1. Ada
  2. Melatonin

Melatonin

  1. What is melatonin?
  2. How is it produced and controlled?
  3. Supplements
  4. When not to take melatonin supplements
  5. How to take melatonin
  6. Side-effects
  7. Melatonin FAQs

What is melatonin?

Melatonin is a natural hormone which plays an important role in regulating the body’s circadian rhythm, otherwise known as the sleep/wake cycle.[1]

Melatonin helps to promote sleep at night and wakefulness during the day. The hormone’s function has led it to be nicknamed the sleep hormone.

Melatonin supplements are used by people experiencing a wide variety of different problems, which may be associated with insomnia or a disrupted sleep cycle, including jet-lag and headaches.[2] (See the section on supplements for more information.)

The supplements are associated with certain side-effects, which may include stomach cramps and drowsiness during the day. Nevertheless, they are considered to be generally safe for short-term use in most cases, provided that a doctor has been consulted prior to taking them.

Long-term use of melatonin is not generally recommended. People suffering from sleep-related disorders, which are not treated effectively after a short course of melatonin supplementation is prescribed, should seek further medical evaluation, so that the root cause of the problem can be identified and an alternative treatment started.

How is melatonin produced and controlled?

The majority of natural melatonin is produced in the pineal gland of the brain, though smaller quantities are also made in other tissues of the body.[3] Melatonin produced in the brain is released into the bloodstream and circulates throughout the body, where its presence is detected by receptors. These receptors then signal to the body that it is time to sleep.[4]

When is melatonin produced and released by the body?

Natural melatonin production is at its highest at night, typically between the hours of 11pm and 3am, dropping off significantly during the day. It is released into the bloodstream from the brain as soon as it is produced and is carried to all areas of the body by circulation.[4]

Melatonin production is also affected by the seasons, with the hormone being produced earlier in the darker winter months and later in the summer.

How is melatonin made in the body?

The production of melatonin is controlled by the circadian clock, which is located in the suprachiasmatic nuclei region of the brain. This is a tiny region of the brain in the hypothalamus, itself a small region of the brain that performs a variety of important functions, including regulating the body’s temperature and sensations of hunger. The hypothalamus is situated directly above the optic nerves. The suprachiasmatic nuclei region is connected to the pineal gland through the nervous system.[5]

The circadian clock is regulated primarily by light received through the eyes, which tells it when and when not to signal for melatonin production. The circadian clock conveys to the rest of the body whether it is light or dark outside, information which accordingly sets off various functional processes, including the body’s sleep-wake timing, blood pressure regulation, reproductive cycle and core temperature regulation.

The body’s natural production of melatonin occurs when it is dark.[1] Accordingly, melatonin levels typically begin increasing in the late evening, and maximum melatonin levels are usually reached between 2am and 4am. Levels of melatonin decline slowly thereafter, becoming barely detectable in the daytime. This cycle repeats every day; the body’s rhythm is kept to an approximate 24-hour cycle by the circadian clock, which roughly correlates with the light/dark cycle of nature.

What are melatonin supplements used for?

Melatonin is also available as a supplement, typically as a capsule. Supplements of melatonin may be able to help reset the body’s circadian rhythm and bring on feelings of tiredness. Melatonin supplements may be prescribed for some people experiencing:[6][7]

  • Insomnia or jet-lag
  • Benzodiazepine withdrawal, facilitating a calmer tolerance of the withdrawal period
  • Nicotine withdrawal, to ease cravings during the withdrawal period
  • Cancer adjuvant care, as part of a care-plan alongside treatment for cancer[8]
  • Headaches, as a possible preventative medication
  • Shift-work disorder
  • Sleep disorders in adults and children
  • Thrombocytopenia, which may be caused by chemotherapy
  • Winter depression, also known as seasonal affective disorder

If you are experiencing difficulties falling asleep and wish to identify the cause, you can try a free symptom assessment using the Ada app.

Good to know: Melatonin supplements have many different possible uses, and the body of research into their efficacy for treating a variety of different conditions continues to expand. However, because most research into the effects of melatonin supplementation on humans is fairly recent, it is not always possible to have a full understanding of its safety or efficacy in treating a given population group or condition.[9]

Using melatonin to reset the circadian rhythm

Taken as a supplement, synthetic melatonin mimics the effects of the naturally-produced version of the hormone. Supplementary melatonin is principally used by those experiencing insomnia, those with jet-lag and those with delayed sleep phase syndrome, i.e. when the circadian rhythm is out of sync with the day/night cycle.

It is important to note that the use of melatonin supplements does not guarantee the ability to sleep, and that a healthcare professional should always be consulted before beginning use.[10]

Good to know: Melatonin will not be prescribed to treat insomnia if a different treatable cause can be identified. In all cases, where a medical, mental or environmental cause for insomnia is discerned, the causal issue(s) will be addressed as a first-line treatment.

