Importance of Timing and Duration of Phototherapy-Reply

Reply. —  were interested to hear about Dr Stewart's work with phototherapy of seasonal affective disorder. He raises an important question about the results of our study, in which we found that the antidepressant effects of long and short skeleton photoperiods were similar.¹ We concluded that both types of treatment were effective and, therefore, that the timing of treatments was not a critical factor for their antidepressant effect. Noting the absence of a sham control treat- ment, Dr Stewart suggests that both treatments may have been ineffective and that the results may provide little information about the importance of timing of phototherapy. We discussed the problem of the absence of a control treatment in our study. However, when our results are compared with those of controlled phototherapy studies,^2-9 our patients' responses to both skeleton photoperiods appear similar to responses to active treatments, not control treatments, in these studies