disorder overview That figure traces back to questionnaire research from decades ago, so treat it as a rough guide.
Summer-pattern SAD is a different story. The 2025 analysis found it in well under 1% of people overall, and it found no link between latitude and the summer pattern. Journal of Affective Disorders: Global prevalence of SAD by latitude An earlier US survey that included Sarasota, Florida, reached the same conclusion. Psychiatry Research: Prevalence of SAD at four latitudes In other words, living in the South does not appear to protect against the summer type.
One more point for Floridians: depression that is not seasonal can start at any time of year, including winter. Symptoms that last for weeks deserve attention whatever the label turns out to be.
How is seasonal affective disorder diagnosed?
There is no lab test for SAD. A health care provider makes the diagnosis by asking about your history of symptoms, and may do a physical exam and blood tests to check for other conditions with similar symptoms. MedlinePlus: Seasonal affective disorder Thyroid problems are one example of a condition that can be mistaken for SAD. American Psychiatric Association: Seasonal Affective Disorder (SAD)
According to NIMH, a diagnosis of SAD requires:
- Symptoms of depression, or the more specific winter-pattern or summer-pattern symptoms
- Depressive episodes that occur in a specific season for at least two years in a row
- Seasonal episodes that are more frequent than episodes at other times of the year
Not everyone with SAD has symptoms every year. NIMH: Seasonal Affective Disorder
Tell the clinician about any history of bipolar disorder, because it can affect which treatments are appropriate. Our guide to what a mental health assessment involves explains what to expect.
How is seasonal affective disorder treated?
Treatment falls into four main categories, used alone or together: light therapy, psychotherapy, antidepressant medication, and vitamin D. Light therapy and vitamin D are used for winter-pattern SAD. Psychotherapy and antidepressants treat depression in general, including both patterns. There are no treatments specific to summer-pattern SAD. NIMH: Seasonal Affective Disorder
Light therapy
Light therapy has been a mainstay for winter-pattern SAD since the 1980s. A person sits in front of a very bright light box each day, usually first thing in the morning, from fall to spring. NIMH describes the box as about 20 times brighter than ordinary indoor light, with a filter for potentially damaging UV light. NIMH: Seasonal Affective Disorder
Talk with a clinician before starting light therapy. Side effects can include eye strain, headache, and, rarely, mania. An eye checkup is recommended first, and people who take medicines that make them more sensitive to light should not use it. MedlinePlus: Seasonal affective disorder Light therapy may also not be appropriate for people with diseases of the retina, recent eye surgery, or bipolar disorder. NCCIH: Seasonal Affective Disorder
Talk therapy
Cognitive behavioral therapy (CBT) helps people challenge and change unhelpful thoughts and behaviors. A version adapted for SAD, called CBT-SAD, focuses on negative thoughts about the season. It also uses behavioral activation: planning pleasant, engaging activities to offset the loss of interest. NIMH: Seasonal Affective Disorder
In a randomized trial of 177 adults, CBT-SAD and light therapy improved symptoms comparably during the first winter. American Journal of Psychiatry: CBT-SAD versus light therapy Two winters later, depression had returned for fewer of the people who received CBT-SAD. American Journal of Psychiatry: Outcomes one and two winters later
Antidepressant medication
Antidepressants can be effective for SAD, alone or combined with talk therapy. Selective serotonin reuptake inhibitors (SSRIs) are sometimes used. Antidepressants usually take four to eight weeks to work. NIMH: Seasonal Affective Disorder
One medication is FDA-approved specifically for prevention. Extended-release bupropion is indicated for preventing seasonal major depressive episodes in people diagnosed with SAD. DailyMed: Wellbutrin XL prescribing information A Cochrane review found it lowers the chance of a winter episode returning, but it also brings more headaches, insomnia, and nausea than placebo. The reviewers advised clinicians to discuss the advantages and disadvantages with each patient. Cochrane Database of Systematic Reviews: Antidepressants for preventing SAD
All medications can have side effects. Talk with a health care provider before starting or stopping any medication. NIMH: Seasonal Affective Disorder
Vitamin D
The evidence is mixed. Many people with winter-pattern SAD have low vitamin D, so supplements may help, but studies have disagreed. Some found vitamin D as effective as light therapy, and others found no effect. Vitamin D can also interact with some medications. NIMH: Seasonal Affective Disorder Ask a provider before taking it, since some vitamins, including vitamin D, may be toxic in excessive doses. NCCIH: Seasonal Affective Disorder
Do daily habits help?
They can. Time outside, sitting near a window during the day, regular exercise, enough sleep, and staying connected with other people can all help. American Psychiatric Association: Seasonal Affective Disorder (SAD)
Avoid alcohol and illegal drugs, which can make depression worse. MedlinePlus: Seasonal affective disorder When drinking or drug use has become a way to get through a hard season, dual diagnosis treatment addresses both concerns together.
Can seasonal affective disorder be prevented?
Possibly, but the research is limited. Because SAD is so predictable, people with a history of it might benefit from starting treatment before their difficult season begins. NIMH notes that few studies have tested whether SAD can be prevented. NIMH: Seasonal Affective Disorder A Cochrane review of light therapy for prevention found only one small study and could not draw conclusions. Cochrane Database of Systematic Reviews: Light therapy for preventing SAD
If the same months are hard every year, raise it with a provider ahead of time.
When should you get help for seasonal depression?
Talk to a health care provider or mental health specialist if you notice symptoms of SAD in yourself or someone close to you. NIMH: Seasonal Affective Disorder There is no need to wait for the season to end. Symptoms usually get better on their own when the season changes, but they can improve more quickly with treatment, and SAD can sometimes become long-term depression. MedlinePlus: Seasonal affective disorder
Take thoughts of death or suicide seriously, in yourself or in someone else. Call or text 988 to reach the 988 Suicide and Crisis Lifeline, which offers support at any hour. SAMHSA: 988 Suicide and Crisis Lifeline If someone has attempted suicide, call 911 right away and do not leave the person alone. MedlinePlus: Seasonal affective disorder Family members can also read our overview of the warning signs for suicide.
Frequently asked questions
How long does seasonal affective disorder last?
Symptoms last about four to five months of the year. For winter-pattern SAD, they usually begin in late fall or early winter and ease in spring.
Is seasonal depression real depression?
Yes. In the DSM-5-TR, SAD is major depressive disorder with a seasonal pattern. It is diagnosed and treated as depression.
Can you have seasonal affective disorder in the summer?
Yes. Summer-pattern SAD is less common. It tends to bring trouble sleeping, poor appetite, restlessness, and anxiety instead of oversleeping and overeating.
Do light therapy lamps work for SAD?
Light therapy is a long-standing treatment for winter-pattern SAD. It is not right for everyone, so talk with a clinician first, especially if you have an eye condition or bipolar disorder.
Getting help at Ambrosia
Ambrosia provides depression treatment for adults at the Neuroscience Institute in West Palm Beach, with therapy in individual and group settings. Cognitive behavioral therapy is part of individual and group sessions across Ambrosia's programs.
If you already see a therapist and each winter still feels unmanageable, our guide on when weekly therapy isn't enough explains how more structured care works.