SUNDAY, Oct. 17 (HealthDayNews) -- The shorter days of fall and winter mean that millions of Americans with seasonal affective disorder (SAD) need to find ways to get enough light to fight off symptoms of depression.

Light therapy is an effective way of combating the depression linked with SAD, Ball State University psychologist Jay Zimmerman said in a prepared statement.

"There are specific lamps and light banks that can be purchased that give a full sunlight effect," he said.

People with SAD can also try to maximize their exposure to sunlight.

"If you work in an office with a window, leave the blinds open and sit next to the window so you can look out and let the sunlight into your eyes," Zimmerman said.

"One study found that an hour in winter sunlight was as effective as two and a half hours under bright artificial light. Also, if it is too cold to walk outside, find a place indoors where sunlight comes in and spend some time there taking in the sun during lunch or break," he said.

SAD, a disorder related to seasonal variations of sunlight, has been linked to melatonin, a sleep-related hormone secreted in the brain. Melatonin, which is produced at increased levels in the dark, may cause symptoms of depression.

The National Mental Health Association says that symptoms of SAD include:

• Regularly occurring symptoms of depression during the fall or winter.
• These symptoms have occurred in the past two years, with no nonseasonal depression episodes.
• Seasonal depression episodes greatly outnumber nonseasonal episodes.
• A craving for sugary and/or starchy foods.

"It is important not to diagnose yourself. A mental health professional or physician should be consulted. Symptoms can be linked to a number of other disorders. Medication and psychotherapy can be very helpful," Zimmerman said.

More information

The Cleveland Clinic Foundation has more about SAD and light therapy.