Posted by desolationrower on April 9, 2009, at 17:23:09
In reply to Re: Question about sunlight,UV rays,depression etc., posted by Phillipa on April 9, 2009, at 16:39:17
BLUE LIGHT _NOT_ UV LIGHT NEEDS TO HIT YOUR EYES.
BLUE.
Variations in the wavelength spectrum of light
have received relatively little study. Although
the earliest studies
2
used full-spectrum fluorescent
lampswith more blue and ultraviolet (UV) A
energy than conventional cool- and soft-white
broad-spectrum fluorescent lampsthese were soon
found unnecessary.
18-20
Finer distinctions between
lamp types have focused on the action of narrow
wavelength bands. A comparison of efficacy of
non-overlapping green and red fluorescent illu-
mination equated for quantum emission
21
found
minimal response to red, while green produced a
response similar to that of broad-spectrum white
light. A related comparison
22
found white light bet-
ter than both red and blue. These studies left open
the question of whether the white-light response
is primarily determined by its green component.
Recent attention has focused on the blue region,
which actively suppresses melatonin production
23
and elicits circadian rhythm phase shifts.
24,25
In a
comparison of blue light with red light of lower
intensity (designed as a placebo control), the anti-
depressant response to blue was superior, similar to
that seen for white light in other studies.
26
Whether
there is a therapeutic advantage to narrow-band
green or blue over white illumination requires fur-
ther study, particularly regarding their tolerability
and adverse effects.ABSTRACT
The general therapeutic effect of light on seasonal affective disorder (SAD) has been widely acknowledged. However, the antidepressant effect of light does not seem to be the same for different spectra of light. In this study, the authors attempted to study the spectral properties of phototherapy for SAD using a meta-analytical procedure. The findings suggested that light of short to medium wavelengths (blue/green/yellow) seem to be essential for the therapeutic effect of light on SAD. Red wavelengths were relatively ineffective. It was then postulated that SAD may be predisposed and/or precipitated by the inefficiency of the S and M cones in the retina. Furthermore, ultraviolet (UV) waves did not seem to be essential for SAD symptom alleviation by artificial light. Therefore, these potentially harmful UV waves should be blocked in any clinical application of phototherapy for SAD.
Dark therapy for bipolar disorder using amber lenses for blue light blockade
James PhelpsCorresponding Author Informationemail address
Received 19 May 2007; accepted 22 May 2007. published online 16 July 2007.
SummaryDark Therapy, in which complete darkness is used as a mood stabilizer in bipolar disorder, roughly the converse of light therapy for depression, has support in several preliminary studies. Although data are limited, darkness itself appears to organize and stabilize circadian rhythms. Yet insuring complete darkness from 6 p.m. to 8 a.m. the following morning, as used in several studies thus far, is highly impractical and not accepted by patients. However, recent data on the physiology of human circadian rhythm suggests that virtual darkness may be achievable by blocking blue wavelengths of light. A recently discovered retinal photoreceptor, whose fibers connect only to the biological clock region of the hypothalamus, has been shown to respond only to a narrow band of wavelengths around 450nm. Amber-tinted safety glasses, which block transmission of these wavelengths, have already been shown to preserve normal nocturnal melatonin levels in a light environment which otherwise completely suppresses melatonin production. Therefore it may be possible to influence human circadian rhythms by using these lenses at night to blunt the impact of electrical light, particularly the blue light of ubiquitous television screens, by creating a virtual darkness. One way to investigate this would be to provide the lenses to patients with severe sleep disturbance of probable circadian origin. A preliminary case series herein demonstrates that some patients with bipolar disorder experience reduced sleep-onset latency with this approach, suggesting a circadian effect. If amber lenses can effectively simulate darkness, a broad range of conditions might respond to this inexpensive therapeutic tool: common forms of insomnia; sleep deprivation in nursing mothers; circadian rhythm disruption in shift workers; and perhaps even rapid cycling bipolar disorder, a difficult- to -treat variation of a common illness.
ABSTRACT
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.
Narrow-band blue-light treatment of seasonal affective disorder in adults and the influence of additional nonseasonal symptoms
Robert E. Strong, D.O. *, Barrie K. Marchant, M.S., Frederick W. Reimherr, M.D., Erika Williams, M.S.W., Poonam Soni, M.D., Ruth Mestas, CCRC
Mood Disorders Clinic, Department of Psychiatry, University of Utah Health Sciences Center, Salt Lake City, Utah
email: Robert E. Strong (robert.strong@hsc.utah.edu)*Correspondence to Robert E. Strong, Mood Disorders Clinic, Department of Psychiatry, University of Utah Health Sciences Center, Salt Lake City, Utah 84132
Keywords
seasonal affective disorder wavelength light therapy placebo-controlled randomizedAbstract
Background: Bright visible-spectrum light therapy has proven effective in the treatment of seasonal affective disorder (SAD) and recent basic research suggests that blue wavelengths 470 nm account for that effectiveness. To more stringently test the importance of these wavelengths, bright red-light was used for the placebo (control) condition. Methods: Thirty subjects meeting DSM-IV criteria for SAD were randomized to narrow-band light-emitting diode panels emitting blue- or red-light in this 3-week, parallel, double-blind trial. Twenty-five subjects participated in an open-label blue-light follow-up. Subjects were divided in a blinded, post hoc manner into two groups: SAD only and those experiencing depression with seasonal intensification. The outcome was assessed using Hamilton Depression Rating Scale-17 item version (HAMD-17) and the Structured Interview Guide for the Hamilton Depression Rating Scale - SAD version. Responders were defined by Clinical Global Impression - Improvement scale. Results: HAMD-17 scores improved more under the blue-light condition (51%) than under the red-light condition (32%) (P=.05). Further, in the blue arm 60% of subjects responded compared with 13% in the red arm (P=.01). During the open-label phase, subjects from both double-blind arms improved over baseline. SAD alone patients responded numerically better to treatment than those experiencing depression with seasonal intensification during both treatment periods. Conclusions: Narrow bandwidth blue-light therapy proved superior to red-light therapy. Blue-light therapy produced results similar to both previous 10,000 lux visible-spectrum light studies and many medication studies. The use of bright red panels supported claims that wavelengths of 470 nm account for the documented effectiveness of light therapy. Depression and Anxiety, 2009. © 2008 Wiley-Liss, Inc.
poster:desolationrower
thread:889657
URL: http://www.dr-bob.org/babble/20090408/msgs/889690.html