Understanding Seasonal Affective Disorder: Signs & Symptoms Of SAD

Medically reviewed by April Justice, LICSW

Updated May 10th, 2025 by BetterHelp Editorial Team

Do you have notable changes in mood during certain times of year—especially winter? If so, you’re not alone. According to the American Psychiatric Association, approximately 5% of people in the United States experience seasonal affective disorder (SAD). More than just sadness in winter, SAD is a serious mood disorder that can produce a variety of concerning symptoms. People with SAD may experience low mood, lack of energy, weight gain, and loss of interest in activities once enjoyed. Despite these challenges, it’s often possible to manage SAD symptoms with the right support. Below, we’ll take a look at seasonal affective disorder, its key symptoms, and how it can be treated.

You can manage seasonal depression with the right support

Address SAD with a licensed therapist

An overview of seasonal affective disorder (SAD)

For many people, the variations in weather and sun exposure that often accompany seasonal changes can have an impact on their mood. However, if you feel persistently sad and tired as fall and winter approach—or the spring and summer months, in rarer cases—it might be more than just the winter blues. You might be experiencing symptoms of seasonal depression (SAD)—sometimes called winter depression or summer SAD—which is a diagnosable mental illness in the category of depressive disorders.

Unlike other forms of clinical depression, seasonal affective disorder (SAD) doesn’t last throughout the year. Instead, mental health symptoms typically arise during certain seasons—usually the fall and winter months when there’s less daylight, so lower light levels and colder weather are common.

It can be easy to miss a diagnosis of SAD because those living with the condition may not have symptoms for most of the year. If you’ve noticed yourself having symptoms, it’s generally recommended that you meet with a mental health specialist for SAD evaluation and treatment advice.

Differences between SAD (seasonal affective disorder) and major depression

What can be confusing about seasonal affective disorder (SAD), or “winter depression”/”summer depression”, is that it’s considered a form of major depressive disorder (MDD). The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) lists seasonal affective disorder as “major depressive disorder with seasonal pattern.” The primary difference between SAD and major depression is that SAD begins and stops at specific times of year, while symptoms of major depression without seasonal patterns tend to persist year-round. The symptoms of these depressive episodes themselves, however, are typically the same or similar.

Another common difference between having SAD and major depression disorder is the way in which emotional symptoms tend to arise. People who have seasonal depression may feel more sad rather than irritable or angry, in contrast to the way many people experience the onset of major depression. There can also be differences in physical symptoms. For instance, an individual with SAD may start sleeping significantly longer than normal and develop an increased appetite rather than having insomnia and a decrease in appetite.

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Recognizing symptoms of SAD

Understanding the symptoms associated with each type of depression can help you to find worthwhile care and advice. The core DSM criteria for a diagnosis of major depressive disorder with seasonal pattern are as follows: “Depression that begins and ends during a specific season every year (with full remittance during other seasons) for at least two years and having more seasons of depression than seasons without depression over a lifetime.”

Symptoms of seasonal affective disorder (SAD)

The National Institute of Mental Health lists the following symptoms of seasonal affective disorder (SAD):

Lack of energy
Disrupted sleep patterns, like trouble sleeping or excessive sleepiness
More carbohydrate cravings than normal
Poor appetite or significantly increased appetite
Significant weight gain or weight loss
Withdrawing socially
Feelings of irritation or agitation
Negative feelings about the self
Restlessness
Anxiety
Suicidal ideation

If you or someone you know is struggling or in crisis, help is available. Text or call 988 or chat 988lifeline.org. Support is available 24/7. If you are experiencing trauma, support is available.

What causes someone to have SAD?

Researchers are still not sure why exactly some people develop seasonal affective disorder (SAD) and others don’t, but various theories are currently being studied. For one, disruptions in an individual’s circadian rhythm or body clock—which often occur with changes in light exposure—are thought to play a role. These disruptions may be partly due to alterations in melatonin levels, which can make you feel listless and tired.

There is also evidence that specific populations of people tend to be more at risk for having SAD than others. For instance, some research suggests that women may be four times more likely to have SAD than men, and younger adults are also thought to be more likely to develop the condition than older adults. People who work evening or night shifts are typically considered to be at a greater risk for having seasonal depression as well. Also, for people living with bipolar disorder, symptoms may be linked to a specific season. For example they may experience more depressive symptoms in the winter months.

