What is Melatonin and How Does it Work?
Melatonin is a naturally-produced hormone in the body that plays an important role in the sleep-wake cycle. The pineal gland primarily synthesizes the hormone in the brain. The hormone is released in response to darkness, and it gets suppressed by light.(1, 2, 3, 4) As the sun goes down and darkness starts to increase, the brain signals the pineal gland to start the secretion of melatonin. This typically happens after 9 p.m. it is the increased levels of melatonin in the bloodstream that sends signals to the brain to become less alert and start feeling sleepy. The secretion of melatonin peaks in the middle of the night (between 2 to 4 a.m.) and then gradually reduces during the second half of the night. Almost 80 percent of melatonin gets synthesized at night. The action of melatonin inhibits the signals in the brain that promote wakefulness, which helps promote sleep by making a person feel drowsy or tired as it gets closer to bedtime.(5, 6, 7)
The production and secretion of melatonin again start to decrease in response to the sunlight. This makes you alert and wakes you up in the morning. However, for people who have sleeping problems, the hormone melatonin is available as a sleeping aid supplement in the form of liquids, pills, and chewable tablets.
Due to melatonin’s sleep-promoting effects, melatonin supplements are used for the treatment of a variety of sleep problems, including:
- Jet lag(8)
- Delayed sleep-wake phase disorder(10)
- Shift work sleep disorder(11)
- Sleeping problems in children with attention deficit hyperactivity disorder (ADHD) or autism(12)
What is a Safe Dose of Melatonin?
It is important to keep in mind that the US Food and Drug Administration (FDA) does not regulate melatonin as a drug. Due to this, there is not much information available on what is the safe and optimal dosage of melatonin. In fact, the dosage of melatonin supplements that have been used in previous scientific studies also varies widely – from using 0.1 to 10 milligrams (mg).(13) A review in 2017 defined that a general dosage of melatonin should be between 1 and 5 milligrams.(14)
Melatonin takes around one to two hours to work, so it is best to take the supplement at least two hours before bedtime.(15)
Melatonin Dosage for Older Adults
The amount of melatonin produced by the body starts to decrease with age. Due to this, melatonin supplements have been found to help older adults who have trouble falling asleep.(16)
Three is still a lot of debate about what is the optimal dosage of melatonin for older adults. A review from 2016 of sleeping aids for older adults recommends a dosage of 1 to 2 milligrams of immediate-release melatonin taken one hour before bedtime.(17)
Melatonin Dosage for Children
Just like melatonin supplements for adults, there is not much data available for what is the safe and optimal dosage of melatonin for children. The dosage of melatonin for children also depends on the child’s age. A 2016 review recommends the following age-based dosages of melatonin to be taken 30 to 60 minutes before bedtime:(18)
- 1 milligram for infants
- 2.5 to 3 milligrams for older children
- 5 milligrams for adolescents
Since there are no clear dosage guidelines with regards to melatonin supplements for children, it is necessary to consult your child’s pediatrician before you start giving melatonin to your child.
The Food and Drug Administration classifies melatonin to be a dietary supplement. This means that it is not as strictly regulated as a regular drug. For the regulation of dietary supplements, label claims and product safety do not need to meet the FDA’s approval before being sold.
However, a study carried out in 2017 found that out of 31 different melatonin supplements tested, the actual melatonin content of 71 percent of the products did not match the claim put on the product label. Furthermore, 26 percent of the products also contained serotonin, which can potentially be harmful even in smaller doses.(19)
When you are out to buy melatonin supplements, it is a good idea to search for products that are ‘USP verified.’ USP (United States Pharmacopeia) is an independent organization that ensures that dietary supplements follow proper quality control and dosing guidelines.(20)
Is It Safe To Take Melatonin Supplements Every Night?
