How Long Does It Take for Melatonin to Work?

If you haven’t been sleeping well, you may be exploring options to help you get more rest. Perhaps you've looked into adjusting your nightly routine, decreasing stress, or changing your sleep environment. If you've tried making lifestyle adjustments but are still having sleep concerns, you may be considering adding the naturally occurring hormone melatonin to your nightly routine as a supplement. This article highlights the available forms of melatonin, how long it takes for each form to work in the body, and the benefits and risks of melatonin use.

How does melatonin work?

Melatonin is a naturally occurring substance made by your brain that regulates your body’s sleep-wake cycle, known as a circadian rhythm. When levels of melatonin increase in the body, it signals your brain that it is time to sleep.

Melatonin levels rise and fall in response to changes in darkness and light during the day. To promote sleep, the pineal gland in your brain converts the chemical substance serotonin to melatonin. As a result, your body temperature and blood pressure decrease, leading to drowsiness. This process typically takes place in the evening before dark. The greatest amount of melatonin is present during darkness, and as you are exposed to light, your levels of melatonin decrease.

The process of rising and falling melatonin levels within a 24-hour period should occur naturally, but you may have a disrupted circadian rhythm. There are a number of reasons that can interrupt your natural sleep-wake cycle, including shift work or travel across time zones. If your sleep patterns have been disrupted, you may want to talk with your physician to see if a melatonin supplement can help you with restful sleep. In the United States, melatonin is available as a supplement and is not Food and Drug Administration (FDA) approved.

How long does it take your body to process melatonin?

Oral melatonin absorption and metabolism vary from person to person. The amount of time melatonin stays in your system depends on the form of melatonin you use and the speed of your body's metabolism. More rapid forms of melatonin are absorbed faster, but they don’t last as long in your system. Slower, extended-release forms of melatonin will stay in your system much longer, but they are absorbed more slowly.

Oral melatonin reaches peak blood concentration between 20 min and 2 hours and maintains these levels for 1.5 hours. Melatonin has a half-life of about 40 minutes. That means that it takes 40 minutes for the levels of melatonin in your body to decrease by half. The other half of melatonin goes through your body over several hours. Most medications are eliminated in the body in 5 half-lives. This means that immediate-release oral melatonin stays in your body for about 3.5 hours. A prolonged release form of melatonin would stay in your body longer.

Data suggests oral melatonin should be taken approximately 30–60 min before attempting sleep. Optimal dosing has not been established and ranges from 0.5–5 mg by mouth taken 30–60 min before usual bedtime. Some studies suggest that the timing of when you take melatonin may be more important than the amount of melatonin you take.

Forms of melatonin

Melatonin is available in various forms. In the United States, you can purchase a melatonin supplement without a prescription. Even though you can get melatonin over-the-counter, you may still want to talk with your doctor about which form of melatonin may be the best choice for your situation.

Each form of melatonin may have a different rate of absorption, time to peak concentration, and amount of time that it lasts within the body. Let’s take a closer look at the various forms of melatonin and the key differences between each dosage form:

Type of melatoninTime to absorptionPeak plasma levelsHow long does it last in the bodyKey recommendations
Fast release oral (FR)About 20 min*About 36 min*About 3.5 hrsMay be more helpful for people who need help falling asleep; may wake up mid-sleep cycle because of the short half-life
Controlled release (CR or ER, extended-release)Absorbed slower than FRStays at peak plasma levels longer than FRIs eliminated from the body more slowly than FRMay be more helpful for people that need more help staying asleep
PatchAbsorbed slower than CR/ERStays at peak plasma levels longer than CR/ERIs eliminated from the body more slowly than CR/ER May be more suitable for shift workers and jet-lagged people because of the delayed release nature of the patch and longer maintenance at peak plasma levels
GummiesMay be absorbed faster or at the same rate as FRPeak plasma levels similar to FRElimination rate may be similar or faster than FRShould be used with caution in and around children; may be confused for candy and lead to accidental overdose

*Please note that the indicated numbers are based on specific studies. The actual time to absorption and peak plasma levels will depend on several factors, including individual metabolism, the form of melatonin, and others.