Individuals who live further north or south of the equator—where climates tend to be colder and light tends to be less plentiful in the winter months—may be more prone to having symptoms of seasonal affective disorder, too. Findings from one study indicate that only 1% of Florida residents experience SAD compared to 9% of residents of New England and Alaska. Many experts also believe that people with a family history of having depression may be at greater risk for SAD. Those who have already been diagnosed with depression or bipolar disorder may experience worse SAD symptoms in the colder months as well.

Finally, as noted earlier, people with SAD may have low levels of vitamin D, which is another of the common risk factors. This is because vitamin D is connected to serotonin, a chemical in your brain that helps control mood. Research suggests that people who have seasonal depression may have increased levels of serotonin transporter, also called 5-HTT, which can reduce the amount of serotonin available for the brain to use. The causes of these increased levels are still being investigated but could be linked to genetics and environmental factors.

You can manage seasonal depression with the right support

Address SAD with a licensed therapist

Treatment for SAD

There are various research-supported treatment methods for when seasonal affective disorder (SAD) occurs. The right one for a given individual may depend on their symptom severity, when symptoms begin, and other elements of their mental health.

Light therapy for seasonal depression

If the dark days of winter tend to bring about symptoms of seasonal affective disorder (SAD) in an individual, exposure to light may have a positive effect on symptoms. Research suggests that having bright light therapy—in which participants expose themselves to artificial light or sunlight for prescribed periods—may effectively reduce symptoms of seasonal depression.

Light therapy dates back to the 1980s when SAD was first officially classified as a mental health condition. It typically involves using a box that emits strong light and is made specifically for the purpose of light therapy. The average lightbox produces 10,000 lux of cool-white fluorescent light and emits up to 20 times more light than regular indoor lighting. When the sun doesn’t shine as often in the fall and winter seasons, safely exposing oneself to this type of bright, artificial light may significantly improve SAD symptoms. It’s thought that this type of therapy may work by stabilizing an individual’s circadian rhythm and/or increasing serotonin levels.

A common light therapy treatment regimen consists of sitting in front of a lightbox first thing in the morning for 30 minutes. If you’re experiencing seasonal affective disorder, a healthcare professional can help you develop a treatment plan that may include light therapy. Be sure to consult with a licensed professional before starting light therapy, and take care to only use a lightbox intended for light therapy and according to the included directions.

Vitamin D supplements

Research suggests a correlation between low levels of vitamin D and having symptoms of seasonal affective disorder (SAD). Vitamin D—which is important for immune health and other vital functions—may be difficult to obtain in the winter months in the absence of sun. For this reason, vitamin D supplements are often incorporated into treatment plans for SAD.

Medication for SAD

Certain antidepressants, such as selective serotonin reuptake inhibitors (SSRIs), may also help decrease symptoms of seasonal affective disorder (SAD)—particularly when used in combination with psychotherapy. Many providers will prescribe light therapy first and medication and talk therapy later if it doesn’t work.

Antidepressant medications generally work by balancing serotonin levels, which are often deficient in people with depressive disorders. Always consult with a healthcare provider before starting, stopping, or changing any medication.

Psychotherapy for SAD

Many people who live with seasonal affective disorder (SAD) experience improvement after engaging in psychotherapy, or talk therapy. One common type of psychotherapy for SAD is cognitive behavioral therapy (CBT). A therapist may use CBT to help you identify distorted, negative thoughts and replace them with more positive, realistic ones. This technique may be used in conjunction with another therapeutic technique called behavioral activation.

For example, your therapist might help you reframe negative thoughts about cold weather that may be causing or contributing to sadness or a lack of energy. Then, they may guide you through a behavioral activation component. It might help you identify activities that you can enjoy inside or outside to help you cope with the winter weather, for instance, or positive sleep hygiene practices like going to sleep and waking at about the same times each day to improve the quality of your rest.

Therapy options for “winter season depression”

Research suggests that cognitive behavioral therapy (CBT) may be the most effective form of treatment for seasonal affective disorder (SAD) for many, but attending in-person sessions isn’t always an option. Some people might not have mental health care providers in their area, while others may struggle to travel to and from in-office appointments because of their symptoms. Online therapy can be a more convenient alternative in these kinds of situations.

Online therapy for depressive episodes during specific season

With an online therapy platform like BetterHelp, you can talk to a licensed therapist from home via video call, voice call, or in-app messaging. Research suggests that virtual talk therapy can be an effective way to address a variety of depressive symptoms. In one wide-ranging review, researchers indicated that online therapy may be effective and more affordable than in-person treatment for addressing symptoms of depression and other mental health conditions.

