This article's citation style may be unclear. The references used may be made clearer with a different or consistent style of citation, footnoting, or external linking. (September 2009)

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 circadian 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:^[1]

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)

[edit] Clinical pharmacology

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,^[2][3] as shown during controlled light-dark cycles, even for some blind subjects, indicating that melanopsin is responsible for circadian entrainment in humans.^[4]

[edit] Bipolar disorder treatment

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.^[5] Further examinations were done on single patients, and are reported on the link regarding 24hr biological clocks.^[6] A study regarding 48 hour cycles has also been reported.^[7]

[edit] Other conditions

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 fibromyalgia.^[8]

Melatonin secreted is preventative in cancer, and supportive of bone metabolism, immune function and detoxification.^[9] Melatonin has also been cited to reduce hypertension, produce better sleep for those with insomnia, and acts as an antioxidant.^[3]

[edit] Virtual darkness

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".^[10]

[edit] Side effects

No side effects have been officially reported for dark therapy.

[edit] Treatment constraints

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.

[edit] See also

• Benzodiazepine
• Clinical depression
• Light therapy
• Migraine
• Sleep hygiene
• Sunglasses

[edit] References

[edit] External links

• PhotoperiodEffect