(HealthDayNews) -- Seasonal affective disorder (SAD) is a type of depression that appears as the days grow short and there's little sunlight.
The standard treatment is to increase your exposure to artificial light, but this only helps about 60 percent of people with the problem.
So psychiatrists from McGill University in Canada ran a trial to see if the amino acid tryptophan would help SAD sufferers. The Journal of Affective Disorders reports that just as many patients responded to tryptophan as to light therapy.
Some patients still didn't respond to either tryptophan or to light, but one patient who didn't improve with light therapy did improve on tryptophan.
And although the benefits of light therapy stopped quickly when it was discontinued, the benefits of tryptophan lasted for days after the last dose.
