The patients continued morning light therapy during l-tryptophan treatment. Side effects were recorded at each follow-up visit. A total of 16 patients began the l-tryptophan augmentation phase. All had a unipolar diagnosis. The mean SD SIGH-SAD scores at baseline and after 2 weeks of light therapy alone were 31.5 7.1 and 26.4 7.6, respectively.
Bars represent mean scores.
All side effects were mild and did not affect treatment. The 14 patients who completed the l-tryptophan trial had a few mild side effects to the medication. These results suggest that l-tryptophan augmentation may be a useful clinical strategy for patients with SAD who show limited response to light therapy alone. This conclusion must be considered tentative, however, since we used an open-label study design, and therefore nonspecific or placebo effects cannot be ruled out. Since we continued light therapy during l-tryptophan administration, it is also possible that the clinical improvement seen during the combined treatment resulted from the longer trial of light therapy.