Melatonin : Part 2

by MedlinePlus

(Page 2 of 6)

Bipolar disorder (sleep disturbances)

There is limited study of melatonin given to patients with sleep disturbances associated with bipolar disorder (such as insomnia or irregular sleep patterns). No clear benefits have been reported. Further research is needed in this area before a clear conclusion can be reached.

Cancer treatment

There are several early-phase and controlled human trials of melatonin in patients with various advanced stage malignancies, including brain, breast, colorectal, gastric, liver, lung, pancreatic, and testicular cancer, as well as lymphoma, melanoma, renal cell carcinoma, and soft-tissue sarcoma. The same research group has conducted many of these studies.In this research, melatonin has been combined with other types of treatment, including radiation therapy, chemotherapies (such as cisplatin, etoposide, or irinotecan), hormonal treatments (such as tamoxifen), or immune therapies such as interferon, Interleukin-2, or tumor necrosis factor. Most of these trials have been published by the same research group, and have involved giving melatonin orally, intravenously, or injected into muscle. Results have been mixed, with some patients stabilizing and others progressing. There are some promising reported results, including small significant improvements in the survival of patients with non-small cell lung cancer given oral melatonin with chemotherapy (cisplatin and etoposide). However, the design and results of this research are not sufficient to provide definitive evidence in favor of safe/effective use of melatonin in cancer patients. High-quality follow-up trials are necessary to confirm these preliminary results.It has been proposed that melatonin may benefit cancer patients through antioxidant, immune-enhancing, hormonal, anti-inflammatory, anti-angiogenic, apoptotic, or direct cytotoxic (cancer cell-killing) effects, and there are many ongoing laboratory and animal studies in these areas. Some experts believe that antioxidants can improve the effectiveness of chemotherapy drugs and reduce side effects, while others suggest that antioxidants may actually interfere with the effectiveness of chemotherapies.Currently, no clear conclusion can be drawn in this area. There is not enough definitive scientific evidence to discern if melatonin is beneficial against any type of cancer, whether it increases (or decreases) the effectiveness of other cancer therapies, or if it safely reduces chemotherapy side effects.

Chemotherapy side effects

Severalhuman trials have examined the effects of melatonin on side effects associated with various cancer chemotherapies (such as carboplatin, cisplatin, daunorubicin, doxorubicin, epirubicin, etoposide, 5-fluorouracil, gemcitabine, and mitoxantrone). Most of these studies are published by the same research group, and involve giving melatonin through the veins or injected into muscle. Studies have included patients with advanced lung, breast, gastrointestinal, prostate, and head/neck cancers, as well as lymphoma. Promising early results include reductions in nerve injury (neuropathy), mouth sores (stomatitis), wasting (cachexia), and platelet count drops (thrombocytopenia) with various chemotherapy agents. Animal studies note reduced severity of heart damage from anthrocycline drugs or lung damage from bleomycin. Some researchers attribute these reported benefits to antioxidant properties of melatonin. Overall, it remains controversial whether antioxidants increase effectiveness and reduce side effects of chemotherapies, or whether antioxidants actually reduce effectiveness of chemotherapies.Increased platelet counts after melatonin use have been observed in patients with decreased platelets due to cancer therapies (several studies reported by the same author) and stimulation of platelet production (thrombopoeisis) has been suggested but not clearly demonstrated.Although these early reported benefits are promising, high-quality controlled trials are necessary before a clear conclusion can be reached in this area. It remains unclear if melatonin safely reduces side effects of various chemotherapies without altering effectiveness.

Circadian rhythm entraining (in blind persons)

In blind individuals, light and dark stimuli are not received by the eye to trigger melatonin release and the onset of sleep. In these patients, natural melatonin levels peak at a different hour every night to the point where individuals may sleep during the day and awake at night. This is commonly referred to as "free running" circadian rhythm. There are multiple published small case series and case reports in the literature, yet limited controlled trials to date in this population. Present studies and individual cases suggest that melatonin, administered in the evening, may correct circadian rhythm. Large, well-designed controlled trials are needed before a stronger recommendation can be made.

Depression (sleep disturbances)

Depression can be associated with neuroendocrine and sleep abnormalities, such as reduced time before dream sleep (REM latency). Melatonin has been suggested for the improvement of sleep patterns in patients with depression, although research is limited in this area. Further studies are needed before a clear conclusion can be reached.

Glaucoma

It has been theorized that due to effects on photoreceptor renewal in the eye, high doses of melatonin may increase intraocular pressure and the risk of glaucoma, age-related maculopathy and myopia, or retinal damage. However, there is preliminary evidence that melatonin may actually decrease intraocular pressure in the eye, and it has been suggested as a possible therapy for glaucoma. Additional study is necessary in this area. Patients with glaucoma taking melatonin should be monitored by a healthcare professional.

Headache prevention

Several small studies have examined the possible role of melatonin in preventing various forms of headache, including migraine, cluster and tension-type headache (in people who suffer from regular headaches). Limited initial research suggests possible benefits in all three types of headache, although well-designed controlled studies are needed before a firm conclusion can be drawn.

High blood pressure (hypertension)

Several controlled studies in patients with high blood pressure report small reductions in diastolic and systolic blood pressure when taking melatonin by mouth (orally) or inhaled through the nose (intranasally). Most trials have been small and not well designed or reported. Better-designed research is necessary before a firm conclusion can be reached.

HIV / AIDS

There is a lack of well-designed scientific evidence to recommend for or against the use of melatonin as a treatment for AIDS. Melatonin should not be used in place of more proven therapies, and patients with HIV/AIDS are advised to be treated under the supervision of a medical doctor.

Insomnia (of unknown origin in the non-elderly)

There are several small controlled human trials and pilot research of melatonin taken by mouth in people with insomnia. Results have been inconsistent, with some studies reporting benefits on sleep latency and subjective sleep quality, and other research finding no benefits. Most studies have been small and not rigorously designed or reported. Better research is needed before a firm conclusion can be drawn.Notably, several studies in elderly individuals with insomnia provide preliminary evidence of benefits on sleep latency (discussed above).

Parkinson's disease

Due to very limited study to date, a recommendation cannot be made for or against the use of melatonin in Parkinsonism or Parkinson's disease. Better-designed research is needed before a firm conclusion can be reached in this area.

Periodic limb movement disorder

There is very limited study to date for the use of melatonin as a treatment in periodic limb movement disorder. Better-designed research is needed before a recommendation can be made in this area.

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