When not to take melatonin supplements

Melatonin supplements are not suitable for people who:[10]

  • Are pregnant or breastfeeding
  • Have a chronic condition affecting the immune system, such as HIV
  • Are affected by seizures
  • Are affected by depression

A doctor should always be consulted before taking melatonin supplements.

In particular, melatonin should not be used without medical guidance by people who are affected by:

People using melatonin should stop if the supplement does not work after a week or two of use. Generally, melatonin supplementation should be considered a possible short-term rather than a long-term solution to problems with sleep. People experiencing recurrent or severe sleeping disorders should seek the advice of a doctor, who will be able to present other therapeutic options in the event that melatonin supplementation is unsuitable or does not provide relief.

Melatonin supplements: drug interactions

Melatonin may interact with other medications. For this reason, it is always recommended that a person check with their doctor before using melatonin supplements at the same time as taking other medications.

In particular, a person should be closely monitored in case of drug interactions if they are using medications, including:[10]

  • Anticoagulant (anti blood-clotting) medication
  • Concurrent immunosuppressive treatment
  • Any medication used on a chronic (long-term) basis

How to take melatonin

In the US, melatonin is available without a prescription from many pharmacies and health food stores. In the EU, a doctor’s prescription will be required in all cases. Elsewhere, a doctor’s prescription may also be required to ensure that the supplement is safe for the person to use and to diagnose any possible underlying conditions that are causing sleep problems.

Melatonin dosage

Before taking melatonin, always refer to the medication packaging or doctor's prescription for exact dosing guidelines in each case. The appropriate dosing regimen can vary between products and situations.

Melatonin for kids

Children and toddlers may be prescribed melatonin supplements for sleep regulation in a variety of situations, including:[11][12]

  • To treat insomnia and to help orchestrate regular bedtimes
  • In cases of autism, a condition in which establishing regular sleeping patterns is a common complication
  • In cases of attention-deficit hyperactivity disorder (ADHD), in which establishing regular sleep patterns is, likewise, a common complication
  • In older children and teenagers, to treat delayed sleep phase syndrome, in which the typical time at which someone is able to fall asleep naturally is several hours later than desired; however, the appropriate dose and duration of a course of melatonin supplementation for teenagers is not known[13]
  • To treat conditions which cause distracting physical discomfort, such as itching, which can prevent a child from falling asleep, for example, atopic dermatitis
  • To establish regular sleeping habits in cases of visual impairment, if a child’s natural production of melatonin is considered to be compromised by having a reduced ability to detect light and dark

Good to know: Despite being prescribed relatively widely to children with impaired vision, there is currently insufficient data to confirm that melatonin supplements are actually effective in these cases.[14]

Always consult a doctor before giving a child melatonin supplements, in order to establish that they are suitable in each case and to ascertain the correct type and dose. This can vary greatly between different children. Melatonin supplements will usually be considered as a treatment for difficulties with sleeping only when other non-medical approaches, such as adjusting the child’s bedtime routine, have proven ineffective.

Babies should only ever be given melatonin under the supervision of a pediatric specialist.

Types of melatonin supplements

Melatonin supplements can contain:

Natural melatonin, which is extracted from the pineal gland of animals Synthetic or man-made melatonin, which is chemically synthesized in a laboratory

Supplements of melatonin generally contain synthetic melatonin, which is safer to use. Natural melatonin may contain harmful pathogens from animals, such as bacteria and viruses, so it is important to always check the instructions on the packet to ensure that the melatonin used is synthetic.

Melatonin supplement products can come in many different forms, including:

Pills for example, tablets or capsules Gummies, which are soft, chewable and flavored Liquid solutions, dispensed with a dropper

Melatonin supplement pills or gummies can function in two ways:

Prolonged-release melatonin supplements release the active ingredient over a number of hours, replicating the timeframe in which the body would naturally release melatonin over the course of the night Instant-release melatonin supplements release the entirety of their active ingredients at once, inducing sleep more quickly than the body might naturally do using its own resources of melatonin

Good to know: Crushing or breaking prolonged-release melatonin supplement products will result in them being absorbed faster by the body than if they had been swallowed whole; this compromises their prolonged-release mechanism.[15]

Doctors can help recommend appropriate melatonin products at the right strength for each person, depending on their specific needs.

When to take melatonin

It is generally recommended that melatonin should be taken one or two hours before bed, though some people will experience a wave of tiredness roughly 20 minutes after taking it. If used to combat jet-lag, the supplement should be taken close to bedtime at the destination.

Taking melatonin supplements during the day is not generally recommended.[16] However, it may help people who need to be awake at night, for example, shift-workers, to sleep during the day. It is important to note that sleeping during the day on a regular basis disrupts the natural circadian rhythm, and taking melatonin supplements in order to facilitate this can lead to greater disruptions to a person’s circadian rhythm in the longer-term.

