Melatonin
hormone
Key Takeaways
- Meta-analysis of 23 RCTs found significant sleep quality improvement (pmid:33417003)
- Emerging evidence for CVD risk reduction and immune modulation (pmid:36480969, pmid:36235587)
- Parallels to vitamin D as a darkness-deficiency marker (pmid:36235587)
- Efficacy confirmed in dietary supplement meta-analysis (pmid:33441476)
- No FDA daily value; endogenous hormone
Evidence Spectrum
15 studies reviewed →15
Studies Reviewed
fat-soluble
Solubility
Role in the Body
Melatonin is produced by the pineal gland in response to darkness, regulating circadian rhythm and sleep-wake cycles. Synthesized from tryptophan via 5-HTP and serotonin, it also functions as a potent antioxidant, immune modulator, and mitochondrial regulator. MT1 and MT2 receptors are distributed throughout the body, indicating roles in immune modulation, cardiovascular function, and GI protection.
- Circadian rhythm regulation
- Antioxidant activity
- Immune modulation
- Mitochondrial function regulation
- GI protective effects via brain-gut axis
Supplement Forms
Synthetic melatonin
RecommendedBioavailability: 0%
Most common; identical to endogenous form. Immediate and extended-release available.
Phytomelatonin
Bioavailability: 0%
Plant-derived; less studied (pmid:36235587)
Animal-derived
Bioavailability: 0%
Contamination risk; not recommended
Food Sources
Tart cherries
Walnuts
Tomatoes
Grapes
Rice
Barley
Kiwifruit
Deficiency
Prevalence: Not a classical deficiency. Production declines with age and is suppressed by artificial light.
Symptoms:
- Insomnia
- Circadian disruption
- Increased oxidative stress
Risk Factors:
- Aging
- Blue light exposure at night
- Shift work
- Beta-blockers, NSAIDs
Safety & Interactions
Possible Side Effects:
- • Daytime drowsiness
- • Headache
- • Dizziness
- • Nausea
- • Vivid dreams
Drug Interactions:
- • Increased bleeding risk with anticoagulants (pmid:36304597)
- • Additive sedation with CNS depressants
- • Blood pressure effects
- • Immunosuppressant interactions
Contraindications:
- • Children (requires medical supervision)
- • Autoimmune conditions
- • Pregnancy/breastfeeding
Frequently Asked Questions
What dose of melatonin for sleep?
0.5-5 mg, 30-60 minutes before bed. Start with the lowest effective dose.
Is long-term melatonin use safe?
Short-term appears safe. Long-term data are limited. Consult a healthcare provider.
Is melatonin only for sleep?
Also functions as an antioxidant, immune modulator, and mitochondrial regulator.
Research Sources
15 peer-reviewed studies analyzed from PubMed. 8 directly cited in this review.