Psychotherapy may be a better remedy for people with seasonal affective disorder than light therapy, a new study suggests.

Researchers in British Columbia estimate about two per cent of Canadians suffer from SAD, a form of depression that occurs during the darker, colder months.

Like many mental illnesses, SAD can be treated and managed by various methods, including light therapy, medication and cognitive behaviour therapy. Those with less severe cases can often find some relief through regular exercise and outdoor activity.

In the September issue of the journal Behavior Therapy, Kelly Rohan, a psychologist at the University of Vermont, and her colleagues compared the treatments in 69 people with SAD randomly assigned to receive light therapy, psychotherapy, both or nothing.

Six weeks after treatment started, 80 per cent of those receiving combination therapy were in remission, compared to 50 per cent for cognitive behaviour therapy and the same for light therapy. About 20 per cent of those in the control group experienced remission.

Psychotherapy more 'practical, palatable'

Bright light or phototherapy involves sitting in front of a light box of fluorescent bulbs with eyes wide open for about 30 minutes a day. A screen over the bulbs filters out harmful ultraviolet rays.

The light emitted is thought to cause a biochemical change in the brain to lighten mood and improve symptoms of SAD.

Another approach, known as cognitive behaviour therapy, is a type of counselling that focuses on changing attitudes, thoughts and behaviour patterns that contribute to SAD.

When the researchers looked at recurrence of SAD one year after the first treatment, they found:

• 5.5 per cent of those receiving the combo therapy had a recurrence.
• 7 per cent of those receiving cognitive behaviour therapy alone did.
• 36.7 per cent of those treated with a light box had SAD symptoms return.

The decline among those using only light therapy could be because it was inconvenient to use every day, the researchers speculated. Of those in the study, four continued to use their light box the next winter.

"If these findings are replicated, CBT could represent a more effective, practical, and palatable approach to long-term SAD management than light therapy," the study's authors concluded.

People with SAD tend to experience their first symptoms in October or November. Daylight Saving Time ends on Sunday.