According to research by the National Center for Complementary and Integrative Health (NCCIH), short-term use of melatonin supplements appears to be safe for most children and adults. However, there is limited information available on the effects of taking melatonin supplements in the long term.(21)
A study carried out by the University of Copenhagen indicated that long-term melatonin use in adults may cause certain mild side effects when compared to a placebo.(22) Again, studies that looked into the effects of long-term melatonin use in children remain limited.
Since melatonin levels start to naturally decrease at the start of puberty, there are some concerns that long-term melatonin use in children may delay the onset of puberty. However, more research is needed to establish anything conclusively.(23)
What If You End Up Taking Too Much Melatonin?
While melatonin is generally considered to be safe, some mild side effects can happen, especially if you end up taking higher doses or the extended-release formulations of the supplement.(24)
Some of the side effects of melatonin may include:
- Feeling sleepy or drowsy
- Increased urination or bedwetting in children
Some of the less common side effects of melatonin may include:
- Mild tremors
- Abdominal cramps
- Confusion or disorientation
- Feelings of depression
- Low blood pressure (hypotension)
If you experience any side effects from taking melatonin supplements, you should immediately stop taking them and consult your doctor. Your doctor may recommend switching to a lower dose or may put you on an alternative sleeping aid or medication.
Can You Take More Than One Dose In The Same Night?
Many people often find that they are still unable to fall asleep after taking one dose of melatonin. So is it okay to take another dose? Even though it is unlikely that taking an extra dose will cause any harm, but it does increase the risk of experiencing the unwanted side effects of melatonin.(25)
If you find that melatonin supplements are not helping you fall asleep, you should just stop using them and ask your doctor for different medications or strategies to help you get a good night’s sleep.
Who should not take Melatonin?
There is limited research to show how safe it is to use melatonin supplements during pregnancy. At the same time, there is little research to show the effects of taking melatonin supplements while breastfeeding, even though melatonin is a natural component of breast milk.
Due to this, it is perhaps best to avoid taking melatonin if you are pregnant, or breastfeeding, or even if you are planning to become pregnant.
You should also consult your doctor before using melatonin if you have the following medical conditions:
- Kidney disease
- Liver disease
- An autoimmune condition
- You have previously had an allergic reaction to melatonin
Melatonin supplements are widely used to help promote sleep. Since there is not much research or data on what the standard dosage of melatonin supplements is, you should discuss with your doctor about how much melatonin you should take and when. Melatonin is usually considered safe to be taken for the short-term, but there are limited studies to show the long-term effects. At the same time, melatonin supplements are generally considered to be safe, and there are very mild side effects.
If you are taking melatonin and find that it is not helping you fall asleep or experiencing unwanted side effects, you should stop taking it and consult your doctor. Your doctor can recommend other medications or strategies to help you sleep at night.
- Hardeland, R., Pandi-Perumal, S.R. and Cardinali, D.P., 2006. Melatonin. The international journal of biochemistry & cell biology, 38(3), pp.313-316.
- Brzezinski, A., 1997. Melatonin in humans. New England journal of medicine, 336(3), pp.186-195.
- Maestroni, G.J., 1993. The immunoneuroendocrine role of melatonin. Journal of pineal research, 14(1), pp.1-10.
- Reiter, R.J., 2003. Melatonin: clinical relevance. Best practice & research clinical endocrinology & metabolism, 17(2), pp.273-285.
- Dawson, D. and Encel, N., 1993. Melatonin and sleep in humans. Journal of pineal research, 15(1), pp.1-12.
- Wright Jr, K.P., Gronfier, C., Duffy, J.F. and Czeisler, C.A., 2005. Intrinsic period and light intensity determine the phase relationship between melatonin and sleep in humans. Journal of biological rhythms, 20(2), pp.168-177.
- Dijk, D.J. and Cajochen, C., 1997. Melatonin and the circadian regulation of sleep initiation, consolidation, structure, and the sleep EEG. Journal of biological rhythms, 12(6), pp.627-635.
- Herxheimer, A. and Petrie, K.J., 2002. Melatonin for the prevention and treatment of jet lag. Cochrane Database of Systematic Reviews, (2).
