Is it just the winter blues or major depression? Does light therapy really work? Let’s unpack the most common questions about seasonal affective disorder (SAD).

There’s something about a cold, dark day in January that drags a good mood down. A cozy bed and Netflix look better than ever.

For up to 20% of Americans, shifting weather can cause seasonal depression symptoms.

Short, chilly days and dwindling sun bring on the so-called “winter blues” for many. But if fatigue and low mood triggered by changing seasons start to affect your daily functioning, it’s likely more serious.

Understanding what it means to have seasonal affective disorder can bring clarity.

Seasonal affective disorder is marked by significant changes to mood and behavior during certain times of the year.

It’s most common during the winter as the days shorten, sun fades, and temperatures drop. But some people do experience seasonal affective disorder in the spring and summer.

The symptoms of SAD are consistent with those of either major depressive disorder (MDD) or bipolar disorder, and they come and go with the seasons.

Q: Is SAD a real disorder?

A: The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) has actually nixed the term “seasonal affective disorder” in favor of major depressive disorder (MDD) “with seasonal pattern.”

All that means is that seasonal affective disorder is no longer considered to be a separate condition, but rather a specifier of major depression.

Bipolar disorder II can also be characterized by seasonality, with depressive episodes prominent in the fall and winter and manic episodes in the spring and summer.

Because the older term “seasonal affective disorder” is better known, we use it throughout this article.

Q: What is it that spurs SAD? The cold weather? Daylight savings?

A: Researchers continue to search for the most accurate answer to when does seasonal affective disorder start and why? But they know more now than ever before.

Though some studies suggest that low temperatures do in fact have an impact on mood and energy levels, scientists believe that lack of exposure to sunlight is the main reason why people get seasonal depression.

This would explain why the shorter, darker days of winter bring on the most severe depressive symptoms for the majority of folks with seasonal depression.

Sunlight helps the production of melatonin, the chemical in your body responsible for maintaining a normal circadian rhythm.

But when people with SAD aren’t exposed to enough light, their body produces too much melatonin, resulting in drowsiness, low moods, and other depressive symptoms.

Experts think that the combination of decreased sunlight in wintertime and a genetic predisposition for circadian rhythm irregularities leads to seasonal depression.

In addition, low levels and short durations of bright light can disrupt serotonin and vitamin D. Deficits of both are thought to be associated with depression.

Q: I noticed depression last winter. Do I have seasonal depression?

A: Experiencing depression for one season doesn’t necessarily mean you have SAD.

To be diagnosed with MDD with seasonal pattern, your depressive episodes must occur during one specific season for at least two consecutive years. And you have to experience a break from those symptoms during the other months.

For example, if your depression sets in at the beginning of fall and naturally subsides come springtime for two years in a row, you may be diagnosed with SAD.

In other words, one season of depressive episodes is insufficient for a SAD diagnosis.

Seasonal affective disorder symptoms

Q: Who gets seasonal affective disorder?

A: Though anyone can get SAD, it’s true that some people are more likely to experience it than others.

Women are significantly more likely than men to have seasonal depression, comprising around 75% of SAD diagnoses.

It’s still not totally clear as to why, but some scientists believe the prevalence of SAD in women is related to higher levels of cortisol and inflammation.

Young adults between the ages of 18 and 30 are also more likely to have SAD.

Other contributing factors to seasonal affective disorder

  • Your geographic region. Populations further from the equator have significantly higher rates of SAD. In the United States, for instance, 1% of people in Florida have seasonal depression compared to 9% in Alaska.
  • Other mental disorders. Along with major depression and bipolar disorder, seasonal affective disorder can co-occur with eating disorders, substance abuse, and attention deficit disorders.
  • Your type of work. Though there’s a lack of conclusive research, working jobs with night shifts can disrupt your circadian rhythm, making SAD more likely.
  • Family history. The chance of developing seasonal depression is higher if you have a family member with SAD, depression, schizophrenia, or other mental disorders.
  • Stress. Many people with SAD have negative feelings about winter and experience higher levels of stress during the fall and winter months.
  • Genetic predisposition. Having difficulty adjusting your circadian rhythm is likely genetic, increasing susceptibility to seasonal depression.

A note on genetic predispositions

Your genes play a role in whether you will develop some mental or physical health conditions, but they’re only one piece of the puzzle.

Epigenetics is the study of how the DNA you inherit does or does not manifest in you. This means that any genetic predispositions that run in your family can stay inactive or can even be reversible when signs show up early.

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Q: I’ve received a diagnosis of major depression. Does that mean I should expect seasonal depression every fall and winter?

A: Just because you have major depression doesn’t mean the fall and winter are bound to worsen your symptoms.

Between 10% and 20% of people diagnosed with MDD experience the seasonal changes in mood and behavior associated with SAD.

Additionally, around 10% of people with SAD actually experience summer-pattern depression, with symptoms peaking during the lighter-for-longer months.

Q: Is there a natural way to treat seasonal affective disorder?

A: There are lots of options for treating seasonal depression, including some natural remedies.

The approaches that many people have found the most success with are:

Medication management to treat seasonal affective disorder

Sometimes folks benefit best from medication, or a combination of meds and the above remedies plus routine changes.

Since SAD is associated with irregular serotonin levels, selective serotonin uptake inhibitor antidepressants (SSRIs) are commonly used to treat symptoms.

However, the antidepressant bupropion HCL (Wellbutrin) has been shown to be most effective and is currently the only medication approved by the FDA for treating SAD.

Some people experience mild or severe side effects from antidepressants. Always remember to speak with your doctor before starting or stopping medication.

The gloominess of fall and winter months can seriously mess with our circadian rhythms, disrupting sleep cycles, energy levels, and overall mood. So can the longer-lighter days of summer, for others.

Though seasonal depression symptoms can be overwhelming and debilitating, SAD is readily treatable with some changes to your exposure to light, participation in talk therapy, switching to a healthier and active lifestyle, and meds.

If you think you’re experiencing seasonal depression, you’re not alone. Millions of people live with seasonal affective disorder every year in the United States.

Consider reaching out to your doctor or mental health professional. You might want to ask about treatment options and find the one together that’s right for you.