Sleep is a basic human need, like food and water, and getting enough sleep is essential for the daily functioning of a healthy human being.

Studies have shown that lack of adequate sleep has been linked to several chronic health problems, such as heart disease, high blood pressure, diabetes, obesity, and even depression.

To get that good night’s sleep regularly, taking melatonin supplements has been proven helpful.

Melatonin is a hormone secreted by the pineal gland into the blood circulation and is involved in controlling an individual’s sleep–wake cycle.

In this article, let us discuss how taking synthesized melatonin as a supplement can improve sleep quality.

What is Melatonin?

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Melatonin is the main hormone secreted by the pineal gland. The pineal gland is a small endocrine organ located at the base of the brain. Melatonin is mainly synthesized by the pineal gland cells from the amino acid tryptophan. 

Tryptophan is converted into serotonin and then ultimately transformed into melatonin by key enzymes along the process. Once synthesized, melatonin is quickly released into the bloodstream to reach target tissues and bind to its receptors, and exert its effects. [1][2][3]

Scientists have long established that melatonin synthesis and secretion are enhanced by darkness and inhibited by light. At sunset, its secretion begins and peaks in the middle of the night. 

By the second half of the night until sunrise, the production and secretion gradually decrease. It has been detected in the blood circulation that 80% of the melatonin is synthesized at night and that during daylight hours, serum concentrations are low. [4]

The best-known purpose of melatonin is to promote sleep. Melatonin regulates the body’s sleep-wake cycles in an individual by promoting sleep while inhibiting wake-promoting signals simultaneously.

After being released from the pineal gland, melatonin interacts with its partner receptors located at designated brain areas responsible for inducing sleep. [5][6]

Indications for Melatonin

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Synthetic melatonin is a dietary supplement that is not FDA-approved to treat conditions associated with sleep deprivation. 

However, there are a few FDA-approved melatonin derivatives that are being sold in the market for the treatment of insomnia. Currently, supplements made from melatonin derivatives are recommended for the treatment of insomnia and other conditions listed below [7][8][9]:

  • Jet lag disorder
  • Shift work sleep disorder
  • Post-traumatic brain injury
  • Neurodegenerative disorders

How To Take Melatonin?

Oral melatonin supplements are produced in different preparations and formulations depending on the manufacturing company.

It can take the form of a tablet, capsule, or liquid and may be formulated as an immediate-release, extended-release, or a combination of both. For tablets and capsules, available dosages being sold in the market today range from 0.1mg to 10mg.

It is worth repeating that melatonin supplements, although presumed safe, are not regulated by the FDA hence effective dosing is not well-defined. As per current FDA guidelines, the usual dose of 0.2mg to 5mg per day taken at least 30 mins up to 2 hours before bedtime is deemed safe. [2][10]

How Long Does It Take for Melatonin to Start Working?

The time it takes for a person to fall asleep after taking melatonin largely depends on the formulation that was ingested.

The immediate-release formulation has been proven to be more effective in inducing the acute sleep-promoting effects of melatonin compared to its extended or controlled-release counterpart. 

It can be used 30 minutes before sleeping time to achieve its desired effect because of its relatively faster tablet disintegration rate. Extended-release formulations mimic the properties and activity of the body’s naturally-produced melatonin and are considered more effective for sleep maintenance. [11][12][13]

The dose does not appear to affect the onset of the sleep-promoting effects of melatonin. Hence, taking a 10mg dose will not make you sleep any faster than taking a 0.2mg tablet; however, it may help you sleep longer. 

Source: Canva

After oral administration of melatonin supplements, its concentration in the bloodstream rises to a peak within an hour. It then gradually diminishes to half of its original amount after 20 minutes to 2 hours, depending on the formulation, dose, and metabolic capacity of the liver. 

Intake of a usual dose such as 1 to 5 mg results in a melatonin blood concentration of 10 to 100 times higher than the physiological peak during nighttime within the hour after ingestion. Melatonin will wear off and return to basal concentrations in 4 to 8 hours. [14]

Melatonin Adverse Effects

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Melatonin as a dietary supplement is considered relatively non-toxic. No evidence also suggests that people develop tolerance to melatonin. 

However, there are still adverse effects that have been reported with higher doses and extended-release formulations. The FDA emphasized that the adverse events were not serious and were consistent with the known safety profile of melatonin [10] these include:

  • Daytime sleepiness
  • Headaches
  • Other sleep-related adverse effects
  • Dizziness
  • Hypothermia
  • Decreased appetite
  • Restlessness
  • Fatigue
  • Hyperactivity

Melatonin Precautions

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Because of the lack of regulations by the FDA, there is insufficient evidence of safety for pregnant and breastfeeding women regarding melatonin intake. Patients taking benzodiazepines should also avoid melatonin because it can lead to excessive sedation when taken together. 

