- Indications with possible efficacy:
Circadian rhythm sleep disorders in blind and in children and adolescents with mental retardation, autism and central nervous system disorders
- Indications with possible, but poorly documented efficacy:
Jet lag (popular use)
Various insomnias (popular use)
- Indications with no proof of efficacy:
Benzodiazepine and nicotine withdrawal
Chronic fatigue syndrome
Insomnia due to shift-work
Irritable bowel syndrome
Migraine and cluster headache prevention
Skin protection from ultraviolet radiation (topically)
Sleep disorders attributed to sleep restriction or altered sleep schedule (popular use)
To enhance the immune system
- Risk of Drug Interactions:
- Adverse Effects:
Where it comes from: pineal gland extracts from certain animal species or synthetically produced.
Melatonin is a naturally occurring hormone of the human body. It is secreted in the brain by the pineal gland and some other tissues. It is believed to regulate the circadian rhythm and sleep by interacting with receptors located in the brain. Light-sensitive receptors located in the eye influence the synthesis and release of this hormone. Melatonin levels increase in darkness and decrease in light. Melatonin may play a role in the control of body temperature, cardiac function and reproductive system.
Melatonin is available as immediate-release or controlled-release tablets.
Direction of use
Insomniacs of all ages and healthy elderly people have reduced circulating melatonin levels. Melatonin may also be used for children.
Used doses: 0.3 to 6 mg at bedtime
Laboratory studies have shown a reduced growth of cancerous tumors when exposed to melatonin. It appears to improve the survival rate of patients in association with radiotherapy, chemotherapy, or interleukin-2. It may also improve thrombocytopenia. However, its exact use in the treatment of cancer remains to be established.
Used doses: 10 to 50 mg at bedtime, to begin 7 days prior to therapy.
- Side effects
Melatonin is not associated with any severe toxicity. There have been reports of headaches, dizziness, nausea, stomach ache, irritability, depressive symptoms and reduced alertness as well as daytime fatigue. Its long-term safety is still not established.
Melatonin is contraindicated in depressive, diabetic and epileptic patients or in case of liver disease.
Because it has sedative properties, melatonin may increase the drowsiness induced by other products such as alcohol, benzodiazepines (Valium, Ativan, etc.), kava, valerian, etc.
Melatonin may also decrease the effectiveness of some drugs used for the treatment of high blood pressure.
Melatonin may affect the immune system and should not be used during immunosuppressive therapy.
Before taking melatonin, check with your pharmacist to make sure that there are not interactions with your regular medication.
- Pregnancy and breastfeeding
Since there is no safety data available concerning its use during pregnancy and breast-feeding, pregnant and lactating women should not take melatonin.
- Melatonin has interesting properties combined with a reassuring adverse effect profile. Clinical information available on melatonin leads us to believe that it may be useful in some indications. However, its long-term safety profile is still unknown.
- Use of natural melatonin from animal pineal gland is controversial and should be avoided due to the possibility of contamination.
In 2004, Canada adopted new regulations that control the manufacturing, packaging, labeling and importing of natural health products. The new regulations also include an adverse reaction reporting system. Products that conform to the regulation's criteria are identified with a natural product number (NPN) and can be legally sold in Canada. This number indicates that the product meets specific criteria for safety and purity, not that it is effective for any indication.
Medicinal plant contents vary naturally from plant to plant - just as fruits from the same package may vary in taste and texture. There is no standard to measure the active content of each plant. Thus, efficacy of natural products should be expected to vary from brand to brand as well as from bottle to bottle of the same brand.
For more information about the Natural Health Products Regulations, or to check if a product has been assessed, visit the Health Canada website at www.hc-sc.gc.ca/dhp-mps/prodnatur/index-eng.php.
- Facts & Comparisons, The Lawrence review of natural products, 1998
- Natural Medicines Comprehensive Database, Therapeutic Research Faculty, online
- Herbal Companion to AHFS DI, American Society of Health-System Pharmacists, 2001
- Lininger S. et Al. The Natural Pharmacy, Prima Health, 1998
- Passeportsanté.net. Mélatonine. www.passeportsante.net
- Rotblatt M. et Ziment I. Evidence-Based Herbal Medicine, Hanley & Belfus, 2002
- Natural Therapeutics Pocket Guide, 2000-2001
- The Review of Natural Products, 6th Edition, 2010
- Health Canada, Natural Products Database