Seasonal affective disorder (SAD) is a type of depression that comes and goes with the seasons, most often starting in late fall or early winter and lifting in spring. It is more than the “winter blues”: SAD can affect your sleep, energy, appetite and ability to get through the day. The good news is that it is very treatable with light therapy, talk therapy, medication or a combination.
If you notice the same heavy, low mood settling in around the same time every year, you are not imagining it, and you do not have to just wait it out. Here is what to know about the symptoms, causes and treatment of SAD.
What Is Seasonal Affective Disorder?
The National Institute of Mental Health (NIMH) describes SAD as a type of depression with a recurring seasonal pattern, with symptoms that last about 4 to 5 months each year. Cleveland Clinic explains that clinicians classify it as major depressive disorder with a seasonal pattern.
There are two main patterns:
- Winter-pattern SAD: Symptoms begin in the fall or winter and ease in spring and summer. This is the more common type.
- Summer-pattern SAD: Symptoms begin in the spring or summer. NIMH notes this form is less common.
SAD vs. the “Winter Blues”
Many people feel a little sluggish when days get shorter. SAD is different because it significantly affects how you function day to day. Cleveland Clinic estimates that about 5% of U.S. adults experience SAD, while roughly 10% to 20% have milder winter blues.
Symptoms of SAD
SAD shares many symptoms with other forms of depression. According to MedlinePlus, these can include sadness, hopelessness, irritability, loss of interest in activities, low energy, sleep problems, carbohydrate cravings, weight gain and thoughts of death or suicide.
Winter-Pattern Symptoms
NIMH lists symptoms that are more specific to winter-pattern SAD:
- Oversleeping (hypersomnia)
- Overeating, especially craving carbohydrates, which can lead to weight gain
- Social withdrawal
Summer-Pattern Symptoms
Summer-pattern SAD can look quite different. NIMH notes it may include:
- Trouble sleeping (insomnia)
- Poor appetite, leading to weight loss
- Restlessness and agitation
- Anxiety
- Episodes of aggressive behavior
The Mayo Clinic recommends seeing a health care provider if you feel down for days at a time, can’t get motivated to do things you normally enjoy, notice changes in your sleep or appetite, turn to alcohol or other substances for comfort, or feel hopeless or think about suicide.
What Causes SAD, and Who Is at Risk?
Researchers do not fully understand what causes SAD, but several factors appear to play a role. According to NIMH and Mayo Clinic, these include:
- Your body clock: Less sunlight in fall and winter can disrupt your circadian rhythm, the internal clock that helps regulate sleep and mood.
- Serotonin: People with SAD may have reduced activity of serotonin, a brain chemical that helps regulate mood.
- Melatonin: NIMH notes that people with winter-pattern SAD may produce too much melatonin, a hormone that makes you sleepy.
- Vitamin D: Less sunlight means the body makes less vitamin D, which may also affect serotonin activity.
Risk Factors
SAD is more common in some groups. NIMH says it occurs much more often in women than in men, usually begins in young adulthood and is more common in people who live farther north, where winter days are shorter. Cleveland Clinic adds that it often first appears between ages 18 and 30. Other risk factors include:
- A family history of depression
- Having major depression or bipolar disorder (NIMH notes SAD is more common in people with bipolar II disorder; learn more about bipolar I vs. bipolar II)
- Other conditions such as ADHD, eating disorders, anxiety disorders or panic disorder
Mayo Clinic warns that untreated SAD can lead to complications such as social withdrawal, school or work problems, substance misuse, anxiety, eating disorders and suicidal thoughts or behavior. If you find yourself drinking more during dark months, our guide on alcohol and depression explains why that can make symptoms worse.
How Seasonal Affective Disorder Is Diagnosed
There is no blood test or brain scan for SAD. Instead, a provider looks for a clear pattern. According to NIMH, a person must have symptoms of major depression, or the pattern-specific symptoms above, that occur during a specific season for at least two consecutive years. The seasonal episodes also have to be much more frequent than any depression the person has at other times of year.
Mayo Clinic’s SAD diagnosis and treatment guide says an evaluation may include a physical exam, lab tests such as a blood count or thyroid test, and a psychological evaluation. This helps rule out other conditions that can cause similar symptoms.
Treatment for SAD
Treatment can make a real difference, and many people use more than one approach.
Light Therapy
Light therapy is a first-line treatment for winter-pattern SAD. NIMH describes it as sitting in front of a very bright light box (10,000 lux) every day, usually first thing in the morning, from fall to spring. Mayo Clinic notes it often starts to help within a few days to a few weeks and causes few side effects.
Talk with your provider before buying a light box. Mayo Clinic cautions that this is especially important if you have bipolar disorder, because light therapy can trigger mania in some people.
Psychotherapy
Cognitive behavioral therapy (CBT) can be effective for SAD. NIMH describes a version adapted for SAD, called CBT-SAD, that helps people replace negative thoughts about the season with more helpful ones and plan enjoyable, engaging activities. Mayo Clinic adds that CBT can help reduce avoidance and build healthy habits like exercise.
Medication
Antidepressants may help, especially if symptoms are severe. NIMH notes that SSRIs are used to treat SAD and that the FDA has approved an extended-release form of bupropion to help prevent seasonal depressive episodes. Your provider will decide what is appropriate for you. Our guide to types of antidepressants explains how the main classes work.
Vitamin D and Daily Habits
NIMH reports mixed research results on vitamin D supplements for SAD, so talk with your provider before trying them. Mayo Clinic suggests getting more natural light, spending time outside even on cloudy days, exercising regularly and keeping a consistent sleep schedule.
When You Need More Support
If SAD is making it hard to work, parent or take care of yourself, a structured program such as intensive outpatient mental health treatment or a mental health partial hospitalization program can provide more help while you live at home. Some people also notice that seasonal low mood blends into year-round symptoms; our article on high-functioning depression covers lower-grade depression that lasts much longer.
Frequently Asked Questions
Is SAD a real form of depression?
Yes. SAD is a recognized form of depression that clinicians classify as major depressive disorder with a seasonal pattern.
Can you have SAD in the summer?
Yes. Summer-pattern SAD is less common, but it can cause insomnia, poor appetite, restlessness, anxiety and agitation during the warmer months.
How long does SAD last?
NIMH notes that symptoms typically last about 4 to 5 months per year and return around the same time each year without treatment.
What should I do if I’m having thoughts of suicide?
Get help right away. Call or text the 988 Suicide & Crisis Lifeline, which is free, confidential and available 24/7. If you or someone else is in immediate danger, call 911.
Get Help for Seasonal Affective Disorder in Lancaster, PA
You do not have to brace yourself for another hard winter alone. At The Ranch Pennsylvania Outpatient Services, our mental health treatment programs offer CBT, individual and group therapy, and psychiatric evaluation and medication management, with integrated care if substance use is also part of the picture. Visit our depression resource hub or learn more about depression treatment in Pennsylvania. You can also verify your insurance online. Our admissions team is available 24/7, and calls are free and confidential.
