SAD: shedding light on seasonal sadness

With SAD light therapy, a patient sits in front of a light box for about 30 minutes a day. — Photo by
With SAD light therapy, a patient sits in front of a light box for about 30 minutes a day. — Photo by

NIH News in Health

As the days get shorter, many people find themselves feeling sad. Others experience serious mood changes that last throughout the fall and winter when there’s less natural sunlight. What is it about the darkening days that can leave us down in the dumps?

National Institute of Health-funded researchers have been studying the “winter blues” and a more severe type of depression called seasonal affective disorder, or SAD, for more than three decades.

“Winter blues is a general term, not a medical diagnosis. It’s fairly common, and it’s more mild than serious. It usually clears up on its own in a fairly short amount of time,” said Dr. Matthew Rudorfer, a mental health expert at NIH. The so-called winter blues are often linked to something specific, such as stressful holidays or reminders of absent loved ones.

“Seasonal affective disorder, though, is different. It’s a well-defined clinical diagnosis that’s related to the shortening of daylight hours,” Rudorfer said. “It interferes with daily functioning over a significant period of time.” A key feature of SAD is that it follows a regular pattern. It appears each year as the seasons change, and it goes away several months later, usually during spring and summer.

As with other forms of depression, SAD can lead to a gloomy outlook and make people feel hopeless, worthless and irritable. They may lose interest in activities they used to enjoy, such as hobbies and spending time with friends.

“Some people say that SAD can look like a kind of hibernation,” Rudorfer said. “People with SAD tend to be withdrawn, have low energy, oversleep and put on weight.” Without treatment, these symptoms generally last until the days start getting longer.

Shorter days seem to be a main trigger for SAD. Reduced sunlight in fall and winter can disrupt the body’s internal clock, or circadian rhythm. This 24-hour “master clock” responds to cues in one’s surroundings, especially light and darkness. During the day, the brain sends signals to other parts of the body to help keep it awake and ready for action. At night, a tiny gland in the brain produces a chemical called melatonin, which promotes sleep. Shortened daylight hours in winter can alter this natural rhythm and lead to SAD in certain people.

Light therapy is a standard treatment for SAD and replaces the missing daylight hours with an artificial substitute. In light therapy, patients generally sit in front of a light box every morning for 30 minutes or more, depending on the doctor’s recommendation.

Studies have shown that light therapy relieves SAD symptoms for as much as 70 percent of patients after a few weeks of treatment.

Light therapy is usually considered a first line treatment for SAD, but it doesn’t work for everyone. Studies show that certain antidepressant drugs can be effective in many cases of SAD.

Growing evidence suggests that cognitive behavioral therapy — a type of talk therapy — can also help patients who have SAD.
“For the cognitive part of CBT, we work with patients to identify negative self-defeating thoughts they have. The behavioral part of CBT tries to teach people new behaviors to engage in when they’re feeling depressed, to help them feel better,” said Dr. Kelly Rohan, a SAD specialist at the University of Vermont.

Behavioral changes might include having lunch with friends, going out for a walk or volunteering in the community.

If you’re feeling blue this winter, and the feelings last for several weeks, talk to a health care provider.

According to medical professionals, SAD is generally quite treatable, and the treatment options keep increasing and improving.