From Wikipedia, the free encyclopedia
Dark therapy is an experimental treatment which
involves eliminating all light in the subject's environment, for a
period of six to sixteen hours per day, in combination with a
regular sleep schedule. Dark therapy manipulates
rhythms acting on hormones and neurotransmitters. It has been proposed
recently (2005) to combine the chronobiological manipulations of
light/dark and/or sleep/wake therapies with psychopharmacological
medication. In the words of Anna Wirz-Justice:
- Light therapy has undergone widespread controlled
randomized clinical trials, and wake therapy has been so widely
studied over decades that the efficacy data are strong. These
nonpharmaceutical, biologically based therapies are not only
powerful adjuvants, but also antidepressants in their own
right. (Page 223)
- [P]ilot studies suggest that the simple measure of
promoting long nights (more rest, more sleep, no light) can stop
rapid cycling in bipolar patients, or diminish manic symptoms —
intriguing findings that require replication. (Page 226)
Researchers hypothesize that benefits of being in the dark are
due to melatonin
production by the pineal gland, which occurs when the eyes
are deprived of light,
as shown during controlled light-dark cycles, even for some blind
subjects, indicating that melanopsin is responsible for circadian entrainment in humans.
A single small scale study done in Hospital San Raffaele of
Milan, Italy, concluded that chronobiological interventions and
control of environmental stimuli can be a useful add-on for the
treatment of acute mania in a hospital setting. Further
examinations were done on single patients, and are reported on the
link regarding 24hr biological clocks. A study
regarding 48 hour cycles has also been reported.
Dark therapy has also been tried (in combination with bright light therapy, etc)
for other conditions where seasonal exacerbation of symptoms are
notable, such as nocturnal asthma and associated depression, migraine, dyssomnia, chronic fatigue syndrome and
Melatonin secreted is preventative in cancer, and supportive of
bone metabolism, immune function and detoxification.
Melatonin has also been cited to reduce hypertension, produce
better sleep for those with insomnia, and acts as an
By using amber lenses, researchers were able to block blue
spectrum light, which affected the "physiology of human circadian
rhythm ... suggesting a circadian effect". This effect was
previously noted with "amber-tinted safety glasses" which "preserve
normal nocturnal melatonin levels in a light environment which
otherwise completely suppresses melatonin production".
No side effects have been officially reported for dark
When having dark hours at home or in a hospital, patients will
often be exposed to fewer light-hours than in their usual
environment, thus requiring a light tight environment. Light from
most sources could disrupt dark therapy. Also, it is necessary to
have dark therapy hours at specified times during each day.
Wirz-Justice A (2005). "Chronobiological strategies
for unmet needs in the treatment of depression".
Medicographia 27 (3): 223–7. http://www.cet.org/documents/pdf/wirz/Wirz%202005%20Medicographia.pdf.
Skene DJ, Arendt J (September 2006).
"Human circadian rhythms: physiological and therapeutic relevance
of light and melatonin". Ann. Clin. Biochem.
43 (Pt 5): 344–53. doi:10.1258/000456306778520142. PMID 17022876.
- ^ a
Macchi MM, Bruce JN (2004). "Human
pineal physiology and functional significance of melatonin".
Front Neuroendocrinol 25 (3-4): 177–95.
doi:10.1016/j.yfrne.2004.08.001. PMID 15589268.
Silva MM, Albuquerque AM, Araujo JF
(September 2005). "Light-dark cycle
synchronization of circadian rhythm in blind primates". J
Circadian Rhythms 3: 10. doi:10.1186/1740-3391-3-10. PMID 16144547. PMC 1208936. http://www.jcircadianrhythms.com/content/3/1/10.
Barbini B, Benedetti F, Colombo C,
Dotoli D, Bernasconi A, Cigala-Fulgosi M, Florita M, Smeraldi E
(February 2005). "Dark therapy for mania: a pilot study".
Bipolar Disord 7 (1): 98–101. doi:10.1111/j.1399-5618.2004.00166.x. PMID 15654938.
Biological Clocks and Bipolar
Voderholzer U, Weske G, Ecker S,
Riemann D, Gann H, Berger M (2002). "Neurobiological findings
before and during successful lithium therapy of a patient with
48-hour rapid-cycling bipolar disorder".
Neuropsychobiology 45 (Suppl 1): 13–9. doi:10.1159/000049256.
Durlach J, Pagès N, Bac P, Bara M,
Guiet-Bara A (March 2005). "Magnesium depletion with hypo- or
hyper- function of the biological clock may be involved in
chronopathological forms of asthma". Magnes Res
18 (1): 19–34. PMID 15945613.
Witt-Enderby PA, Radio NM, Doctor
JS, Davis VL (November 2006). "Therapeutic treatments potentially
mediated by melatonin receptors: potential clinical uses in the
prevention of osteoporosis, cancer and as an adjuvant therapy".
J. Pineal Res. 41 (4): 297–305. doi:10.1111/j.1600-079X.2006.00369.x. PMID 17014686.
Phelps J (2008). "Dark therapy for
bipolar disorder using amber lenses for blue light blockade".
Med. Hypotheses 70 (2): 224–9. doi:10.1016/j.mehy.2007.05.026. PMID 17637502.