Winter isn't the only season that can bring out some serious blues.

When you hear the term “seasonal affective disorder,” odds are you think of wintertime blues.

“We tend to associate shorter days, less sunlight and cold weather with higher chances of depressed mood,” therapist Natalie Moore told HuffPost. “Conversely, when we think of summertime, we imagine longer days, sunshine and picture people being more joyful and optimistic.”

For some people, however, the sunnier seasons bring an emotional struggle. This lesser-known ― and often overlooked ― condition is called “reverse SAD” or summer-pattern SAD.

What is reverse SAD?

“Reverse seasonal affective disorder, or summer-pattern SAD, is a type of depression that occurs during the spring and summer months, as opposed to the more common winter-pattern SAD,” said board-certified psychiatrist and “Practical Optimism” author Dr. Sue Varma. “While most people associate SAD with the colder, darker months, some individuals experience a worsening of mood when the days get longer and brighter.”

A number of different factors can cause reverse SAD.

“Reverse SAD is thought to affect individuals who are particularly sensitive to circadian rhythm changes,” Moore said. “Physiological factors include discomfort from increased heat and humidity and sleep disruption caused by early sunrise.”

Changes in light exposure can throw off mood-regulating hormones like serotonin and melatonin in the summer, just as in the winter.

“Psychological factors include internal pressure to be happy during this time of year,” Moore said.

Summer comes with expectations to be outdoors, attend barbecues, take vacations, and generally be ‘on.’Erin Pash, licensed marriage and family therapist

The summer can be particularly tough for introverts, since social conventions call for increased participation in potentially energy-depleting activities in the summer.

“Other triggers may include summer stressors like vacation costs, childcare pressures, or problems with body image that are enhanced by our summer wardrobes,” said Dr. Samar McCutcheon, a psychiatrist with The Ohio State University Wexner Medical Center.

Summer tends to disrupt routines, which is especially challenging for........

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