People with kidney and liver problems are not recommended to take large doses of melatonin because their metabolism and clearance mechanisms are impaired, which can lead to the accumulation of melatonin in the body. [12]

A few studies have mentioned melatonin supplements worsened symptoms of depression. For people diagnosed with depression, it is best to consult a professional before using melatonin supplements. Substances such as caffeine, tobacco, and alcohol can also interfere with the effects of melatonin because all three lower melatonin levels in the body.


Synthesized melatonin, although not FDA-approved, is a generally safe option for individuals with sleep deficiency.

The formulation has a more significant effect on improving the overall quality of sleep than dosing. Its immediate-release formulation has been shown to shorten sleep onset, while its extended-release version is better for sleep maintenance. 


Yes, taking melatonin supplements every night for 2  months is okay if you take the right dose deemed safe as recommended by the US FDA and if the supplement is taken at the right time.
Melatonin can relieve the sleep deprivation caused by jet lag for people who travel across two or more time zones. Adults may take a dose of 0.5 to 5 mg orally at bedtime. 

For those traveling eastbound, take melatonin before the flight. An early evening dose is followed by bedtime dosing for 4 days. For westbound travelers, start taking melatonin supplements at bedtime for 4 days when in the new time zone.
Experts suggest working with the sleep-inducing melatonin signals by creating optimal conditions for it to do its job. It is best to keep the lights low and avoid using electronic devices before bedtime because the blue and green light they emit neutralizes the effects of melatonin.

Disclaimer: This article is only a guide. It does not substitute the advice given by your healthcare professional. Before making any health-related decision, consult your healthcare professional.

Editorial References And Fact-Checking

  1. Hardeland, R. (2020) Melatonin. Encyclopedia of Biomedical Gerontology. PP 414-423.
  2. University of Rochester Medical Center. 2023. Melatonin. <>
  3. Tordjman, S., Chokron, S., Delorme, R., Charrier, A., Bellissant, E., Jaafari, N., & Fougerou, C. (2017). Melatonin: Pharmacology, Functions and Therapeutic Benefits. Current neuropharmacology, 15(3), 434–443.
  4. Karasek, M., & Winczyk, K. (2006). Melatonin in humans. Journal of physiology and pharmacology : an official journal of the Polish Physiological Society, 57 Suppl 5, 19–39.
  5. Pandi-Perumal, S. R., Trakht, I., Srinivasan, V., Spence, D. W., Maestroni, G. J., Zisapel, N., & Cardinali, D. P. (2008). Physiological effects of melatonin: role of melatonin receptors and signal transduction pathways. Progress in neurobiology, 85(3), 335–353.
  6. Kapalka, G. 2010. Melatonin. Substances Involved in Neurotransmission. Nutritional and Herbal Therapies for Children and Adolescents. CH 4. PP 71-99.
  7. Ferracioli-Oda, E., Qawasmi, A., & Bloch, M. H. (2013). Meta-analysis: melatonin for the treatment of primary sleep disorders. PloS one, 8(5), e63773.
  8. Posadzki, P. P., Bajpai, R., Kyaw, B. M., Roberts, N. J., Brzezinski, A., Christopoulos, G. I., Divakar, U., Bajpai, S., Soljak, M., Dunleavy, G., Jarbrink, K., Nang, E. E. K., Soh, C. K., & Car, J. (2018). Melatonin and health: an umbrella review of health outcomes and biological mechanisms of action. BMC medicine, 16(1), 18.
  9. Herxheimer, A., & Petrie, K. J. (2002). Melatonin for the prevention and treatment of jet lag. The Cochrane database of systematic reviews, (2), CD001520.
  10. U.S. Food and Drug Administration. 2021. Melatonin. Pharmacy Compounding Advisory Committee Meeting.
  11. Mantle, D. et. al. (2020) Efficacy and safety of supplemental melatonin for delayed sleep–wake phase disorder in children: an overview. Sleep Medicine: X. Vol 2.
  12. Savage RA, Zafar N, Yohannan S, et al. Melatonin. [Updated 2022 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from:
  13. Quera-Salva, M. et al., (2018) Melatonin: Physiological and pharmacological aspects related to sleep: The interest of a prolonged-release formulation (Circadin ® ) in insomnia. Brain. Vol 44. Issue 6. PP 548-557.
  14. Claustrat, B., Brun, J., & Chazot, G. (2005). The basic physiology and pathophysiology of melatonin. Sleep medicine reviews, 9(1), 11–24.


  • Dr. Kara Marcella Barro, M.D.

    Dr. Kara Marcella Barro is a licensed physician who has been serving as a General Practitioner at her local health center. She has devoted her skills and knowledge as a public health doctor to serve the poor and marginalized. At the same time, she is also an educator who passionately promotes preventive medicine through her lectures and writing in the hopes of a better health outcome for everyone. LinkedIn


Dr. Kara Marcella Barro is a licensed physician who has been serving as a General Practitioner at her local health center. She has devoted her skills and knowledge as a public health doctor to serve the poor and marginalized. At the same time, she is also an educator who passionately promotes preventive medicine through her lectures and writing in the hopes of a better health outcome for everyone. LinkedIn