- Ellis, C.M., Lemmens, G. and Parkes, J.D., 1996. Melatonin and insomnia. Journal of sleep research, 5(1), pp.61-65.
- van Geijlswijk, I.M., Korzilius, H.P. and Smits, M.G., 2010. The use of exogenous melatonin in delayed sleep phase disorder: a meta-analysis. Sleep, 33(12), pp.1605-1614. Arendt, J., Skene, D.J., Middleton, B., Lockley, S.W. and Deacon, S., 1997. Efficacy of melatonin treatment in jet lag, shift work, and blindness. Journal of biological rhythms, 12(6), pp.604-617.
- Weiss, M.D., Wasdell, M.B., Bomben, M.M., Rea, K.J. and Freeman, R.D., 2006. Sleep hygiene and melatonin treatment for children and adolescents with ADHD and initial insomnia. Journal of the American Academy of Child & Adolescent Psychiatry, 45(5), pp.512-519.
- Savage, R.A., Zafar, N., Yohannan, S. and Miller, J.M.M., 2018. Melatonin.
- Tordjman, S., Chokron, S., Delorme, R., Charrier, A., Bellissant, E., Jaafari, N. and Fougerou, C., 2017. Melatonin: pharmacology, functions and therapeutic benefits. Current neuropharmacology, 15(3), pp.434-443.
- nhs.uk. 2022. Melatonin: a manmade hormone used for short-term sleep problems. [online] Available at: <https://www.nhs.uk/medicines/melatonin/> [Accessed 13 January 2022].
- Vural, E.M., Van Munster, B.C. and De Rooij, S.E., 2014. Optimal dosages for melatonin supplementation therapy in older adults: a systematic review of current literature. Drugs & aging, 31(6), pp.441-451.
- Schroeck, J.L., Ford, J., Conway, E.L., Kurtzhalts, K.E., Gee, M.E., Vollmer, K.A. and Mergenhagen, K.A., 2016. Review of safety and efficacy of sleep medicines in older adults. Clinical therapeutics, 38(11), pp.2340-2372.
- Janjua, I. and Goldman, R.D., 2016. Sleep-related melatonin use in healthy children. Canadian Family Physician, 62(4), pp.315-316.
- Erland, L.A. and Saxena, P.K., 2017. Melatonin natural health products and supplements: presence of serotonin and significant variability of melatonin content. Journal of Clinical Sleep Medicine, 13(2), pp.275-281.
- Usp.org. 2022. Dietary Supplement Manufacturing – USP Verified Mark | USP. [online] Available at: <https://www.usp.org/verification-services/verified-mark> [Accessed 13 January 2022].
- 2022. [online] Available at: <https://www.nccih.nih.gov/health/melatonin-what-you-need-to-know> [Accessed 13 January 2022].
- Andersen, L.P.H., Gögenur, I., Rosenberg, J. and Reiter, R.J., 2016. The safety of melatonin in humans. Clinical drug investigation, 36(3), pp.169-175.
- Boafo, A., Greenham, S., Alenezi, S., Robillard, R., Pajer, K., Tavakoli, P. and De Koninck, J., 2019. Could long-term administration of melatonin to prepubertal children affect timing of puberty? A clinician’s perspective. Nature and science of sleep, 11, p.1.
- Guardiola-Lemaitre, B., 1997. Toxicology of melatonin. Journal of biological rhythms, 12(6), pp.697-706.
- Cleveland Clinic. 2022. How Much Melatonin Should You Take?. [online] Available at: <https://health.clevelandclinic.org/melatonin-how-much-should-i-take-for-a-good-nights-rest/> [Accessed 13 January 2022].
- Can Melatonin Induce Sleep?
- How Effective is Melatonin Supplement, Know its Dosage, Side Effects
- Mechanism of Action of Melatonin, Its Usage and Side Effects
- Does Melatonin Help Anxiety & What Vitamins Are Good For Calming Nerves?
- Melatonin in Epilepsy