Contributor: Taylor Lynch MD
Educational Pearls:

Melatonin is an endogenous hormone released primarily by the pineal gland
- Also released by extrapineal regions in the retina, the GI tract, and some immune cells
Peak secretion occurs at night and is suppressed during the day
- Secretion and production decrease with age
- Older patients experience the greatest improvement in sleep latency and sleep quality
Mechanism of action in the suprachiasmatic nucleus of the hypothalamus
- MT1 receptor
  - Reduces normal firing
- MT2 receptor
  - Shifts the circadian rhythm
FDA approved for insomnia
- Decreases sleep latency by 7 minutes
- Increases total sleep time by 8 minutes
FDA approved for circadian sleep-wake disorders
- Jet lag
  - Most effective in west-to-east travel
  - Best if crossing at least 5 time zones
- Shift work
  - A study examined ED physicians and nurses with rotating shifts
  - Modest increase in deep sleep percentage
  - No difference in cognition or reaction time the day after taking melatonin
  - Nurses on rotating night shifts experienced increased total sleep time by 20 minutes
Dosing
- 0.5 - 3 mg is the most evidence-based dosing
- Higher doses increase the risk of rebound grogginess but do not improve outcomes

References

Ahmad SB, Ali A, Bilal M, et al. Melatonin and Health: Insights of Melatonin Action, Biological Functions, and Associated Disorders. Cell Mol Neurobiol. 2023;43(6):2437-2458. doi:10.1007/s10571-023-01324-w
Herxheimer A, Petrie KJ. Melatonin for the prevention and treatment of jet lag. Cochrane Database Syst Rev. 2002;(2):CD001520. doi:10.1002/14651858.CD001520
Morgenthaler TI, Lee-Chiong T, Alessi C, Friedman L, Aurora RN, Boehlecke B, Brown T, Chesson AL Jr, Kapur V, Maganti R, Owens J, Pancer J, Swick TJ, Zak R; Standards of Practice Committee of the American Academy of Sleep Medicine. Practice parameters for the clinical evaluation and treatment of circadian rhythm sleep disorders. An American Academy of Sleep Medicine report. Sleep. 2007 Nov;30(11):1445-59. doi: 10.1093/sleep/30.11.1445. Erratum in: Sleep. 2008 Jul 1;31(7):table of contents. PMID: 18041479; PMCID: PMC2082098.
Thottakam BMVJ, Webster NR, Allen L, Columb MO, Galley HF. Melatonin Is a Feasible, Safe, and Acceptable Intervention in Doctors and Nurses Working Nightshifts: The MIDNIGHT Trial. Front Psychiatry. 2020;11:872. Published 2020 Aug 27. doi:10.3389/fpsyt.2020.00872

Summarized and edited by Jorge Chalit, OMS4

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Podcast 995: Melatonin

Emergency Medical Minute