Takeaway

Seasonal affective disorder (SAD) is a form of depression that can seriously impact an individual’s emotional health and ability to function. Symptoms typically come on only during the late fall/winter months or late spring/summer months and resolve when the seasons change again. If symptoms are persistent, it may be more than the “winter blues.” If you’ve been wondering if you have SAD, know that treatment is available. Light therapy using a light box, medication, and cognitive behavioral therapy are the most common treatment options. It’s typically suggested that you meet with a mental health professional for treatment advice if you’ve noticed signs of a mental illness in yourself.

Frequently asked questions

Read more below for answers to questions commonly asked about this topic.

What are the signs you may be suffering from seasonal affective disorder?

Signs that a person is experiencing seasonal affective disorder may include persistent "low mood" almost every day for at least two weeks, pessimism, irritability, worthlessness, and fatigue. Other symptoms are changes in sleep patterns, weight changes, and suicidal thoughts. Additionally, individuals may experience difficulty concentrating, low energy, and social withdrawal, which are common seasonal affective disorder symptoms. These symptoms usually begin in late fall or early winter. However, for some people, symptoms start in the spring and summer months.

What are three symptoms of SAD?

A person experiencing SAD may feel persistent sadness almost every day for at least two weeks, hopelessness, and a loss of interest in activities that they once enjoyed. Other depression symptoms include difficulty concentrating, low energy, social withdrawal, and feeling sad frequently during specific seasons.

Can seasonal affective disorder be self-diagnosed?

Proper diagnosis of seasonal affective disorder (SAD) requires the expertise of a mental health professional. For an accurate diagnosis, the client's symptoms must meet the criteria in the DSM-5. Your therapist will conduct the needed assessments and screenings and rule out the possibility of physical conditions that may contribute to the condition. If you think you are experiencing symptoms of SAD, it's essential to seek a diagnosis to receive the most accurate treatment.

If you think you’re experiencing symptoms of SAD, it’s important to seek a professional diagnosis for proper treatment. SAD occurs during certain seasons (early winter, early summer), and noticing when symptoms start can help with diagnosis, especially between seasonal changes.

Can seasonal affective disorder be a mild form of depression?

DSM-5 classifies seasonal affective disorder as a form of depression related to changes in seasons. While some people only have mild symptoms, others experience seasonal depressive episodes that disrupt sleep, energy levels, and routines. As with other types of depression, SAD may get worse if not properly addressed. Summer depression is a less frequent but recognized form of this common disorder.

What can seasonal affective disorder look like on a person?

Manifestations of SAD symptoms can vary from person to person, depending on the severity. A person with SAD may feel a persistent low mood, loss of interest in things once enjoyed, a feeling of worthlessness, trouble sleeping or oversleeping, weight loss or gain, reduced social interactions, in some cases, may experience eating disorders. Symptoms commonly first appear during adolescence or young adulthood, affecting a person’s ability to keep functioning properly during daily tasks.

If you or someone you know is struggling, support is available through the Suicide and Crisis Lifeline by texting or calling 988.

Are there cures for seasonal affective disorder?

A range of treatments can help a person with seasonal affective disorder. They may include exposure to sunlight, light therapy, certain types of therapy called talk therapy, and antidepressant medications. Other treatment options may involve dietary supplements, such as vitamin D, which may help improve symptoms in some individuals. Alternative treatments, like exercise or mindfulness, also help prevent SAD.

What are the five signs of emotional suffering?

Signs that a person may be undergoing emotional suffering include mood changes, withdrawal from other people, problems controlling anger, neglecting self-care, and suffering from hopelessness. These signs can appear in people with conditions like bipolar I disorder, bipolar II disorder, or eating disorders, where emotions affect daily functioning and relationships.

What are the three Ps of depression?

The three P's of depression are pervasiveness, permanence, and personalization. These three unhelpful forms of looking at things can contribute to feelings of depression.

What's the seasonal affective disorder hormone called?

Melatonin and serotonin are brain chemicals associated with seasonal affective disorder. Shorter daylight hours and less sunlight can reduce serotonin activity. Reduction of serotonin may cause depression. Melatonin is a hormone that can make a person sleepy. Individuals experiencing SAD have too much melatonin. Melatonin is a hormone that helps regulate sleep, and people experiencing SAD often produce more melatonin than usual, making them feel overly sleepy. Exposure to very bright light can help balance these brain chemicals and improve mood.

Can vitamin D help with seasonal affective disorder?

Seasonal affective disorder (SAD) is associated with vitamin D deficiency. However, research indicates that vitamin D supplementation for seasonal affective disorder shows inconsistent results. Maintaining healthy vitamin D levels may help prevent symptoms, while boosting serotonin activity through sunlight or therapy can also support mood regulation.

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