Sher L, Matthews JR, Turner EH, Postolache TT, Katz KS, Rosenthal NE.
Section on Biological Rhythms, National Institute of Mental Health, Bethesda, Md., USA.
J Psychiatry Neurosci. 2001 Sep;26(4):336-8.

OBJECTIVE: To determine if the antidepressant effect of 1 hour of light therapy is predictive of the response after 1 and 2 weeks of treatment in patients with seasonal affective disorder (SAD).
PATIENTS: Twelve patients with SAD.
SETTING: National Institutes of Health Clinical Center, Bethesda, Md.
INTERVENTIONS: Light therapy for 2 weeks.


OUTCOME MEASURES: Scores on the Seasonal Affective Disorder Version of the Hamilton Depression Rating Scale (SIGH-SAD) on 4 occasions (before and after 1 hour of light therapy and after 1 and 2 weeks of therapy) in the winter when the patients were depressed. Change on typical and atypical depressive scores at these time points were compared.
RESULTS: Improvement of atypical depressive symptoms after 1 hour of light therapy positively correlated with improvement after 2 weeks of therapy.
CONCLUSION: In patients with SAD, the early response to light therapy may predict some aspects of long-term response to light therapy, but these results should be treated with caution until replicated.