The Science Behind Seasonal Depression

Those who suffer from seasonal depression meet the criteria for clinical depression, but they see their symptoms improve with the onset of warmer seasons...Photo Illustration by Chris Fertnig, Getty Images

When he moved from South Africa to New York City, Norman Rosenthal noticed he felt more depressed during the cold, short days of the city’s winters than he had in his home country. “It was an illness hiding in plain sight because people said ‘well that’s how everyone feels in winter.’ They didn’t see it as treatable,” says Rosenthal, a psychiatrist at Georgetown Medical School.

In 1984, he published the first paper to scientifically name the winter blues: Seasonal affective disorder (SAD), also called seasonal depression, was a type of depression brought on by the dark days of winter. Subsequent studies have found that this form of depression varies by geography. As much as three percent of the general population is thought to experience SAD, but one study Rosenthal published in 1990 found that the condition became more prevalent in the U.S. in northern latitudes, with as many as 10 percent of New Hampshire residents reporting the condition.

And, surprisingly, about 10 percent of patients suffering from SAD have symptoms in the summertime instead. Whether in winter or summer, mental health experts say there are solutions to treat SAD.

A bad mood versus a SAD mood

It’s normal for moods to fluctuate with seasons and even for people to feel a little more down in the winter, experts say, but those suffering from SAD experience the symptoms of clinical depression. “They’re exactly the same,” says Kelly Rohan, a psychologist at the University of Vermont who specializes in the disorder.

“We would look for things like a persistently sad mood. Losing interest in things. Sleep changes. Significant eating or appetite change. Losing energy. Fatigue. Difficulty concentrating,” she says. At Yale’s Winter Depression Research Clinic, the most commonly reported symptoms of winter depression are hypersomnia—the desire to sleep more than usual—and an increased appetite, says Paul Desan, a psychiatrist and the clinic’s director.

“It’s like human beings are trying to hibernate,” says Desan. Most people begin experiencing symptoms in young adulthood, but SAD can begin at any stage of life. The condition also varies by sex. “About three times as many women as men get SAD for reasons we don’t understand,” says Desan…..Continue reading

Source: The science behind seasonal depression

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Seasonal affective disorder (SAD) is a mood disorder subset, in which people who have normal mental health throughout most of the year exhibit depressive symptoms at the same time each year, commonly but not always in the wintertime, with reduced sunlight.Common symptoms include sleeping too much, having little to no energy, and overeating.The condition in the summer can include heightened anxiety.

In the Diagnostic and Statistical Manual of Mental Disorders DSM-IV and DSM-5, its status was changed. It is no longer classified as a unique mood disorder, but is now a specifier, called “with seasonal pattern“, for recurrent major depressive disorder that occurs at a specific time of the year, and fully remits otherwise.

Although experts were initially skeptical, this condition is now recognized as a common disorder. However, the validity of SAD has been questioned by a 2016 analysis by the Center for Disease Control, in which no links were detected between depression and seasonality or sunlight exposure.

In the United States, the percentage of the population affected by SAD ranges from 1.4% of the population in Florida, to 9.9% in Alaska.^[8] SAD was formally described and named in 1984, by Norman E. Rosenthal and colleagues at the National Institute of Mental Health.