Seasonal depression explained: Symptoms, treatment and prevention

Overview: Seasonal Affective Disorder (SAD) is a type of depression that follows a seasonal pattern, most commonly appearing during late fall and winter. Reduced sunlight, colder temperatures and holiday stress can trigger its symptoms. Discover signs, symptoms and treatment options for SAD. 

The onset of winter brings shorter days, colder weather and less sunlight, all of which can leave you feeling down or “blue” more often than in the summer months. And for some, this goes beyond the “winter blues” and becomes Seasonal Affective Disorder (SAD). SAD is a form of depression that occurs yearly, typically during late fall and winter, and affects about 5% of the population. 

So how do you know if you’re experiencing a case of the winter blues or if it’s something more, like SAD?: Let’s break down SAD: What it is, what causes it, how it compares to other types of depression and when to seek help.

What is Seasonal Affective Disorder and what causes it?

SAD is a major depressive disorder that occurs with a seasonal pattern, most often during the winter.

Reduced sunlight in the winter can lower serotonin and melatonin levels, affecting mood and sleep and contributing to seasonal depression. The cold weather and limited outdoor activities can heighten these feelings, as well as increase feelings of isolation.

On top of less sunlight and colder temperatures, winter can be a stressful time due to external pressures that come with the holidays. These factors can make symptoms of SAD more intense:

• Increased alcohol use: Alcohol is a depressant and can disrupt sleep.
• Social media pressure: Comparing yourself to others can increase stress.
• Relationship strain: Family conflicts or loneliness can amplify sadness.

Symptoms of SAD can include:

• Persistent sadness or hopelessness
• Loss of interest in activities
• Changes in appetite and sleep
• Low energy or fatigue
• Difficulty concentrating

Unlike the winter blues or holiday stress, SAD lasts for weeks or months and interferes with daily life. SAD symptoms will typically improve when the seasons change.

How can I cope with SAD?

• Light therapy, also known as phototherapy: Expose yourself to a specific type of light wavelength that mimics outdoor light to help regulate your mood.
• Exercise: Aim for daily movement, even short sessions, to decrease SAD symptoms.
• Social connection: Surround yourself with supportive people or join online groups to fend off feelings of isolation.
• Healthy habits: Eat a balanced diet, get adequate sleep and limit screen time.
• Talk to your health care provider if symptoms persist for two weeks or interfere with life. 

How does seasonal depression differ from other types of depression?

While seasonal depression shares many symptoms with other forms of depression, its timing and triggers set it apart.

Major depression: SAD’s seasonal pattern is a key distinction from major depressive disorder, which can occur at any time of year and often persists for weeks or months without a clear seasonal link. Major depression is influenced by a combination of factors such as genetics, stress and life events, making it less predictable than SAD.

Postpartum depression: Postpartum depression affects new mothers after childbirth. Unlike SAD, postpartum depression is driven by hormonal changes, sleep deprivation and the stress of caring for a newborn. Symptoms can include sadness, anxiety and difficulty bonding with the baby. 

Discover signs of postpartum depression

While the three types of depression share feelings of hopelessness and fatigue, their causes differ.

Can SAD be prevented?

Due to the seasonality and predictability of SAD, if you’ve experienced SAD symptoms in the past, you may benefit from starting treatment options and coping methods before the seasonal change. It’s helpful to discuss personalized treatment plans with a health care provider, so you know when and how to potentially prevent SAD symptoms.

Can you experience seasonal depression in the summer?

Although not as common, some people experience seasonal depression during the summer months. People with summer SAD often have symptoms such as anxiety, irritability, insomnia and appetite changes, leading to weight loss. The causes of summer SAD aren’t fully understood, but factors like heat, humidity and longer daylight hours that disrupt sleep patterns may play a role. 

When should I see a doctor about SAD?

You may experience some symptoms of depression around the holidays, and it might not mean that you meet the criteria for a SAD diagnosis. If you’re experiencing new or worsening symptoms that last at least two weeks and occur daily or nearly daily, you should connect with your primary care provider or a behavioral health professional.

If your symptoms interfere with your daily life (work, relationships, self-care) or you have thoughts about suicide, you should seek help from a behavioral health professional right away.

The National 988 Suicide and Crisis Lifeline is available 24/7.

This blog was medically reviewed by a MercyOne provider.