Vol 5 n° 4 - Chronobiology and Mood Disorders
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Initial studies n 1981, Kripke1 exposed seven nonseasonally depressed patients to bright white light shortly before their  usual  time  of  arising.  Depression  scores  were reduced on the following day. In a subsequent study,2 5 new subjects were added, for a total of 12 subjects, includ- ing 11 males with major depressive disorder (MDD) (3 with bipolar illness) according to research diagnostic cri- teria  (RDC),3  who  were  on  an  inpatient  psychiatric research ward. In counterbalanced order, the investiga- tors administered either bright white light (1000 to 2000 lux) or dim red light (less than 25 lux) for 1 h, 2 h before the subject’s usual time of arising. The bright white light treatment produced significantly lower depression scores on both the Hamilton4 and Beck5 ratings as compared with  baseline.  A  follow-up  pilot  experiment  of  12 depressed inpatients6 showed that there was no indica- tion that 1 h awakening with exposure to dim red light (25 lux) had any antidepressant effect. After demonstrating that sunlight and bright artificial light could suppress human melatonin secretion, Lewy et al7 reported on a patient with a bipolar II seasonal mood cycle whose winter depression remitted when his hours of daylight were lengthened with bright fluorescent light (Vital-Lite) of 2000 lux between his time of awakening (6.00 AM) and 9.00 AM, and between 4.00 PM and 7.00 PM, thereby extending his daylength (photoperiod) to 13 h (a spring photoperiod). During light exposure, melatonin levels declined by 88% between 1.00 and 5.00 AM. Winter depression has been found to improve when patients are exposed to bright full-spectrum light before dawn and after dusk, thereby extending the photope- riod.8,9 Bright light consisted of 2500 lux of full-spectrum light; dim light was 300 lux. Light was administered from 5.00 AM to 8.00 AM, and 5.30 PM to 8.30 PM every day. Bright light had a marked antidepressant effect, whereas P h a r m a c o l o g i c a l   a s p e c t s 3 5 3 Light treatment of mood disorders Barbara L. Parry, MD; Eva L. Maurer, BS I In 1981, seven patients with nonseasonal depression were treated with bright white light. In 1982, bright artificial light was used to treat a manic-depressive patient with a seasonal mood cycle. In the last 20 years, a plethora of studies have further defined the depressive populations, who are responsive to light treatment; the optimal tim- ing, intensity, spectral frequency, and duration of treat- ment; its comparison with other pharmacological inter- ventions; predictors of response; side-effect profiles; viable placebo-control conditions; alternative devices and forms of administration; potential mechanisms and anatomical pathways mediating light’s physiological effects; and its application to other disorders and subsyndromal states. These studies have been conducted across multiple coun- tries with surprisingly consistent results. Further work is needed, as highlighted in this review, to clarify the specific mechanism of action in subtypes of depressive disorders and differential age and gender effects. Although the majority of work in this area is relatively new, it behooves the reader to remember that Solomon, almost 3000 years ago, wrote in Ecclesiastes: “Truly the light is sweet and a pleasant thing it is for the eyes to behold the sun” (11:7). © 2003, LLS SAS Dialogues Clin Neurosci. 2003;5:353-365. Keywords: light treatment; phototherapy; mood disorder; depression; seasonal affective disorder Author  affiliations:  Department  of  Psychiatry,  University  of  California,  San Diego, 9500 Gilman Drive, La Jolla, Calif, USA Address  for  correspondence:   Department   of   Psychiatry,  University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0804, USA (e-mail: bparry@ucsd.edu) Copyright © 2003 LLS SAS.  All rights reserved www.dialogues-cns.org