Related Experiment Video
Updated: Jun 25, 2026

Method for the Assessment of Effects of a Range of Wavelengths and Intensities of Red/near-infrared Light Therapy on Oxidative Stress In Vitro
Published on: March 21, 2015
Lux vs. wavelength in light treatment of Seasonal Affective Disorder
J L Anderson1, C A Glod, J Dai
1Department of Psychiatry, Brigham & Women's Hospital and Harvard Medical School, Boston, MA 02115, USA. jlanderson@partners.org
Objective:
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.
Related Concept Videos
Depressive Disorders: MDD and Dysthymia
Light as Energy
Photons
A photon is a discrete electromagnetic particle or bundle of energy. Photons are characterized by their frequency, wavelength, and amplitude, similar to the properties of a wave. Waves with higher frequencies transmit more energy and have shorter wavelengths than longer wavelengths that transmit less...
Photoreceptors and Visual Pathways
Antidepressant Drugs: MAOIs and Other Agents
Electroconvulsive Therapy
The Wave Nature of Light