Factors that affect melatonin effects

Melatonin will affect each person differently. There are many factors that may affect the absorption and blood levels of melatonin supplements. Some factors include:

  • Gender. Women tend to have higher levels of melatonin circulating in their blood after using supplements than men.
  • Patch size. A smaller dose delivered in a smaller patch releases melatonin at a rate that more closely mimics the natural release of melatonin than a higher-dose patch that is larger in size.
  • Caffeine use. The use of caffeine and other stimulants may have an impact on melatonin’s bioavailability.
  • Exposure to light. Natural levels of melatonin are affected by light and darkness. Attempting to sleep in an environment with bright lights will decrease your body’s melatonin levels. Use an eye mask or room darkening curtains, and avoid using electronic devices with bright lights at bedtime.
  • Age. Elderly people may metabolize drugs and supplements at a slower rate, which means more of the drug will stay in the body longer.
  • Dosage forms used. The type of melatonin you use will affect how fast or slow the supplement is absorbed, processed, and eliminated in your body.

Risks and side effects of melatonin use

Melatonin is considered safe for short-term use. If you use less than 10 mg of melatonin per day as a healthy adult, you will likely avoid side effects or overdose. Although the likelihood that you will experience side effects is minimal, it is possible. Potential adverse effects of melatonin overdose are light headache, nausea, and drowsiness.

Taking melatonin along with other substances that can cause drowsiness, such as alcohol, medications for depression, or controlled substances, can be dangerous and lead to severe sedation. If you take any medications that cause drowsiness, please talk with your physician about whether or not it is safe for you to start taking melatonin.

Who shouldn’t take melatonin?

Melatonin use is not recommended in elderly people with dementia. Physicians also recommend that people with seizure disorders and those taking blood thinner medications only use melatonin under medical supervision. There are a limited number of studies that have evaluated the safety of melatonin use in children/teens, and safety has not been established in pregnant or breastfeeding women. If you are pregnant or have children and are interested in using melatonin for yourself or your child, please talk with your doctor first.

Parents should also store melatonin supplements out of the reach of children.

Alternatives to melatonin

If you're having trouble sleeping, there are some natural changes you may want to make to your daily routine. These are changes you can easily try first before seeking medical guidance about supplements or prescriptions. Here are a few lifestyle changes to try:

  • Develop a bedtime routine. Your body’s natural sleep-wake cycle can be disrupted by inconsistent sleep patterns and environments. Try to go to bed at the same time each night and wake up at the same time, even when on vacation. Develop a relaxing nightly routine that consists of calming sounds or warm baths.
  • Sleep in a dark environment. Darkness should trigger your brain to naturally release some melatonin. Intentionally creating a dark environment for sleep will help with this. Use a sleep mask or room-darkening window treatments. Avoid using your cell phone, watching TV, or using other technology with bright lights at bedtime.

After you've made changes to your daily routine and sleep environment, if you're still having trouble, you may want to consider taking a supplement or prescription sleep medication. If you're unable to take melatonin but don’t want to use a prescription medication for sleep, here are some other options that you may want to discuss with your physician:

  • Use aromatherapy essential oils. Inhaling certain essential oils, like lavender, promotes relaxation, reduces anxiety, and may improve sleep quality.
  • Use chamomile. There are many forms of chamomile: teas, capsules, and tinctures. While the evidence is sparse, it may be beneficial in improving sleep quality.
  • Consider taking a magnesium supplement, especially if you have magnesium deficiency. According to observational studies, magnesium levels are linked to sleep quality. However, clinical trials show inconclusive findings regarding magnesium supplementation and sleep. Larger studies are needed for longer periods of time to further confirm magnesium’s effect on sleep. Please talk with your physician before starting a magnesium supplement.

Overall, short-term melatonin use should pose no side effects in healthy adults. However, it is always best to consult your healthcare provider before starting any supplement, especially if you have known health conditions or are taking medications. Before trying melatonin, consider alternatives and practice good sleep hygiene — this may help improve your sleep quality.

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