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Melatonin: How long does it last?

Melatonin is a naturally occurring sleep-promoting hormone. It is also accessible as an over-the-counter sleep aid (OTC). Depending on dose and various other variables, OTC melatonin remains in the body for between 2.5 and 10 hours.

People who are using or considering sleeping with melatonin may wonder how long it stays in the body.

In this article, we explore what melatonin is, how long it lasts, and how much to take. Potential alternatives to melatonin and its benefits and side effects are also included.

What is melatonin?

A sleeping young man

Melatonin is a hormone that influences the circadian rhythms of the body. Melatonin is produced by the pineal gland. The retinas in the eyes absorb light during the daytime hours, which tells the pineal gland to quit releasing melatonin. The decrease in light signals melatonin development as the sun sets.

When a person does not participate in a particular mental or physical activity, melatonin works on regions of the brain that are active. A Default Mode Network (DMN) is the collective term for these areas. Through its effects on the DMN, melatonin encourages sleep.

While melatonin is a hormone that happens naturally, it is also available for people who have trouble falling asleep or staying asleep through the night as an OTC sleep aid.

OTC melatonin can help control disorders of the circadian rhythm in:

  • night shift workers
  • people with jet lag
  • visually impaired people
  • blind people
  • people with dementia

In addition to promoting sleep, melatonin may help relieve anxiety before and after surgery. It may also help treat the following conditions:

  • cancer
  • metabolic disorders
  • cardiovascular disease
  • gastrointestinal (GI) disorders
  • neurodegenerative disorders
  • mental health disorders
  • pain syndromes
  • reproductive issues

How long does it last?

Melatonin is considered by the medical community as a dietary supplement close to vitamins and minerals that are not regulated by the Food and Drug Administration (FDA).

The average dosage is 0.1–10 milligrams ( mg) in adults.

Depending on either the formulation, melatonin has a half-life of around 1–2 hours. A half-life explains how long it takes for the body to metabolize half of a drug dose.

The body requires approximately 4-5 half-lives to eliminate a drug. This implies that, depending on the dosage and formulation, OTC melatonin remains in the body for 4-10 hours.

How long does it take to kick in?

The body easily consumes melatonin. The levels of melatonin peak within 1 hour. An individual may start to feel drowsy at this point.

Everybody metabolizes medicine differently. Some people can notice, sooner or later than others, the effects of melatonin. The time it takes to work on the body with melatonin also depends on its formulation.

Immediate-release tablets of melatonin dissolve easily, releasing melatonin into the bloodstream instantly. Extended-release melatonin slowly dissolves and, over several hours, activates melatonin steadily.

Depending on their individual sleep problems and how their body handles melatonin, one formulation can work better for some than for others. Shortly after taking it, immediate-release melatonin can help people fall asleep. On the other hand, the extended-release formulation can help individuals remain asleep during the night.

How the body reacts to melatonin can be affected by several external factors. They include:

  • age
  • overall health status
  • body composition
  • using other medication
  • tobacco use
  • caffeine intake
  • sleep hygiene

Sleep hygiene refers to habits and environmental variables that encourage a higher quality of sleep. Bad sleep habits can tell the brain to stay awake longer, such as exposure to electronics or other sources of bright, artificial light.

When to take melatonin?

Within 60 minutes, melatonin levels peak, so individuals should take melatonin 30-60 minutes before they plan to fall asleep.

That said, it is important to remember that not everybody is affected in the same way by melatonin. People will want to start taking a low dose of melatonin 30 minutes before sleeping. Depending on their particular sleep routine, they may adjust the timing and dosage.

In general , it is important that individuals do not take melatonin after their ideal bedtime. It can alter their sleep-wake cycle by doing so. An individual can fall asleep later than expected or suffer fatigue during the day.


Melatonin can help alleviate sleep problems that are mild or infrequent. Melatonin does, however, carry the possibility of mild side effects, such as:

Melatonin consumption also may lead to rebound insomnia, reliance, and liver problems.

Melatonin is a naturally occurring hormone, but the consistency or dosage of OTC melatonin is not controlled by the FDA. This implies that there might be incorrect dose information for certain OTC melatonin products.

Natural sleep aids include alternatives to melatonin, such as:

  • lavender
  • magnesium
  • lemon balm
  • passionflower

However, natural sleep aids are unregulated, similar to melatonin and other supplements. People can only buy from high-quality, reputable producers and distributors.

The following sleep hygiene habits may be tried by individuals who do not want to use OTC melatonin or other sleep aids:

  • maintaining a consistent sleep schedule by falling asleep and waking up around the same time each day, even on weekends
  • avoiding taking long naps in the evening
  • avoiding using electronics, such as televisions, computers, and cell phones, in the bedroom
  • developing a relaxing and consistent bedtime routine
  • doing relaxing activities, such as reading a book, meditating, or taking a bath, in the evening
  • avoiding eating large meals before bedtime
  • avoiding caffeine in late afternoon or evening
  • exercising during the day
  • keeping the bedroom at a comfortable temperature
  • falling asleep in a dark, quiet room


On average, within 30–60 minutes, melatonin takes effect. Depending on the dosage and formulation, OTC melatonin will remain in the body for 4–10 hours.

At or after their planned bedtime, people should stop taking melatonin. Doing so will adjust their sleep-wake cycle and result in sleepiness throughout the day.

Practicing good sleep hygiene will help people fall asleep more easily and stay asleep all night long.

If a person continues to experience insomnia or other issues with sleep, they may want to contact a doctor to explore other options for treatment.