An Overview of Seasonal Affective Depression

Seasonal Affective Disorder (SAD) is a form of recurrent major depressive disorder or bipolar disorder that follows a seasonal pattern, most commonly occurring during the fall and winter months when daylight exposure decreases. Less frequently, there are some individuals who experience SAD during spring or summer. This disorder can present in various way for different people and may require mental health support. 

In this blog post, we provide an overview of SAD, including symptoms, risk factors, treatments, and more.

Symptoms of SAD 

People with SAD often experience symptoms such as: 

• Low energy or fatigue  
• Feelings of guilt Feelings of sadness or hopelessness 
• Changes in sleep (oversleeping is common as well as insomnia) 
• Changes in appetite (especially craving carbohydrates) 
• Difficulty concentrating and becoming easily frustrated 
• Loss of interest in activities they usually enjoy Increased appetite, often craving carbohydrates 
• Weight gain 
• Social withdrawal (referred to as hibernating)

Summer-Onset SAD 

In summer-onset SAD (which is less common), symptoms may include insomnia, decreased appetite, anxiety, and agitation.

The Difference Between Wintertime Blues and SAD 

What’s the difference between “wintertime blues” and SAD? The level one is able to function. With winter blues, an individual will feel less energetic and wish to remain home; however, this does not affect their daily functioning. For example, an individual may not want to socialize as much for a few days but then find themselves looking forward to doing other activities, such as hobbies or a family gathering. There is still interest in activities, but the level of interest fluctuates.

Who is at Greater Risk for SAD? 

SAD is more prevalent in areas farther from the equator, where seasonal variation in daylight is greater. This type of depression typically begins in young adulthood and is four times more common in women than in men. A family history, existing diagnosis of depression, or mood disorder increases an individual's risks for SAD. About 5% of the population is affected and can benefit from professional mental health support.

Where Does SAD Come From?  

The exact cause is not fully understood by professionals. It’s thought to be related to reduced exposure to natural sunlight, which can disrupt the body’s internal clock and affect levels of serotonin and melatonin — both of which influence mood and sleep. Here are a few indicators that we know affect SAD: 

• Circadian rhythm disruption: Reduced daylight exposure in winter can shift the body’s internal clock, leading to mood and sleep disturbances. 
• Neurotransmitter changes: Decreased sunlight may lower serotonin activity, contributing to depressive symptoms. 
• Melatonin regulation: Longer nights and shorter days increase melatonin production, leading to fatigue and lethargy. 
• Vitamin D deficiency: Limited sunlight reduces vitamin D synthesis, which may also affect serotonin activity and mood regulation.

What Are Some SAD Treatments? 

Common treatments include light therapy (using a special light box), psychotherapy (especially cognitive-behavioral therapy), lifestyle adjustments (such as more outdoor activity and exercise), maintaining a schedule, and medication. Excellent self-care is recommended as a proactive approach to maintaining mental wellness year-round. 

Management of SAD can include the following: 

Light therapy (Phototherapy): First-line treatment. Exposure to bright artificial light (10,000 lux for ~20–30 minutes daily) simulates natural sunlight and helps regulate circadian rhythms. 

Psychotherapy: Cognitive Behavioral Therapy (CBT), especially CBT tailored for SAD, has strong evidence for effectiveness. 

Pharmacotherapy: Antidepressants (e.g., SSRIs such as sertraline or fluoxetine; bupropion XL is FDA-approved for SAD prevention). 

Lifestyle modifications: Adjustments to one’s lifestyle can significantly impact seasonal depression. 

• Increase outdoor activity and exercise. 
• Maintain a healthy, balanced diet. 
• Maximizing natural light exposure (e.g., sitting near windows, going for daytime walks). 
• Maintain good sleep hygiene. Keep structure within the day. 
• Create a plan for enjoyable activities, such as a hobby or interest. 
• Plan phone calls and interactions with friends and loved ones. 

Vitamin D supplementation: May be beneficial, especially in individuals with a deficiency. Please check with your physician before taking any supplements.

Visit the National Institute of Mental Health for a more in-depth look at SAD.

Where Can I Get Help for SAD?  

Here at Tar Heel Human Services, P.C., we have a team of therapists dedicated to client care and mental health support. If you are interested in speaking to a professional about depression or any other mental health challenges, contact us today. Our staff will match you with a therapist who best meets your specific needs. In many cases, North Carolina residents can choose between in-person appointments and teletherapy. Give us a call today or click below for our online contact form.

Written by Michelle Tanner, MSW, LCSW