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How Long Does Melatonin Last?

Melatonin is a hormone that plays a vital role in regulating the sleep-wake cycle. It's also available as a supplement to aid sleep. Explore how long melatonin lasts in the body, how long it stays in the system, the time it takes to flush it out, and the time it takes to kick in.

How Long Does Melatonin Stay in Your System?

Melatonin doesn't last long in the body. Its half-life is 40 to 60 minutes, meaning half of the initial dosage is eliminated after that amount of time. In total, melatonin stays in the system for about four to five hours. Factors like age, dose, and formulation can affect how long it takes for the body to process melatonin.

Melatonin for Specific Conditions

  • Short-Term Sleep Problems in Adults: One 2mg slow-release tablet taken 1 to 2 hours before bedtime for up to 13 week.
  • Longer-Term Sleep Problems in Adults: Dose may gradually increase, depending on the condition.
  • Treatment of Jet Lag in Adults: One 3mg standard tablet for up to 5 days.

How Long to Take Melatonin?

For short-term sleep problems, Melatonin is usually taken for 1 to 4 weeks, although it can be prescribed for up to 13 weeks. For longer-term sleep problems, a specialist may prescribe treatment for more than 13 weeks. For jet lag, melatonin can be taken for a maximum of 5 days.

How Long Does Melatonin Take to Work/Kick In?

The body absorbs melatonin rapidly, with levels peaking within 1 hour. At this point, a person may begin to feel drowsy. However, everyone metabolizes drugs differently, and the time it takes for melatonin to act on the body also depends on its formulation.

Factors Affecting Melatonin Response

Several external factors may affect how the body responds to melatonin, including:

  • Age
  • Overall health status
  • Body composition
  • Using other medication
  • Tobacco use
  • Caffeine intake
  • Sleep hygiene (habits and environmental factors that promote higher sleep quality)

Immediate-release melatonin may help people fall asleep shortly after taking it, while the extended-release formulation may help people stay asleep throughout the night. Poor sleep habits, such as exposure to electronics or other sources of bright, artificial light, may tell the brain to stay awake longer.

How Fast Does Supplemental Melatonin Work?

Melatonin supplements are available in various doses and formulations. The typical dose ranges from 1 to 5 mg. Slow-release tablets gradually release melatonin into the body during the night, while fast-release formulations are absorbed more quickly.

Most people will feel the benefits of supplemental melatonin about two hours after taking it.

There are various formulations of melatonin available to cater to different sleep-related issues.

Types of Melatonin Formulations

  • Immediate-release melatonin tablets: Dissolve rapidly, instantly releasing melatonin into the bloodstream.
  • Extended-release melatonin: Dissolves slowly, gradually releasing melatonin over several hours.

One such formulation is Circadin, which contains synthesized Melatonin. It works to induce and promote sleep as per the circadian rhythm and is often prescribed for secondary insomnia in adults and off-label for jet lag .

Other forms of melatonin include:

  • Melatonin Patches: Release melatonin into the bloodstream more slowly.
  • Melatonin Melts: Fast-acting melts that dissolve under the tongue.
  • Melatonin Gummies: Widely available, but researchers have not yet discovered how quickly they take effect.

Depending on the type of supplement, the effects may kick in as quickly as 20 minutes.


Melatonin serves as a beneficial aid for those facing sleep-related challenges. Recognizing how quickly it takes effect and how to use it appropriately is key to obtaining the desired outcomes.

Melatonin's presence in the body is brief, with a half-life of upto 1 hour, signifying that this duration is required for the body to eliminate half of the substance.

Always adhere to the instructions that accompany your medication, and consult with a healthcare provider if you have any questions or uncertainties.

Authored & Reviewed By

Mohamed Imran Lakhi

MPharm - Lead Pharmacist
Imran Lakhi is the superintendent pharmacist and founder at Prescription Doctor. He has been at the core of our team.

Published on: 17/08/2023 Reviewed on: 01/11/2023
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