Spectral properties of phototherapy for seasonal affective disorder: a meta-analysis

T. M.C. Lee, Che Hin Chan, J. G. Paterson, H. L. Janzen, C. A. Blashko

Research output: Journal article publicationJournal articleAcademic researchpeer-review

39 Citations (Scopus)


The general therapeutic effect of light on seasonal affective disorder (SAD) has been widely acknowledged. However, the antidepressant effect of light does not seem to be the same for different spectra of light. In this study, the authors attempted to study the spectral properties of phototherapy for SAD using a meta-analytical procedure. The findings suggested that light of short to medium wavelengths (blue/green/yellow) seem to be essential for the therapeutic effect of light on SAD. Red wavelengths were relatively ineffective. It was then postulated that SAD may be predisposed and/or precipitated by the inefficiency of the S and M cones in the retina. Furthermore, ultraviolet (UV) waves did not seem to be essential for SAD symptom alleviation by artificial light. Therefore, these potentially harmful UV waves should be blocked in any clinical application of phototherapy for SAD.
Original languageEnglish
Pages (from-to)117-121
Number of pages5
JournalActa Psychiatrica Scandinavica
Issue number2
Publication statusPublished - 1 Jan 1997


  • Phototherapy
  • Seasonal affective disorder
  • Spectral analysis

ASJC Scopus subject areas

  • Psychiatry and Mental health


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