Document Type

Article

Publication Date

March 2006

Comments

This article has been peer-reviewed. It was published in Biological Psychiatry 59(6):502-7, March 15, 2006. The published version is available at http://dx.doi.org/10.1016/j.biopsych.2005.07.006. Copyright is retained by Elsevier Science, Inc.

Abstract

Background: While light has proven an effective treatment for Seasonal Affective Disorder (SAD), an optimal wavelength combination has not been determined. Short wavelength light (blue) has demonstrated potency as a stimulus for acute melatonin suppression and circadian phase shifting.

Methods: This study tested the efficacy of short wavelength light therapy for SAD. Blue light emitting diode (LED) units produced 468 nm light at 607 µW/cm2 (27 nm half-peak bandwidth); dim red LED units provided 654 nm at 34 µW/cm2 (21 nm half-peak bandwidth). Patients with major depression with a seasonal pattern, a score of ≥20 on the Structured Interview Guide for the Hamilton Depression Rating Scale-SAD version (SIGH-SAD) and normal sleeping patterns (routine bedtimes between 10:00 pm and midnight) received 45 minutes of morning light treatment daily for 3 weeks. Twenty-four patients completed treatment following random assignment of condition (blue vs. red light). The SIGH-SAD was administered weekly.

Results: Mixed-effects analyses of covariance determined that the short wavelength light treatment decreased SIGH-SAD scores significantly more than the dimmer red light condition (F = 6.45, p = .019 for average over the post-treatment times).

Conclusions: Narrow bandwidth blue light at 607 µW/cm2 outperforms dimmer red light in reversing symptoms of major depression with a seasonal pattern.

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