Study

PRESENTED BY DR. ANTHONY LEVITT, M.D., F.R.C.P.(C)
AT THE CANADIAN PSYCHIATRIC ASSOCIATION CONFERENCE
MONTREAL, P.Q. SEPTEMBER 16, 1992
ABSTRACT

Several investigators have suggested that RED LIGHT may not be as effective as other wavelengths of light, in the treatment of Seasonal Affective Disorder (SAD). Therefore, RED LIGHT has been advanced as an appropriate placebo for trials of efficacy of light therapy. However, most studies have compared DIM red light and bright white from a standard light box. Since dim white light is inferior to bright white light from a light box, the finding that red light is less effective is not surprising. To date, no studies have evaluated the efficacy of bright red light therapy in SAD.

Subjects were consecutive outpatients with DSM-III-R major depression, seasonal subtype, confirmed by the Structured Clinical Interview for DSM-III-R. Patients received the Hamilton Rating Scale for Depression, SAD Version (SIGH-SAD) and were included if they scored more than 12 on the "Typical" items, or greater than 18 on all 25 items. Those subjects who were taking psychotropic medications were included if they had been stable on medications for at least 4 weeks. Light was delivered using Light Emitting Diode (LED) lights mounted into the brim of a cap (HEALTH LIGHT INC., CANADA). Each subject was randomly allocated to receive two weeks of either dim red (Mean lux = 86) or bright red (Mean lux = 1432) light followed by one week washout period, and they were not aware of the exact intensity of light they were receiving. Side effects were monitored using the Light Visor Side Effect Questionnaire. The SIGH-SAD was repeated weekly and response defined by a 50% reduction in both typical and atypical scores. Two patients, one from each group, dropped out before completion of the treatment.

Of the 43 patients who completed the study, 19 had dim and 24 bright light. There was no significant difference the number of responders between subjects treated with dim (68%) versus bright (67%), nor was there a difference in percent change in SIGH-SAD scores. Furthermore, the percentage number of responders in this study was similar to patients treated in previous studies at our site using incandescent light (60%).

These findings suggest that dim and bright RED LIGHT are similarly effective in treating SAD and that when delivered using LED light from a light visor have equivalent efficacy as compared with previously studied light units. (Emphasis added)

ALSO SEE ABSTRACT:
THE PHOTOTHERAPY LIGHT VISOR: THERE IS MORE TO IT THAN MEETS THE EYE.
{SLTBR ABSTRACTS, VOLUME 4, 1992}