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Dark Therapy

This article is about the medical uses for the absence of light. For alternative uses see Darkness (disambiguation).

Dark Therapy is an experimental treatment which involves eliminating all light in the subject's environment, for a period of six to sixteen hours, in combination with a regular sleep schedule. Dark therapy manipulates circadian rhythms to act 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.

Additional recommended knowledge

Daily Sensitivity Test

Weighing the right way

Clinical pharmacology

Researchers hypothesize that the benefits of being in the dark are due to melatonin production by the pineal gland, which occurs when the body is deprived of light,[1][2] as shown during controlled light-dark cycles, even for blind subjects, indicating that melanopsin is responsible for circadian entrainment in humans.[3]

Bipolar disorder treatment

There was a single small scale study done in Hospital San Raffaele of Milan, in Italy, which 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. [4] Further examinations were done on single patients, and are reported on the link regarding 24hr biological clocks [5]. A study regarding 48 hour cycles has also been reported [6]

Other conditions

Dark Therapy has also been tried (in combination with bright light therapy, etc) for other conditions where seasonal exacerbation of symptoms in notable, such as nocturnal asthma, and associated depression, migraine, dyssomnia, chronic fatigue syndrome and fibromyalgia.[7]

Melatonin secreted is preventative in cancer, and supportive of bone metabolism, immune function and detoxification.[8]Melatonin has also been cited to reduce hypertension, produce better sleep for those with insomnia, and acts as an antioxidant.[9]

Virtual darkness

By using amber lenses, researchers were able to block blue spectrum light, which affected "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". PMID 17637502

Side effects

No side effects have been officially reported for Dark Therapy.

Treatment constraints

When having dark hours in at home or hospital, patients will often be exposed to a lower number of light hours than in their usual environment, so they need to make the environment light tight. Light from most sources could disrupt dark therapy. Also, it is necessary to have dark therapy hours at the specified times during each day.

References

Dark therapy for bipolar disorder using amber lenses for blue light blockade. PMID 17637502

Wirz-Justice, Anna. Chronobiological strategies for unmet needs in the treatment of depression. MEDICOGRAPHIA, VOL 27, No. 3, 2005 p. 223-227 [10]

Human circadian rhythms: physiological and therapeutic relevance of light and melatonin. PMID: 17022876

Human pineal physiology and functional significance of melatonin. PMID: 15589268

Light-dark cycle synchronization of circadian rhythm in blind primates. Journal of Circadian Rhythms 2005, 3:10 (6 September 2005)

Dark therapy for mania: a pilot study. Bipolar Disord. 2005 Feb;7(1):98-101. PMID: 15654938

Neurobiological Findings Before and During Lithium of a Bipolar Patient with Rapid Cycling PMID: 11893872

Magnesium depletion with hypo- or hyper- function of the biological clock may be involved in chronopathological forms of asthma. PMID: 15945613

Therapeutic treatments potentially mediated by melatonin receptors: potential clinical uses in the prevention of osteoporosis, cancer and as an adjuvant therapy. PMID: 17014686

Human pineal physiology and functional significance of melatonin. PMID: 15589268