Seasonal depression (SAD): symptoms, causes and treatment
CareOps editorial team · · 9 min read
Mental wellness information and service guidance published by CareOps.
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Read our full editorial standards →As the days get shorter, getting up in the morning becomes unusually hard. You sleep more but don't feel rested, you keep craving sweets and bread, and even plans with friends feel like too much. Then spring comes and your body feels light again, as if nothing happened. If this pattern repeats every year, it may be more than the winter blues: it may be seasonal depression. Here is what it means, what the symptoms look like, what may cause it and how to get through this winter more gently.
At a glance
- Seasonal affective disorder (SAD) is depression that comes back in the same season each year. In most cases it starts in late fall or early winter and goes away in spring and summer, lasting about four to five months.
- Winter-pattern SAD often adds oversleeping, carbohydrate cravings with weight gain, and pulling away from people to low mood. Researchers think it is linked to shorter daylight disrupting the body clock, serotonin and melatonin.
- Treatment centers on morning light therapy and CBT adapted for SAD. In daily life, morning daylight, a regular sleep schedule and planned activities help. If it is affecting daily life, see a doctor.
What is seasonal depression?
Seasonal affective disorder (SAD) is depression with a recurring seasonal pattern. According to the U.S. National Institute of Mental Health (NIMH), symptoms most often start in late fall or early winter and go away in spring and summer; this is called winter-pattern SAD or winter depression. A summer pattern, with depression in spring and summer, also exists but is less common. When people talk about fall or winter depression, they usually mean the winter pattern.
For a diagnosis, clinicians look at whether depressive episodes in a particular season have occurred for at least two consecutive years and whether depression in that season is more frequent than at other times of year. Not everyone with SAD has symptoms every single year, though. It most often begins in young adulthood, is much more common in women, and is more common in places farther north, where winter days are shorter.
Seasonal depression symptoms: winter and summer patterns
SAD includes the general symptoms of depression: a low, anxious or empty mood most of the day, nearly every day, for at least two weeks; loss of interest in things you used to enjoy; fatigue and low energy; trouble concentrating; guilt or worthlessness; and changes in sleep and appetite. Winter-pattern SAD can add the following.
- Oversleeping: you sleep for a long time but don't feel rested, and getting up is very hard.
- Carbohydrate cravings: you keep reaching for bread, noodles and sweets, and gain weight.
- Pulling away from people: you feel like “hibernating” and cut back on plans and contact.
The summer pattern can look the opposite: trouble sleeping, poor appetite with weight loss, and more restlessness and anxiety. Not everyone has every symptom. If low periods have alternated with times you felt elevated despite barely sleeping, also read bipolar disorder symptoms. NIMH notes that SAD is more common in people with bipolar disorder, especially bipolar II. If you sleep more and stay sleepy during the day regardless of season, see oversleeping: causes and what helps.
How is it different from the winter blues?
Many people feel a bit down as the days get shorter and feel better in spring. That is often called the winter blues. SAD is when the change runs deeper and affects how you feel, think and act, and disrupts daily life. Below is a rough guide; a diagnosis is made in a clinical visit.
| Winter blues | Seasonal depression | |
|---|---|---|
| Mood | Down or wistful at times | Low mood nearly every day |
| Daily life | You can manage as usual | Work, study and relationships suffer |
| Body | Little change | More sleep, changes in appetite and weight |
| Pattern | Varies from year to year | Returns in the same season each year |
It is also different from feeling stressed and worn out as the year-end gets busy. NIMH explains that SAD is tied to changes in daylight hours, not to events on the calendar. If changes in mood last more than two weeks regardless of season, also check early signs of depression.
What causes seasonal depression?
The causes are still being studied. So far, researchers think several things in the body shift together as daylight shortens.
- Serotonin: a brain chemical that helps regulate mood. Sunlight seems to help maintain serotonin, and shorter days may weaken this, lowering serotonin activity in winter.
- Melatonin: a hormone that keeps the sleep–wake rhythm. People with winter-pattern SAD may produce too much melatonin, which can lead to sleepiness and oversleeping.
- Body clock: as serotonin and melatonin shift, the daily rhythm may fail to adjust to shorter days, disrupting sleep, mood and behavior.
- Vitamin D: less sunlight means less vitamin D, and some research suggests this may add to symptoms.
Thoughts about the season, such as “Here comes another long winter” or “I can't do anything in winter,” are also common in people with SAD. It is not yet clear whether these thoughts are a cause or an effect, but they are an important part that can be worked on in treatment.
Seasonal depression treatment: light therapy and CBT
NIMH groups SAD treatments into four categories, light therapy, psychotherapy, medication and vitamin D, which can be used alone or together. Which treatment fits you is decided with your doctor.
