Lux vs. wavelength in light treatment of Seasonal Affective Disorder
Published dosing guidelines for treatment of Seasonal Affective Disorder (SAD) refer to photopic lux, which is not appropriate for short-wavelength light. Short wavelengths are most potent for many non-visual responses to light. If SAD therapy were similarly mediated, standards utilizing lux risk overestimating necessary dose. We investigated antidepressant responses to light using two light-emitting diode (LED) sources, each emitting substantial short-wavelength light, but <2500 lux. Method:
A randomized, double-blind trial investigated 3-week 45 min/day out-patient treatment with blue-appearing (goLITE®) or blue-enriched white-appearing light in 18 moderately-depressed adults (12F, 49.1 ± 9.5 years). Equivalent numbers of photons within the short-wavelength range were emitted, but the white source emitted twice as many photons overall and seven-fold more lux. Results:
Depression ratings (SIGH-ADS; http://www.cet.org) decrease averaged 82% (SD = 17%) from baseline (P < 0.0001) in both white- and blue-light groups. Both sources were well tolerated. Conclusion:
Short-wavelength LED light sources may be effective in SAD treatment at fewer lux than traditional fluorescent sources.
Document Type: Research Article
Affiliations: 1: Department of Psychiatry, Brigham & Women’s Hospital and Harvard Medical School, Boston, MA, USA 2: School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston, MA, USA 3: School of Nursing, Bouvé College of Health Sciences, Northeastern University, Boston, MA, USA 4: Department of Medicine, Division of Sleep Medicine, Brigham & Women’s Hospital and Harvard Medical School, Boston, MA, USA
Publication date: 2009-09-01