As daylight shortens in the fall, many people notice their mood shifts with it. Feeling flatter in November than in June is common, and it usually passes. For some, the change runs deeper and lasts longer — depression that arrives with the season and lifts when the season turns.
According to the National Institute of Mental Health, seasonal affective disorder (SAD) is a type of depression defined by a recurring seasonal pattern, with symptoms lasting roughly 4 to 5 months out of the year. That’s a substantial share of life to spend struggling — and it’s treatable.
If you or someone you know is in immediate danger, call 911 or go to the nearest emergency room. If you’re struggling or having thoughts of suicide, call or text the 988 Suicide & Crisis Lifeline at 988. The National Rehab Hotline at 866-210-1303 is for non-emergency information, support and referrals.
What Is Seasonal Affective Disorder?
SAD is not a separate illness from depression. It’s depression on a predictable seasonal rhythm. NIMH describes two patterns. Winter-pattern SAD, or winter depression, is the more common form: Symptoms begin in late fall and ease in spring. Summer-pattern SAD runs the opposite direction and is less common.
A diagnosis requires depressive episodes that occur during a specific season for at least 2 consecutive years and happen more often then than at other times of year. Not everyone with SAD has symptoms every year. It occurs much more often in women than men and usually begins in young adulthood.
Winter Blues, Holiday Stress or Something More?
The phrase “winter blues” describes something real but milder — a dip in energy and mood most people can work around. The dividing line is interference: How much are these changes affecting your ability to get through a normal day?
That matters, because depression is rarely mild once it takes hold. Per NCHS Data Brief 527, among adolescents and adults with depression, 87.9% reported at least some difficulty with work, home or social activities because of their symptoms.
SAD is also distinct from holiday stress. NIMH is explicit that the depression in SAD tracks daylight hours, not the calendar. Family gatherings, travel and year-end obligations are a different pressure, even though they land in the same months.
Signs of Seasonal Affective Disorder
Because SAD is a form of depression, the core symptoms are the same: a persistent low or empty mood most of the day, nearly every day, for at least 2 weeks; loss of interest in things you enjoy; fatigue; trouble concentrating; and guilt or worthlessness.
On top of those, NIMH describes symptoms specific to each pattern. Winter-pattern SAD often includes:
- Oversleeping
- Overeating, particularly carbohydrate cravings, leading to weight gain
- Social withdrawal — a feeling of wanting to hibernate
Summer-pattern SAD often includes:
- Trouble sleeping
- Poor appetite and weight loss
- Restlessness and agitation
- Anxiety
Depression of any kind can bring thoughts of death or suicide. If that’s happening for you or someone close to you, it’s not something to wait out until spring. Call or text 988. If you’re worried about someone else, our guide on how to help a loved one in a mental health crisis covers how to start that conversation.
Why Seasonal Depression Happens
Research points to daylight. NIMH reports that people with SAD, particularly the winter pattern, have reduced serotonin — the brain chemical that helps regulate mood — and that sunlight influences the molecules keeping it stable. Melatonin is involved too: People with winter-pattern SAD tend to produce too much, which contributes to oversleeping and daytime sluggishness. Low vitamin D may compound both.
Latitude matters as a result. NIMH notes SAD is more common farther north, where winter days are shortest — more likely in Alaska or New England than in Texas or Florida.
Seasonal Depression and Substance Use
Depression and substance use frequently travel together, and a season that reliably lowers mood is one that can quietly raise use. Drinking more through the winter or reaching for something to get to sleep can start as coping and become a problem of its own.
The overlap is well documented. Among the 46.3 million adults who had a substance use disorder in 2024, 45.8% also had a mental illness, according to the 2024 National Survey on Drug Use and Health. When both are present, dual diagnosis treatment addresses them together.
Untreated depression also makes recovery harder to hold onto. The fall and winter months are worth planning for in advance — more structure, more contact with people, a plan for the stretches when motivation drops. Our relapse prevention hotline page covers what that kind of plan can include.
Treatment and Support Options
SAD responds to treatment. NIMH groups the options into four categories that can be used alone or in combination:
- Light therapy has been a mainstay for winter-pattern SAD since the 1980s, using a bright light box during the darker months to make up for reduced sunlight. It’s not right for everyone — certain eye conditions and light-sensitizing medications can rule it out — so raise it with a provider first.
- Psychotherapy, specifically cognitive behavioral therapy adapted for SAD. Compared directly, CBT and light therapy improved symptoms about equally, and a study following people across two winters found the benefits of CBT lasted longer.
- Antidepressant medication. NIMH notes the FDA has approved an extended-release form of bupropion that can prevent seasonal depressive episodes from recurring when taken daily from fall through early spring.
- Vitamin D. Study results are mixed and it interacts with some medications, so discuss it with a provider rather than starting on your own.
Treatment for depression is common, not unusual. NCHS Data Brief 528 found that 11.4% of U.S. adults took prescription medication for depression in 2023 — 15.3% of women and 7.4% of men.
Because SAD arrives on a schedule, it can also be planned for. NIMH notes that people with a history of it may benefit from starting treatment before the season begins.
Where to Find Support
If you’re in crisis or having thoughts of suicide, call or text the 988 Suicide & Crisis Lifeline at 988, or chat at 988lifeline.org. In a life-threatening emergency, call 911. These lines are available around the clock and are the right first call when the situation is urgent.
If what you need is a starting point — help finding treatment near you, answers about cost or a next step for yourself or someone you care about — the National Rehab Hotline is available 24/7 at 866-210-1303. The call is free and confidential, connecting you with information, guidance and referrals to local resources. It’s a non-emergency line. Our mental health hotline page is another place to start.
Frequently Asked Questions
- Is Seasonal Affective Disorder a Real Diagnosis? Yes. NIMH describes SAD as depression with a recurrent seasonal pattern. To meet the criteria, depressive episodes must occur during a specific season for at least 2 consecutive years and happen more often then than at other times of year.
- What Is the Difference Between the Winter Blues and SAD? Severity and interference. Feeling lower in the darker months while still managing work and relationships is common. When those changes persist most of the day nearly every day for 2 weeks or more and start affecting your ability to function, talk with a health care provider.
- Can You Get Seasonal Affective Disorder in the Summer? Yes, though it’s less common. Summer-pattern SAD brings depressive symptoms in spring and summer, often with insomnia, poor appetite, weight loss and agitation rather than the oversleeping and carbohydrate cravings of the winter pattern.
- Does Seasonal Depression Make Substance Use Worse? It can. Alcohol and other substances are often used to manage low mood or sleep trouble, and that pattern can deepen across a season. The two co-occur frequently — 45.8% of adults with a substance use disorder in 2024 also had a mental illness.
- How Much Does It Cost to Call the National Rehab Hotline? Nothing. The line is free and confidential, available 24/7 at 866-210-1303. It’s a non-emergency line for information, guidance and referrals. For immediate danger call 911, and for a mental health crisis call or text 988.
- When Should I Start Treatment If I Get SAD Every Year? Because the timing is predictable, NIMH notes people with a history of SAD may benefit from starting treatment before the season does. Raising it with a provider in early fall leaves time to work out what to try.
Seasonal depression is often treated as something to endure until spring. It doesn’t have to be. If you’re in crisis, call or text 988. When you’re ready to look at treatment options, call the National Rehab Hotline at 866-210-1303 — free, confidential and available 24/7.
