Sad in the sunshine? You may have summer seasonal depression

Summer seasonal affective disorder is not as well-known as winter SAD, but it holds a higher risk for suicide and may become more prevalent with climate change, writes Richard Sima

The distinct environmental features of summer – heat, humidity and pollen – are believed to be the causes of summer depression (Getty)

Summer is a time of outdoor fun for many people, especially those who have slogged through winter’s bitter cold. Not so for individuals who suffer from summer depression.

Heat, humidity and pollen likely cause summer sadness, while reduced daylight causes winter seasonal affective disorder (SAD).

Compared with winter SAD, summer depression has not received as much attention, either in research or more general awareness.

“It certainly deserves more study, certainly deserves more concern,” said Norman Rosenthal, a psychiatrist at Georgetown University School of Medicine who first described SAD, in the scientific literature in 1984.

The symptoms of winter and summer SAD appear to be different. They both are marked by sad mood and reduced feelings of pleasure, but winter depression patients tend to oversleep, overeat and feel sluggish, Rosenthal said. “The summer ones were in many ways the opposite,” he said. “Less of an appetite, insomnia.”

Summer depression is also a more agitated depression, where patients tend to feel more distressed than lethargic as in winter depression.

Individuals with summer depression may be at an increased risk of suicide. Suicidal behaviour peaks in the late spring and early summer, but dips in the winter.

This may be because depression patients who feel suicidal during the winter may not have the energy to carry out the plan, said Rosenthal, whose upcoming book, Defeating SAD: A Guide to Health and Happiness Through All Seasons, aims to provide an up to date and concise understanding of SAD and practical strategies to counter it. People with summer depression who are both sad and agitated, however, unfortunately may have more energy to harm themselves.

Summer SAD is more heterogeneous and varied in nature, which has also made it more difficult for researchers to study. Compared with winter SAD, which affects about 5 per cent of Americans, there has not been as much research on summer seasonal affective disorder in the decades since Rosenthal and his colleagues first described it.

In one study of 2,819 Danish subjects, about 0.1 per cent met the criteria for summer SAD. Summer sadness, though seemingly rarer than winter depression, should be acknowledged and treated by medical professionals, experts said.

“Recognise it’s not all in your head,” said Kelly Rohan, professor of psychological science at the University of Vermont. “It is a real thing.”

The distinct environmental features of summer – heat, humidity and pollen – are believed to be the causes of summer depression.

In one of the original studies, Rosenthal and his colleagues surveyed people asking what they attributed their summer sadness to.

“They say constant heat, or I can’t stand the light,” Rosenthal said. “I’ve had people say that the light kind of cuts through me like a knife, I can’t stand it. And bright light actually can predispose to mania.”

These different factors may account for the mixed symptoms people with summer depression feel; the heat and humidity are unpleasant, while the light of the summer sun may be activating in a negative way.

Higher temperatures have also been linked with higher rates of suicide in the United States and Mexico, as well as an increased use of depressive words in social media posts.

Pollen counts are higher in the spring and summer and may also contribute to summer depression. One 2019 study of 1,306 Old Order Amish found that high pollen days corresponded with worse moods in those who generally had worse moods in the summer. Allergies elicit an immune response and inflammatory processes that may contribute to depression; studies have found evidence that having allergies is associated with higher odds of depression.

Psychiatrist Normal Rosenthal says he’s had patience that say the brightness in summer ‘cuts through them like a knife’ (Getty)

Hot, sticky weather and the threat of pollen-induced allergies is probably unpleasant to everyone. One study surveying 1.9 million Americans found that higher temperatures eroded mental well-being; as temperatures crept above 21C (70F), negative emotions and fatigue increased while positive emotions decreased.

Why some people are more vulnerable to summer depression is “the million-dollar question”, Rohan said.

These environmental stressors challenge our interior environment, Rosenthal said. “We have these homeostatic or self-adjusting mechanisms,” he said. “But clearly in some people, they don’t work as well as in other people.”

Some of the key neurotransmitters involved in regulating our body temperature, such as serotonin, dopamine and norepinephrine, also regulate our mood, Rohan said. “So maybe it’s a shared vulnerability to a mood disorder and an issue with the ability to thermal regularly in response to heat and humidity,” she said.

Summer SAD may become more prominent and pervasive in a warming world, researchers say.

Rohan said that in the past, she never got any news media calls about summer depression. Now, there is a lot more interest.

“I will make a prediction that summer SAD certainly has increasing importance considering global warming, raising concerns regarding increased exposure to the assumed triggers heat and humidity,” Rohan said. “I strongly suspect that we’re going to see more cases of this popping up.”

Already, climate change is disrupting mental health.

Heatwaves, which are exacerbated by climate change, have been linked to worse mental health outcomes. Higher temperatures are linked with more mental health emergency room visits, suicides and poor self-reported mental health.

If you feel especially down in the summer, it is important to acknowledge those feelings and seek medical help.

“People really need to be aware that suicidal feelings are more common,” Rosenthal said. “And then they should really go get help if that’s happening.”

Cooling off may help, though there have not yet been clinical trials testing this method. Rosenthal and his colleagues recommended patients with summer depression take cold showers and stay in air-conditioned places. This intuitive intervention seemed to work and alleviated his patients’ symptoms.

These effects, though, only lasted as long as the patients stayed cool; once his patients returned outside to the summer heat, the effect seemed to evaporate.

With winter SAD, clinical trials have found light therapy to be effective with relatively few side effects. Its effects are persistent, too.

“The effects of light seem to have an enduring carry-over effect” of several days, Rosenthal said. The cooling treatment for summer depression, however, “didn’t seem to have the same inertia or persistence that we see with the light therapy and winter depression.”

Summer depression is depression, and there are effective treatments for depression, Rohan said. Psychiatric drugs that work for major depression also can work for seasonal depression.

“One value of knowing when people get depressed is you can anticipate it and pre-empt it to some degree,” said Rosenthal, who added that he may ramp up antidepressants for patients in the months leading up to their problem season.

Combining different treatments – cooling strategies, medication and evidence-based psychotherapy, such as cognitive behaviour therapy – may be the key to beating summer sadness.

© The Washington Post