Bright green light treatment of depression for older adults [ ISRCTN 69400161 ] Richard

Background: Bright white light has been successfully used for the treatment of depression. There is interest in identifying which spectral colors of light are the most efficient in the treatment of depression. It is theorized that green light could decrease the intensity duration of exposure needed. Late Wake Treatment (LWT), sleep deprivation for the last half of one night, is associated with rapid mood improvement which has been sustained by light treatment. Because spectral responsiveness may differ by age, we examined whether green light would provide efficient antidepressant treatment in an elder age group. Methods: We contrasted one hour of bright green light (1,200 Lux) and one hour of dim red light placebo (<10 Lux) in a randomized treatment trial with depressed elders. Participants were observed in their homes with mood scales, wrist actigraphy and light monitoring. On the day prior to beginning treatment, the participants self-administered LWT. Results: The protocol was completed by 33 subjects who were 59 to 80 years old. Mood improved on average 23% for all subjects, but there were no significant statistical differences between treatment and placebo groups. There were negligible adverse reactions to the bright green light, which was well tolerated. Conclusion: Bright green light was not shown to have an antidepressant effect in the age group of this study, but a larger trial with brighter green light might be of value. Background Bright white light has been shown to suppress melatonin, shift circadian rhythms and alleviate depression. Evidence suggests that green light may have effects similar to those of white light but could be more efficient [1-4] Recent studies have suggested that lower photon densities of blue light are required to suppress melatonin or to shift circadian phase than green, yellow, or red light [5-8]. It has been suggested that ganglion cells supplying the retinohypothalamic tract may be particularly responsive to blue light because they contain the blue-light-absorbing photopigment, melanopsin [9,10]. Retinohypothalamic transmission is key to light suppression of melatonin and to light-induced circadian phase shifting. However, there are reasons for skepticism that blue light is the best choice Published: 09 November 2005 BMC Psychiatry 2005, 5:42 doi:10.1186/1471-244X-5-42 Received: 13 May 2005 Accepted: 09 November 2005 This article is available from: http://www.biomedcentral.com/1471-244X/5/42 © 2005 Loving et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.