When shorter days and dark afternoons trigger depression, here are ways to fight back

Seasonal depression in winter

Seasonal affective disorder, or SAD, affects millions of people, according to estimates. Episodes commonly start in fall and improve in spring or summer. A milder form, subsyndromal SAD, is recognized by medical experts; seasonal depression can also occur in summer, although less is known about it.

The return to standard time, which happened Sunday across much of the U.S., is one trigger associated with SAD because it brings darker afternoons. No single cause has been identified. The NIH says the disorder affects many more women than men, and symptoms can include persistent hopelessness or pessimism and trouble concentrating, remembering or making decisions.

What researchers are studying

Scientists are examining specialized cells in the eyes that turn blue wavelengths of light into neural signals that influence mood and alertness. Sunlight contains abundant blue light; absorbing it activates brain alertness centers and can make people feel more awake and possibly happier.

Dr. Norman Rosenthal, then a National Institutes of Health researcher, led the team that first described SAD in 1984 and coined the term. Rosenthal said the acronym had endured because it was easy to remember.

Light therapy and treatment

Many people with SAD respond to light therapy, said Dr. Paul Desan of Yale University's Winter Depression Research Clinic. Research supports using a device rated at about 10,000 lux for 30 minutes each morning. Desan said the approach may also help people with milder winter blues.

Devices can cost from $50 to more than $400, and some products marketed for SAD are too dim to be effective, Desan said. Yale has tested products and provides recommendations; the nonprofit Center for Environmental Therapeutics also offers a consumer guide. People diagnosed with SAD can ask their insurance company whether a light's cost may be covered.

Antidepressant medication is a first-line treatment alongside light therapy. Doctors also recommend maintaining a regular sleep schedule and walking outside, including on cloudy days. The benefits of light therapy can fade after people stop using it.

Therapy and everyday steps

Studies have found that cognitive behavioral therapy, or CBT, can have more lasting effects, said Kelly Rohan, a University of Vermont researcher. CBT involves working with a therapist to identify and change unhelpful thoughts.

Rohan said therapy can help people take small steps toward enjoying activities again. One suggestion is to plan manageable, enjoyable outings, such as meeting a friend for coffee, to help break out of hibernation mode.