- Pineal hormone
For Patients & Caregivers
Melatonin has not been shown to treat cancer in humans.
Melatonin is a hormone naturally produced by the brain in humans. The supplemental form is used to treat insomnia. Scientists believe that it controls circadian rhythms of sleep and wakefulness. Nighttime darkness causes increased production of melatonin, promoting sleep and causing a decrease in body temperature. Both elderly and depressed patients tend to have lower baseline levels of melatonin. Laboratory studies suggest that melatonin is a potent antioxidant that stimulates some aspects of the immune system, but it is not known if this effect occurs in humans. Melatonin also inhibits the growth of certain cancer cells including breast cancer and melanoma when it is directly applied to these cells in laboratory and animals studies. Studies in humans, however, do not show an anticancer effect. When used at the same time as specific chemotherapy drugs, melatonin may increase survival time.
- To prevent or slow progression of Alzheimer’s disease
Clinical trials have had conflicting results.
- To prevent aging
Clinical trials show that melatonin can help age-related sleep problems, but there is no evidence to support its use as an “anti-aging” supplement.
- To treat cancer
Clinical trials do not support this use, but a few studies found that a combination of melatonin with standard chemotherapy may increase survival time in cancer patients.
- To reduce the severity of chemotherapy side effects
In two clinical trials, melatonin did not increase blood cell counts reduced during chemotherapy or radiation therapy. One clinical trial showed that patients treated with melatonin had reduced chemotherapy-associated side effects such as weight loss and low blood platelet counts.
- To treat depression
Clinical trials have found melatonin effective in treating depression associated with fibromyalgia or menopause, but have not found it effective in treating major depression.
- To treat HIV and AIDS
No scientific evidence supports this use.
- To treat insomnia
Several clinical trials support this use.
- To prevent and manage jet lag
Clinical trials yielded mix results.
- To treat seasonal affective disorder (SAD)
Clinical trials have had conflicting results.
- To ease withdrawal from benzodiazepines
Two clinical trials have studied this use, with conflicting results.
- For migraine prevention
One small study suggests melatonin can reduce the frequency of migraine attack.
- This product is regulated by the FDA as a dietary supplement. Unlike approved drugs, supplements are not required to be manufactured under specific standardized conditions. This product may not contain the labeled amount or may be contaminated. In addition, it may not have been tested for safety or effectiveness.
- Melatonin may cause drowsiness. Patients should not drive or operate heavy machinery until familiar with the effects of melatonin.
- Because melatonin can alter levels of estrogen, patients with hormone-sensitive cancers should consult their physicians before considering melatonin supplementation.
For Healthcare Professionals
Melatonin is produced endogenously in humans by the pineal gland. Although the exact mechanism of action is unknown, melatonin is thought to control the circadian pacemaker and promote sleep (1). Small amounts of melatonin are found in fruits, nuts, olive oil and wine. The supplemental form is used as a sleep-aid.
Clinical studies suggest that melatonin may decrease sleep latency and improve sleep duration (2) (3) (4), but randomized trials have produced mixed data (27) (28) (29). No significant effects of melatonin on secondary sleep disorders associated with medical, neurological, or substance abuse disorders were found in a meta-analysis (5). Melatonin may decrease surgery-associated anxiety and pain (6) as well as the frequency of migraine attacks (7). Conclusions from a systematic review indicate that it is effective in reducing perioperative anxiety but its utility as an analgesic remains inconclusive (30).
In vitro and in vivo studies suggest that melatonin has antiproliferative properties and synergistic effects with anticancer agents (8) (9) (32), as well as protective effects against adriamycin-induced cardiotoxicity (33). Clinical trials evaluating melatonin as a monotherapy or in combination with other agents and in patients with solid tumors suggest improvements in quality of life and survival time (10) (11) (12) (13). Other studies yielded conflicting results (35).
Further, in studies of postmenopausal breast cancer survivors, short-term melatonin supplementation did not influence estradiol levels (36) but improved sleep quality (37). However, a case report suggests that use of oral melatonin may delay menopause in premenopausal women by modulating levels of follicle stimulating hormone (FSH) and estrogen (31). Patients with hormone-sensitive cancers should, therefore, consult their physicians before considering melatonin supplementation.
Melatonin is an endogenously produced indolamine hormone secreted by the pineal gland in humans. Nocturnal secretion is regulated by circadian rhythms and nighttime darkness (17), and melatonin is thought to control the circadian pacemaker and promote sleep. Ironically, melatonin is associated with wakefulness and activity in nocturnal animals (14). As levels of melatonin increase, an associated drop in core body temperature occurs. Both elderly and depressed patients tend to have lower basal levels of melatonin (2).
Melatonin appears to be a potent free-radical scavenger (18), interacting with cytosolic calmodulin and stimulating the production of IL-4 in bone marrow T-lymphocytes (1). In vitro and animal studies suggest that antitumor effects may occur through antimitotic or immunomodulatory activity. In vitro studies demonstrate that melatonin has antiproliferative effects on human breast cancer (HS578T) (19) and mouse melanoma (B16BL6, PG19) (8). Melatonin reduces proliferation of PC-3 and LNCaP cells in mice, but has no effect on apoptosis (9). The effect of melatonin on tumor cell growth may be mediated in part by melatonin receptor signaling. (20) (21) In endometrial cancer cells, it interferes with estrogen receptor expression (22).