A new evaluation of scientific research on the subject by the Swedish Council on Technology Assessment in Health Care (SBU) said that, despite plenty of research, there is still little evidence that light therapy has an effect on lethargy during the dark days of winter.
Psychiatric clinics in most parts of Sweden offer light therapy, and many patients report that the treatment has helped them. Light therapy also has the advantage of being almost entirely free of side effects.
SBU’s report concluded that the widespread use of light therapy meant that “resources should be made immediately available” for an in-depth study to give a definitive verdict on the effects of the treatment.
The report’s authors also said that researchers should look at whether psychological treatment could have a positive effect on SAD. A small pilot study of cognitive behaviour therapy showed positive long term effects, but wider studies are needed. Examination of the use of light therapy for patients on anti-depressants was also needed.
Many Swedes suffer from depression during the winter months, reporting tiredness and dejection, but the causes of the phenomenon are unclear.
The term Seasonal Affective Disorder was coined in the 1980s by American psychiatrist Norman Rosenthal, who explained the condition by saying that the lack of sunlight caused hormonal changes and disrupted the biological clocks of certain sensitive people.
Strangely, SAD is very unusual in Iceland, one of the countries with the darkest winters.