Updated on September 29, 2025.
The cooler temperatures and shorter days of fall and winter may provide relief from summer heat and sun. But for some people, the seasonal shift can trigger changes in mood. These changes may take the form of seasonal affective disorder (SAD), a type of depression that develops during particular seasons and may resolve as the next season begins.
In most cases, SAD is more pronounced during these colder months, says Christina Leal-McKinley, MD, of Lakeview Regional Medical Center in Covington, Louisiana, but some people do experience SAD in the spring or summer. In the U.S., nearly half a million people experience symptoms of winter-related SAD each year. Another 10 to 20 percent of U.S. adults have less severe symptoms, sometimes called the winter blues.
While the exact cause of SAD is unknown, some people—including those who live in northern latitudes, those with a family history of SAD and those with depression or bipolar disorder—are at greater risk for SAD than others. Women are also more likely to have SAD than men.
Researchers have found that light has a lot to do with this condition: a lack of sunlight may interrupt the body’s biological clock that usually controls mood, sleep, and hormone levels.
People who develop SAD may also have an abnormal functioning of serotonin, a chemical in the brain that is responsible for controlling mood. They may also make too much of the sleep hormone melatonin, which can contribute to excessive sleepiness.
If left untreated, SAD can interfere with everyday life and increase the risk of other health concerns, like alcohol abuse.
Recognize the signs of SAD
A diagnosis of SAD is made if you have depression symptoms each season for two consecutive seasons. Symptoms of depression include:
- Feelings of depression all day, on more days than not
- Feelings of hopelessness
- Decreased energy levels
- Lack of interest in activities you once enjoyed
- Sleep problems
There are also some signs that describe SAD specifically. In the winter months, those with SAD can expect to have:
- Little energy
- Exhaustion
- A tendency to overeat and experience weight gain
- Cravings for carbohydrates
- Social withdrawal
Those with summertime SAD may notice:
- Weight loss or decreased appetite
- Sleeping problems
- Anxiety
- Irritability
- Restlessness
- Periods of violent behavior
How to ease symptoms of SAD
Symptoms usually improve as a new season begins, whether winter giving way to spring, or summer giving way to fall. But when you are at risk for SAD or have experienced symptoms in the past, it’s important to learn to identify and manage them so you can prepare for the changing seasons.
“Being cognizant of your seasonal shifts might help you become more aware of your mood fluctuations,” says Dr. McKinley. “We want to try to capture those changes when the season hits, so patients don’t suffer with the increased sleep issues, irritability and fatigue, which are all some of the downers that come with depression.”
One of the first things McKinley recommends you do is establish a regular sleep/wake cycle. “I usually assess my patients to see what their current daily schedule is and what behaviors need to be modified," she explains.
McKinley also suggests getting regular exercise and sticking with the same wakeup and bed time every day (even on the weekends). She also suggests fueling your body with whole, nutritious foods that will help keep your energy levels up throughout the day. And be sure to get plenty of natural light: eat lunch at a park instead of your desk, open your blinds and sit closer to bright windows.
Beyond building a healthy lifestyle and sleep routine, here are some of the most common SAD treatment options:
Medication: This is usually prescribed as the first line of treatment for SAD. Medications are very effective on their own, or may work in conjunction with other treatment methods. Certain antidepressants known as selective serotonin reuptake inhibitors (SSRIs)—such as fluoxetine, paroxetine and sertraline, among others—are typically used as the first drug of choice for SAD. It’s believed that they may help improve your brain’s serotonin levels, which can boost your mood. “We will prescribe these medications to try and augment the neurochemicals that manage our behaviors and our mood,” McKinley says. Your healthcare provider (HCP) may suggest that you take medication before the season begins and even after your symptoms have subsided to ensure they don’t return. It’s also possible that your HCP may try different medications to learn what works best for you and your symptoms.
Light therapy: This form of treatment has been around since the 1980s, and the main premise behind it is that increasing your exposure to bright, artificial light during the fall and winter months can ease the symptoms of winter-related SAD. The treatment typically involves sitting in front of a light box that emits 10,000 lux of cool-white fluorescent light for 20 to 60 minutes each morning through the fall and winter months. Thankfully, there’s no need to worry about skin-damaging ultraviolet rays as long as you get a light box that filters out UV rays.
Psychotherapy: Also known as talk therapy, psychotherapy can help with a wide assortment of mental and emotional health conditions like SAD, depression, anxiety, trauma or loss of a loved one. There are many different kinds of talk therapy. Cognitive behavioral therapy (CBT)is the method most commonly used for SAD. It involves working to change behavior and thought patterns so that you can learn to focus on and solve problems. CBT also helps you recognize negative thoughts and learn to replace them with positive ones and can help you cope with the symptoms of SAD, as well.
In addition to these treatments, vitamin D may also be considered as a treatment option. Although supplements have not been approved as an official SAD treatment, research shows that many people with SAD have lower levels of vitamin D. This could be from decreased exposure to sunlight or a diet low in vitamin D.
If you’re curious about your own vitamin D levels and are at risk for SAD, your doctor can order a simple blood test. If your levels are low, you may be advised to take a supplement or eat more vitamin D-rich foods such as salmon, whole milk, or Portobello mushrooms.
Whether you’ve experienced SAD in the past, you’re currently dealing with symptoms of SAD or you’re looking to manage certain lifestyle factors to lower your risk of SAD, McKinley says regular appointments with your HCP are extremely beneficial. “See your doctor sooner rather than later,” says McKinley. “It’s important to know that you’re not alone and help is always available.”
