Why Do I Get Depressed in the Summer?

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Now that it's summer, it seems like all of my friends and family are out enjoying the beautiful weather and having a great time.  Yet, here I am once again feeling sad and blue and not really feeling like joining in on the fun.  Why do I get so depressed in the summer?  This seems to happen to me every year.  Is this just a coincidence or is there a biological reason behind my summer depression?

Dr. Harrison's Answer:

What is summertime sadness?

Seasonal Affective Disorder (SAD), currently known as Major Depressive Disorder With Seasonal Pattern in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), is a type of depression that is related to changes in seasons. For individuals with SAD, symptoms start about the same time each year. While the symptoms of SAD most commonly begin in the fall and last through the winter months, in about 10% of people with SAD, symptoms develop in spring and last through summer. Summer-onset Seasonal Affective Disorder is commonly known as summertime sadness or summertime depression.


The symptoms of Seasonal Affective Disorder overlap quite a bit with the symptoms of other depressive disorders and can include sadness, hopelessness, decreased energy, decreased memory and concentration, sleep changes, appetite changes and social isolation.

When SAD is severe, thoughts of suicide can develop, and if unaddressed, these thoughts can lead to suicide attempts. Unlike winter-onset SAD which is often associated with sad mood, sleeping too much and overeating, summer-onset SAD is more often associated with irritable mood, difficulty sleeping and loss of appetite.

Both types of SAD can be associated with isolation from social support and increased risk of developing substance abuse in an attempt to control symptoms (i.e. drinking more alcohol at night while trying to fall asleep).

How common is Summer-Onset Seasonal Affective Disorder

An estimated 500,000 people experience Seasonal Affective Disorder. One source cites that about 10% of those are known to have summer-onset. Putting those two statistics together, there is a possibility that around 50,000 people will experience summertime sadness that impairs their functioning enough to be called a disorder. Even more will experience summertime sadness, but may not develop functional impairment as a result.

What causes it?

Like all health conditions, Seasonal Affective Disorders caused by a combination of biological, psychological and social factors. Most often, people think of body image issues, a dislike of summer heat, financial pressures, and loss of routine. While all of these factors certainly contribute, they are in addition to underlying biological mechanisms that put some individuals at higher risk for developing summer depression.

The specific biological mechanisms that cause Seasonal Affective Disorder are not fully known, but evidence suggests that changes in circadian rhythms (due to sunlight changes), serotonin levels and melatonin levels contribute to seasonal depression. Females are disproportionately affected, which suggests there may be additional hormonal factors at play.

Finally, the environment plays a significant role. There are higher rates of SAD in cities that are further from the equator. As daylight sun gets shorter, winter-onset symptoms increase. However, the rate of summer-onset depression seems to be higher in cities that are closer to the equator. The exact reasons for this difference are unknown, but support that sunlight and other environmental cues play a critical role in quality of mood for many people.

How do I know if I have it?

Factors that increase risk of developing summer onset Seasonal Affective Disorder include:

  • Female

  • Family history of summer onset SAD

  • Live closer to the equator

  • Body image concerns

  • Multiple stressors

The biggest sign that someone may have Seasonal Affective Disorder is negative anticipation of a certain month of the year. Because symptoms typically appear the same time each year like clockwork, while seemingly everyone else is basking in the beauty of blossoming flowers and warm weather, individuals with summertime SAD are already beginning to feel the irritability, sleep and appetite changes.

The Seasonal Pattern Assessment Questionnaire (SPAQ) is a standardized tool that detects SAD. A score of 11 or greater strongly suggests a diagnosis of Seasonal Affective Disorder, while a score of 8-11 suggests a pattern of seasonal mood changes which may or may not be severe enough to qualify for a Seasonal Affective Disorder diagnosis.

What can I do about it?

Because many other illness such as Major Depression, Bipolar Disorder, Substance Use Disorders and Anxiety Disorders can mimic the symptoms of SAD, if you think you or someone you know may have summer depression, it is important to get a full evaluation by a therapist or psychiatrist. Additionally, many physical illnesses such as hypothyroidism, anemia and diabetes can mimic symptoms of depression, so a general physical is also a good idea.

If the diagnosis turns out to be summer onset Seasonal Affective Disorder, the good news is that it is very treatable.  While there does not appear to be evidence that light therapy is effective in treating the summer variety of SAD, there are other treatments, such as tryptophan, St. John’s Wort, cognitive behavioral therapy and antidepressants have been used successfully in individuals with this condition.

Finally, like all health conditions, the management of summertime sadness should include a well-rounded mental and physical fitness plan that includes adequate amounts of sleep, healthy eating, regular physical activity and minimization of stress.

Many people don’t realize that summertime depression is a “real” illness. Hopefully this article has demonstrated that summer onset Seasonal Affective Disorder is a health condition that, when recognized, can be successfully treated.


Blaszczak, Jessica.  "10 Things You Didn't Know About Seasonal Affective Disorder."  Psych Central.  Psych Central.  Reviewed by John M. Grohol, Psy.D.:  January 30, 2013.  Accessed:  July 29, 2015.

Griffin, R. Morgan.  "Tips for Summer Depression:  School’s out. It’s hot. And you’re not having any fun."  WebMD.  WebMD, LLC.  Reviewed by Joseph Goldberg, MD:  January 14, 2015.  Accessed:  July 29, 2015.

"Seasonal Depression."  Cleveland Clinic.  The Cleveland Clinic Foundation.  Reviewed:  November 12, 2013.  Accessed:  July 29, 2015.

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