Make it a Habit: Seasonal Affective Disorder and understanding the winter blues

When the days get shorter and the sun seems to disappear in the midafternoon, your good mood might disappear along with it. Are you just experiencing winter blahs, or is it something more serious?

Seasonal affective disorder, commonly known as SAD, is a real and clinically recognized form of depression that follows a seasonal pattern. Understanding what SAD is and what it isn’t can make a big difference in knowing when you might need help.

If you suspect that you or someone you know has SAD, consult a physician for a full assessment and treatment plan.

What exactly Is Seasonal Affective Disorder?

Seasonal affective disorder is a type of depression that typically appears during the fall and winter months, when daylight hours shrink. Symptoms typically begin between late September and early December, and the condition usually eases as spring arrives and the days start to get longer again.

Researchers believe SAD is linked to changes in light exposure. Sunlight plays a major role in regulating how the brain produces certain hormones and neurotransmitters, particularly melatonin, which helps regulate sleep, and serotonin, which supports mood and energy levels.

When you’re not getting as much natural light, these systems can fall out of balance. Your body’s internal clock — your circadian rhythm — also relies on sunlight to signal when to feel awake and when to wind down. Less daylight can disrupt this rhythm, leading to sluggishness, irritability and a general sense that something is off.

Common Symptoms: More than just feeling down

Although SAD shares symptoms with other forms of depression, its seasonal pattern is the key differentiator.

Symptoms can include a persistent low mood and a loss of interest in things that usually bring joy, such as hobbies, socializing or exercise. Work or school might feel overwhelming, with concentration especially difficult. Many people avoid social situations and prefer to hibernate at home. Fatigue is common, even after a full night’s sleep.

Unlike other forms of depression, SAD can also trigger cravings for carbohydrates such as bread, pasta and sweets.

Symptoms can range from mild to severe, and some individuals experience them so consistently each year that they can predict when the shift will begin.

Treatment options: What actually helps?

The good news is that SAD is highly treatable.

Start with small lifestyle changes. A morning walk, even on a cloudy day, provides some natural light to help reset your internal clock. Regular exercise, a consistent sleep schedule and staying socially connected even when it’s difficult, all support mood and energy levels.

Light therapy, or phototherapy, involves sitting in front of a 10,000-lux light box for about 20 to 30 minutes each morning. The light mimics natural outdoor light and helps reset the body’s internal clock. Light therapy is considered the first-line treatment for fall-winter SAD, and many people notice improvement within about two weeks. Regular lamps or sunlight through a window are not strong enough, so a medically approved device is key.

These approaches aren’t replacements for medical treatment if symptoms are significant, but they can support overall mood and energy.

Cognitive behavioral therapy for SAD, or CBT-SAD, helps identify and change negative thought patterns triggered by seasonal changes. Research shows CBT-SAD is as effective as light therapy and may produce longer-lasting benefits. Most people notice improvement after six to 12 sessions. A physician referral is typically required.

Some individuals benefit from antidepressants, especially SSRIs, which help regulate serotonin levels. A doctor may recommend starting medication before symptoms begin each year.

Because low vitamin D levels can contribute to mood issues — and sunlight helps the body produce vitamin D — some people with SAD see improvement with supplementation. However, vitamin D deficiency should be confirmed with physician-ordered testing before beginning supplements.

When it’s not really SAD: Conditions that get misidentified

It’s common for people to label any winter slump as SAD, but other conditions can mimic or overlap with it. Misidentifying the issue can delay proper treatment, so it helps to know what else might be happening. For some individuals, depression simply worsens in winter, but the underlying condition isn’t seasonal. True SAD follows a consistent annual pattern for at least two years.

Low energy, weight gain, fatigue and depressed mood can occur with thyroid dysfunction.

Because these winter symptoms can resemble thyroid problems, blood tests are needed to rule this out. Low iron levels can also cause fatigue, irritability and trouble concentrating — symptoms that overlap with SAD. Again, bloodwork can provide clarity.

Some people feel depressed in winter because of increased responsibilities, such as work deadlines, holiday stress and reduced downtime.

Understanding these distinctions is important because treatments differ widely. While light therapy might help someone with SAD, it won’t address thyroid issues or anemia. A proper evaluation is essential.

Why awareness matters

We often talk about mental health in broad terms, but seasonal affective disorder is a specific, diagnosable condition that can significantly affect daily life. And because it returns year after year, some people begin to dread certain seasons before they even arrive.

The more we understand SAD — its causes, symptoms, treatments and the conditions that resemble it — the better prepared we are to respond. No one needs to simply endure it. Help is available, and most people see meaningful improvement once they find the right combination of treatment and lifestyle changes.