Peoria Standard

As daylight saving time ends on November 2, many people may notice changes in their mood and energy levels. This shift is linked to seasonal affective disorder (SAD), a type of depression that occurs at certain times of the year.

“Seasonal affective disorder is also known as seasonal depression. It's a form of depression that occurs during different seasons,” said Erin Wojewodzki, APRN, a nurse practitioner with OSF HealthCare. “There's winter onset seasonal affective disorder, which typically begins during the fall months. And then there's a summer depression, where symptoms develop during spring and summer.”

In the United States, about 5% of adults are affected by SAD. The condition is most often diagnosed between ages 18 and 30 and is more common among women. People with a family history of mental health issues or those living in northern states such as Alaska, Vermont, and New Hampshire—where there are fewer hours of sunlight—are at higher risk.

Symptoms associated with SAD can range from mild anxiety to more severe problems that may require medical intervention.

“The symptoms of the winter onset SAD include symptoms such as depression, feelings of guilt, and a lack of desire to do those things that you typically love doing,” Wojewodzki explained. “There's a carbohydrate craving, it can impact sleep, and there can be feelings of suicidal ideation or thoughts.”

While the exact cause remains unclear, experts believe reduced sunlight plays a major role in triggering SAD. “We have this biological clock within us that's used to so much sunlight in the wintertime – that changes,” said Wojewodzki. “It gets darker earlier, and that can impact our mood, our sleep, our hormones, and lead to some of these symptoms.”

A lack of sunlight can also result in vitamin D deficiency. Vitamin D helps increase serotonin levels—a hormone important for mood regulation—and low serotonin has been linked to depression. Additionally, less sunlight affects melatonin production, which can make people feel more tired or groggy.

Diagnosing SAD does not involve blood tests or scans; instead health care providers assess symptoms and family history. They may use tools like the PHQ-9 questionnaire to determine levels of depression.

“We look at things like, are you having symptoms of depression?” Wojewodzki said. “Are those symptoms of depression occurring during a specific time of the year, every year, and have those symptoms occurred two or more times during a specific season where you've experienced these feelings?”

Treatment plans are individualized but might include light therapy to boost serotonin levels or recommendations for spending more time outdoors. Providers may suggest vitamin D supplements or prescribe antidepressant medications such as selective serotonin reuptake inhibitors (SSRIs). Social support is also encouraged.

“If you are feeling symptoms of depression, isolation, sleep issues, gaining weight, not yourself, and especially feeling like harming yourself, I want you to reach out to your health care provider,” Wojewodzki urged. “We can discuss different options to you, whether that's medication or non-medication options to help you through this hard time.”

For additional information about SAD or behavioral health concerns visit the OSF HealthCare website.