Long-term use of melatonin supplements

At present, there has not been much research into the safety of using melatonin supplements in the long-term. Therefore, using them for periods of more than four weeks at a time is not recommended.[2]

Melatonin side-effects

Melatonin is generally described as safe when taken in the short-term. Despite this, the advice of a doctor should always be sought before beginning to use the supplement.

Possible side-effects of taking melatonin supplements may include:[17]

  • Drowsiness during the day (daytime fatigue): always follow the instructions on the supplement packet, which may recommend avoiding activities such as driving or operating machinery for a certain number of hours after taking melatonin
  • Stomach cramps, or abdominal pain
  • Decreased alertness
  • Irritability or feelings of depression (transient)
  • Dysphoria ‒ a particularly acute feeling of dissatisfaction with life ‒ in patients who are already depressed
  • Headache
  • Dizziness

Immediate medical attention should be sought if any of the following occur, as they may be signs of an allergic reaction:

  • Difficulty breathing
  • Hives
  • Swelling of the face, lips, tongue or throat

Other signs that a person may require medical attention include:

  • Persistent dysphoria
  • Unresponsiveness to stimuli, such as light, sounds and being spoken to

Melatonin FAQs

Q: Are melatonin supplements safe for children?
A: Yes, in specific cases in which a particular supplement and dosing regimen has been recommended by a licensed medical doctor for a given child. Everyone should seek medical advice before taking melatonin supplements. Some conditions associated with difficulties relating to sleep in which melatonin may be prescribed to children include attention deficit hyperactivity disorder (ADHD), autism and delayed sleep phase syndrome.

If you are concerned that your child, or a child in your care, may be affected by one of these, or another, condition, you can get a free symptom assessment by downloading the Ada app.

It is not recommended that anyone, of any age, use melatonin supplements nightly for a period of more than four weeks. If the supplements have not provided relief from difficulties falling asleep during the timeframe recommended by a doctor, a new treatment approach must be explored.

Q: Who should not take melatonin supplements?
A: People should not take melatonin supplements if they:

  • Are under the age of 20, and have not sought medical advice
  • Are pregnant or breastfeeding
  • Are affected by an immune disorder, such as HIV
  • Are affected by seizures
  • Are affected by depression
  • Are taking medications which are known to interact with melatonin. (See Melatonin supplements: drug interactions.)

Q: Can I drink alcohol while using melatonin supplements?
A: Drinking alcohol while taking melatonin supplements is not recommended, as it is believed to reduce their effectiveness.[18]


  1. Light, melatonin and the sleep-wake cycle.” Journal of Psychiatric Neuroscience. 1994. Accessed: 19 December 2018.

  2. Melatonin: in depth.” National Center for Complementary and Integrative Health. 16 July 2018. Accessed: 19 December 2018.

  3. Melatonin.” Drugbank. 05 November 2018. Accessed: 19 December 2018.

  4. Melatonin.” Encyclopedia Britannica. 2018. Accessed: 19 December 2018.

  5. Neurotransmitters of the suprachiasmatic nuclei.” Journal of Circadian Rhythms. 16 February 2006.

  6. Melatonin dosing: herbs/suppl.” Medscape. 2018. Accessed: 21 March 2018.

  7. Dietary factors and fluctuating levels of melatonin.” NCBI. 20 July 2012. Accessed: 18 September 2017.

  8. Melatonin as adjuvant care with and without chemotherapy: A systematic review and meta-analysis.” Journal of Clinical Oncology. 2010. Accessed: 17 April 2018.

  9. The Therapeutic Potential of Melatonin: A Review of the Science.” Medscape. 2004. Accessed: 21 December 2018.

  10. Melatonin for Sleep: Does it Work?” John Hopkins Medicine. Accessed: 18 September 2017.

  11. Circadian rhythm disorders among adolescents: assessment and treatment options.” Medical Journal of Australia. 21 October 2013. Accessed: 19 December 2018.

  12. Melatonin.” Nottingham Children’s Hospital, NHS Trust. January 2014. Accessed: 19 December 2018.

  13. Is melatonin safe for children?” Medscape. 05 February 2003. Accessed: 21 December 2018.

  14. Melatonin for sleep disorders in visually impaired children.” Cochrane. 09 November 2011. Accessed: 19 December 2018.

  15. Dissolution of intact, divided and crushed circadin tablets: prolonged vs. immediate release of melatonin.” Pharmaceutics. 2016. Accessed: 19 December 2018.

  16. Effects of melatonin administration on daytime sleep after simulated night shift work.” Journal of Sleep Research. 12 June 2013. Accessed: 19 December 2018.

  17. Melatonin side-effects.” Drugs.com. 2018. Accessed: 19 December 2018.

  18. Melatonin: information for primary care.” North of Tyne Area Prescribing Committee: NHS. May 2013. Accessed: 19 December 2018.