Light therapy for seasonal affective disorder with blue narrow-band light-emitting diodes (LEDs)

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 60 7 mu W/cm(2) (27 nm half-peak bandwidth); dim red LED units provided 654 nm at 34 mu W/cm(2) (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 pin 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 mu W/cm(2) outperforms dimmer red light in reversing symptoms of major depression with a seasonal pattern.