II. Indications
- Sleep onset Insomnia
- Non-24 hour sleep wake disorder (blind patients)
- Delayed Sleep Phase Syndrome (adolescents)
- Jet Lag
- Night Shift Workers with Insomnia (less effective)
III. Physiology
- Pineal gland synthesizes Melatonin
- Overall Pathway: Tryptophan to Serotonin to Melatonin
- May also affect adrenal and gonadal function
- Endogenous Melatonin physiology
- Secreted at night
- Normally highest levels during sleep
- Increases rapidly late evening
- Peaks after midnight
- Decreases in Morning
- Potential Effects on Sleep
- Improved Sleep Efficiency (Sleep Time/Time in bed)
- Decreased Nocturnal Awakenings
- Improved Sleep quality
- Does not Decrease Sleep Latency
- Does not Increase total sleep time
- As compared with Benzodiazepines
- Not addictive
- Does not suppress REM Sleep
- Does not increase morning Sleepiness
- Future Potential uses
- Chemotherapeutic
IV. Pathophysiology
- Elderly with Insomnia
- Low levels of Melatonin
- Blind with irregular sleep cycles
- Free running Melatonin
- Exogenous Melatonin shown to normalize sleep rhythms
- Melatonin 5mg at bedtime for 3 weeks
- References
V. Sources
- Marketed as a dietary supplement
- Not regulated by FDA
- No information on production, purity, manufacturer
- Risk of impurities
- Example: L-Tryptophan related deaths
- Consumers should purchase USP Verified products
VI. Dosing
-
General
- Effective doses are lower than package insert
- May be effective for promoting sleep onset
- Not effective for maintaining sleep (extending sleep duration)
- Does not require tapering
- Dosing by age
- Child (over age 6 months): Start at 1 mg (maximum effective dose 3 mg)
- Teens: Start at 3 mg (maximum dose 5 mg)
- Adult: Start at 3 mg (maximum effective dose 6 mg, absolute maximum 10 mg)
VII. Dosing: Specific Indications in Adults
-
Night Shift Workers
- Start with 3 mg prior to daytime sleep (may increase to 5 mg)
-
Sleep onset Insomnia
- Start with 3 mg at 30 to 60 minutes before bedtime (may increase to 5 mg)
-
Jet Lag
- Melatonin 5 mg orally at bedtime on arrival at destination and for 2-6 nights after arrival
VIII. Efficacy: Jet Lag
- Recent Cochrane review suggests effective at travel
- Indications
- Travel across 5 or more time zones
- May also be useful if 2 or more time zones crossed
- Most effective when traveling eastward
- Protocol
- Take 5 mg PO at bedtime on arrival at destination
- Continue for 2-5 days after arrival
- References
- Indications
- Other small trials show benefit at travel time
- Petrie (1989) Br Med J 298:705
- Before travel: 5 mg PO at bedtime for 3 days
- After travel: 5 mg PO at bedtime for 3 days
- Petrie (1993) Biol Psychiatry 33:526
- After travel: 5 mg PO at bedtime for 5 days
- Claustrat (1992) Biol Psychiatry 32:705
- Before travel: 8 mg PO at bedtime for 1 day
- After travel: 8 mg PO at bedtime for 3 days
- Petrie (1989) Br Med J 298:705
- Trials showing lack of Melatonin benefit in Jet Lag
- Hao (2000) J Clin Endocrinol Metab 85(10):3618-22
IX. Efficacy: Insomnia
- Some small trials suggest benefit
- Garfinkel (1995) Lancet 346:541
- Melatonin 2 mg PO 2 hours before bedtime
- Dollins (1994) Proc Natl Acad Sci 91:1824
- Melatonin 0.3 to 1 mg PO 1-2 hours before bedtime
- Zhadanova (1995) Clin Pharmacol Ther 57:552
- Melatonin 0.3 to 1 mg PO 1-2 hours before bedtime
- Garfinkel (1995) Lancet 346:541
X. Safety
- Not recommended in pregnancy and Lactation due to insufficient safety data
- May effect growth in children on Melatonin longterm (hormonal suppression)
XI. Adverse Effects: Standard dosing
XII. Adverse Effects: Higher doses (e.g. 10 mg, often mixed with other supplements)
- Hangover Sensation
- Lethargy
- Disorientation
- Amnesia
XIII. Myths: False Claims or myths without scientific support
- Anti-Aging effect
- Heart and Immune System Strengthening
- Improved Sexual Libido and Vitality
- Seasonal Affective Disorder treatment
XIV. Drug Interactions
XV. References
- (2023) Presc Lett 30(9): 54
- (2022) Presc Lett 29(3): 17
- Cupp (1997) Am Fam Physician 56(5):1421-1425 [PubMed]