- Light therapy: a mainstay of winter-pattern SAD treatment since the 1980s. You sit in front of a 10,000-lux light box, about 20 times brighter than indoor lighting, for about 30–45 minutes each morning, usually from fall to spring. A meta-analysis of randomized controlled trials (Golden et al., 2005) found that bright light treatment clearly reduced SAD symptoms, with effect sizes similar to those in most antidepressant trials. If you have an eye condition or take medication that increases sensitivity to light, talk with your doctor first.
- CBT adapted for SAD (CBT-SAD): twice-weekly sessions over six weeks that examine and change negative thoughts about winter and use behavioral activation to plan enjoyable activities. In a study that followed 177 adults over two winters (Rohan et al., 2016), there was no difference from light therapy in the first winter, but by the second winter fewer people in the CBT group had a recurrence (27.3%) than in the light therapy group (45.6%).
- Medication: as with other forms of depression, antidepressants may be used. Whether you need medication, and which one and when to start, is decided with your doctor.
Because SAD tends to start at a predictable time, people with a history of it may benefit from starting treatment before symptoms begin, around early fall. Few studies have looked at prevention directly, though, so it is best to decide what to start and when together with your doctor. For an overview of depression treatment and how to prepare for a first visit, see how depression is treated.
Coping with seasonal depression: five things for this winter
- Get morning daylight: go outside for a walk or sit by a window early after waking. Even an overcast day outdoors is brighter than indoors.
- Keep a steady wake-up time: wake at about the same time, weekends included. Even if you're sleeping more, getting up at a set time and seeing light helps more than staying in bed.
- Plan small activities ahead: instead of waiting to feel better, write one small thing per day on your calendar, such as a walk, a short call with a friend or cooking something you like. Changing the order this way is called behavioral activation.
- Move your body: walking or light exercise during the day gives you outdoor light and activity at the same time.
- Examine your thoughts about winter: when a thought like “Winter ruins everything” comes up, write down whether it is true and what you can still do in winter.
If heavy, unmotivated days go on for a long time, also read low energy and motivation. Many people look for supplements for seasonal depression, but NIMH notes that studies of vitamin D supplements for SAD have produced mixed results. Vitamin D can interact with some medications, so talk with your doctor before taking supplements.
How has your mood been lately? A depression self-check
The CareOps PHQ-9 depression check is not a test for seasonal depression specifically. It is a nine-item check on depression symptoms over the past two weeks. Taking it each fall and winter and keeping a record can help you see whether the pattern repeats. You can take it right away, with no login.
Try a self-assessment without signing inDepression screen (PHQ-9)Recent mood, interest and daily changes. Answer the app’s questionnaire and see your result right away.Start the check →When to see a doctor or professional
If low mood lasts nearly every day for more than two weeks, if work, study or relationships are suffering, or if changes in sleep and appetite are making life hard, don't wait for winter to pass. Talk with a mental health professional. If you have thoughts of wanting to disappear, don't carry them alone; reach out to a crisis line where you live.
If you need someone to talk to through the long winter
Seasonal depression returns at the same time each year, so the earlier you prepare, the easier it can be to get through. CareOps Maeumi is an AI counseling app that runs sessions with approaches such as cognitive behavioral therapy (CBT) and behavioral activation, helps you examine thoughts about winter and plan small activities, and remembers past sessions so the next one picks up where you left off. Get the app
Frequently asked questions
- What does seasonal depression mean?
- It is depression that returns in the same season each year. Most cases are the winter pattern, starting in late fall or early winter and going away in spring and summer, lasting about four to five months. A diagnosis looks at whether depression in that season has occurred for at least two consecutive years.
- Are fall depression and winter depression different?
- They usually refer to the same winter-pattern SAD. Symptoms often begin in late fall as the days shorten and feel worst in winter, so people call it either name. A separate summer pattern, with depression in spring and summer, is less common.
- How can I cope with seasonal depression?
- Getting morning daylight, keeping a steady wake-up time, planning small activities ahead and moving during the day are things you can try. If symptoms are affecting daily life, talk with your doctor about treatments such as light therapy or CBT.
- Can I use a light box at home?
- Light therapy is usually done at home each morning. Brightness, timing and when to start matter, though, and people with eye conditions or who take medication that increases light sensitivity may need medical supervision. It is best to talk with your doctor before starting.
- Do supplements help seasonal depression?
- NIMH notes that studies testing vitamin D supplements as a treatment for SAD have produced mixed results. Vitamin D can interact with some medications, so talk with your doctor before taking supplements. Morning light, a regular routine and treatment when needed come first.
Sources
- National Institute of Mental Health (NIMH), Seasonal Affective Disorder (checked 2026-10-28)
- Golden et al. (2005), The Efficacy of Light Therapy in the Treatment of Mood Disorders: A Review and Meta-Analysis of the Evidence, American Journal of Psychiatry
- Rohan et al. (2016), Outcomes One and Two Winters Following Cognitive-Behavioral Therapy or Light Therapy for Seasonal Affective Disorder, American Journal of Psychiatry
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