Complementary/Alternative Medicine: This monograph describes a natural or herbal product that is not subject to FDA guidelines for medicines. Patients and clinicians are advised to read package labels carefully to ensure safe and efficacious use.


Trade Name(s)

  • pineal hormone
  • N-acetyl-5–methoxtryptamine

Ther. Class.


Common Uses

Sleep disorders (including insomnia, jet lag and circadian rhythm disorders)


Melatonin is a hormone secreted from the pineal gland in a 24-hour circadian rhythm, regulating the normal sleep/wake cycle. As a supplement, melatonin has both phase-shifting and sleep-promoting properties. In addition to promoting sleep, physiologic roles of melatonin include regulation of the secretion of growth hormone and gonadotropic hormones. It also possesses antioxidant activity.

Therapeutic Effect(s):

Improved sleep pattern.


Absorption: Unknown

Distribution: Unknown

Metabolism and Excretion: Unknown

Half-life: Unknown




Contraindicated in:

  • Hypersensitivity;
  • Pregnancy and lactation.

Use Cautiously in:

  • Seizure disorders;
  • Diabetes;
  • Hypertension.

Adverse Reactions/Side Effects

CV: hypotension

CNS: drowsiness, headache, dizziness

GI: nausea, vomiting, abdominal cramps

* CAPITALS indicate life-threatening.
Underline indicate most frequent.


Natural Drug Interaction

  • Additive sedation with  CNS depressants..
  • May increase bleeding risk with  antiplatelet agents and  anticoagulants..
  • May interfere with the glucose lowering effects of  hypoglycemic agents..
  • May decrease effectiveness of nifedipine..


  • May have additive sedative effects with herbs that have sedative properties including 5–HTP, kava, St.John's wort, valerian and others.
  • May increase risk of bleeding with herbs that have antiplatelet/anticoagulant properties such as clove,  garlic, ginger, gingko, ginseng and others.


PO (Adults): 0.3–10 mg daily at bedtime.


Tablets: 3 mg


  • Assess sleep patterns before and periodically throughout therapy.

Lab Test Considerations:

Monitor blood glucose, coagulation panel, hormone panel, and lipid panel periodically during therapy.

Potential Diagnoses

  • Insomnia (Indications) 


  • PO Administer before bedtime.

Patient/Family Teaching

  • Instruct patient to take at bedtime as directed.
  • Causes drowsiness. Caution patient to avoid driving and other activities requiring alertness until response to medication is known.
  • Caution patient to avoid concurrent use of alcohol or other CNS depressants.
  • Advise female patient to notify health care professional if pregnancy is planned or suspected or if breastfeeding.

Evaluation/Desired Outcomes

Relief of insomnia.

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