- Pineal hormone
For Patients & Caregivers
Tell your healthcare providers about any dietary supplements you’re taking, such as herbs, vitamins, minerals, and natural or home remedies. This will help them manage your care and keep you safe.
What is it?
What is it used for?
Melatonin is used to:
- Treat insomnia (trouble sleeping)
- Treat side effects of chemotherapy such as low platelet counts, weakness, and depression
- Keep blood counts from getting low due to radiotherapy
- Treat seasonal affective disorder (SAD)
- Treat migraines
- Treat insomnia in children with autism spectrum disorder
Melatonin also has other uses that haven’t been studied by doctors to see if they work.
Talk with your healthcare provider before taking supplements or higher amounts of melatonin. They can interact with some medications and affect how they work.
For more information, read the “What else do I need to know?” section below.
What are the side effects?
What else do I need to know?
- Avoid melatonin if you’re driving or operating heavy machinery until you’re familiar with how it affects you. It can cause drowsiness.
- Talk with your healthcare provider if you have hormone-sensitive cancer like breast or prostate cancer. Melatonin can change the amount of estrogen in your body. This may worsen your condition.
- Talk with your healthcare provider if you’re taking nifedipine (Procardia®). Using melatonin at the same time can increase your blood pressure and heart rate.
- Talk to your healthcare provider if you’re taking blood thinners such as warfarin (Coumadin®). Melatonin may increase your risk of bleeding.
For Healthcare Professionals
Melatonin is produced endogenously in humans by the pineal gland. Although the exact mechanism of action is unknown, it 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), although randomized trials have produced mixed data (27) (28) (29). A meta-analysis did not find any significant effects with melatonin on secondary sleep disorders associated with medical, neurological, or substance abuse disorders (5), but supplementation was reported to improve subjective sleep quality in patients with traumatic brain injury (44). Additional studies show that melatonin may decrease surgery-associated anxiety and pain (6) as well as frequency of migraine attacks (7). Data also indicate that it can reduce perioperative anxiety (30) (56), but there is insufficient evidence for its use to improve sleep in ICU patients (46), delirium in hospitalized patients (57), to improve depression or depressive symptoms (47), or for seasonal affective disorder (SAD) (48). It also did not improve nocturia in a small study of multiple sclerosis patients (53). A few studies suggest melatonin may be helpful for jet lag (51) (52). Studies on whether melatonin can help in benzodiazepine withdrawal are mixed (49) (50).
Data also suggest benefits of child-appropriate prolonged-release melatonin for long-term treatment in children and adolescents with autism spectrum disorder and insomnia (59). The American Academy of Neurology guidelines recommend using melatonin, starting with a low-dose, for children and adolescents with autism spectrum disorder and sleep disturbance if behavioral strategies have not been helpful, and if contributing coexisting conditions and use of concomitant medications have been addressed (60).
Preclinical studies suggest that melatonin has antioxidant (38) (39) and antiproliferative properties, including against breast cancer cells (40); synergistic effects with anticancer agents (8) (9) (32); and 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), but melatonin did not improve appetite, weight, or quality of life in cancer patients with cachexia (35). In studies of postmenopausal breast cancer survivors, short-term supplementation did not influence estradiol levels (36) but improved sleep quality (37). Data also suggest that melatonin may help reduce incidence of chemotherapy side effects including thrombocytopenia, asthenia, and neurotoxicity (54); cognitive function, sleep quality and depressive symptoms (61); minimize radiotherapy-induced reduction in blood cell counts (58); and protect against radiation-induced genotoxicity (62).
According to a case report, oral melatonin may delay menopause in pre-menopausal women by modulating levels of follicle stimulating hormone (FSH) and estrogen (31).
Mechanism of Action
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, it 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 is a free-radical scavenger (18) (38) and enhances antioxidative enzyme activities (39), interacting with cytosolic calmodulin and stimulating IL-4 production 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 antiproliferative effects on human breast cancer (HS578T) (19) and mouse melanoma (B16BL6, PG19) (8). Decreases in breast cancer metastasis may occur via modulation of Rho-associated kinase protein-1 expression (41). Melatonin reduces proliferation of PC-3 and LNCaP cells in mice, but has no effect on apoptosis (9). Its effect 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). Other laboratory studies suggest that melatonin behaves both as a selective estrogen receptor modulator (SERM) and as an aromatase inhibitor (42) (43). In a murine model, it modulated expression of genes crucial for DNA repair — Ogg1, Apex1, and Xrcc1 — in peripheral blood cells, to reduce X-ray-induced DNA damage (45).
- Drowsiness, alterations in sleep patterns, altered mental status, disorientation, tachycardia, flushing, pruritus, abdominal cramps, headaches, trouble sleeping, bad dreams, hypothermia (1) (2) (14) (15) (36)
- Hypothermia in autism with sleep disorder: In a 3-year-old girl whose body temperature dropped to 34°C following a single dose of melatonin. Supplementation was stopped, but hypothermia continued for 2 more days after which the temperature returned to normal value (63).
Nifedipine: Concomitant administration of melatonin and nifedipine has resulted in elevations in blood pressure and heart rate (16).
CYP1A2 substrates: Melatonin inhibits CYP1A2 and may increase the bioavailability of substrate drugs, like fluvoxamine (23) (26) (34).
Anticoagulants: Oral melatonin intake is associated with lower plasma levels of factor VIII and fibrinogen (25). Therefore, this may increase the risk of adverse effects when used with anticoagulant medications.
Rhubarb: A study using human primary hepatocytes showed that concomitant use can cause metabolic disorder of melatonin (55).