Melatonin is a hormone that controls your circadian rhythm. Your body makes it when you’re exposed to darkness. As your melatonin levels increase, you start to feel calm and sleepy.

In the United States, melatonin is available as an over-the-counter (OTC) sleep aid. You can find it at the drugstore or grocery store. The supplement will last in your body for about 5 hours.

Some people need additional melatonin to regulate their circadian rhythm. It’s used to help circadian rhythm disorders in:

  • travelers with jet lag
  • shift workers
  • people who are blind
  • people with dementia
  • people who take certain medications
  • children with neurodevelopmental disorders, like autism spectrum disorder

But melatonin isn’t just for sleeping better. It’s also used for migraine, attention deficit hyperactivity disorder (ADHD), and irritable bowel syndrome (IBS).

Let’s explore how melatonin works, along with how long it lasts and the best time to take it.

Melatonin is produced by the pineal gland, which is located in the middle of your brain.

The pineal gland is controlled by the suprachiasmatic nucleus (SCN). The SCN is a group of neurons, or nerve cells, in your hypothalamus. These neurons control your body clock by sending signals to each other.

During the day, the retina in the eye absorbs light and sends signals to the SCN. In turn, the SCN tells your pineal gland to stop making melatonin. This helps you stay awake.

The opposite happens at night. When you’re exposed to darkness, the SCN activates the pineal gland, which releases melatonin.

As your melatonin levels increase, your body temperature and blood pressure drop. The melatonin also loops back to the SCN and slows down neuronal firing, which prepares your body for sleep.

Melatonin is quickly absorbed by the body. After you take an oral supplement, melatonin reaches its peak level in about 1 hour. You may start to feel sleepy at this point.

But like all drugs, melatonin affects everyone differently. It might take more or less time for you to feel the effects.

Extended release melatonin vs. regular melatonin

Regular melatonin tablets are immediate release supplements. They dissolve as soon as you take them, which instantly releases melatonin into your bloodstream.

On the other hand, extended release melatonin dissolves slowly. It gradually releases melatonin over time, which may mimic the way your body naturally makes melatonin throughout the night. This is thought to be better for staying asleep at night.

Extended release melatonin is also known as:

  • slow release melatonin
  • continuous release melatonin
  • time release melatonin
  • prolonged release melatonin
  • controlled release melatonin

A doctor can help you decide if you should take regular or extended release melatonin.

Generally, the proper dose of melatonin is 1 to 5 mg.

It’s recommended to start with the lowest dose possible. You can slowly increase your intake to determine the best dosage that helps you fall asleep without causing adverse effects.

After all, taking too much melatonin can be counterproductive. A melatonin overdose can disrupt your circadian rhythm and cause daytime sleepiness.

It’s important to note that melatonin isn’t strictly regulated by the Food and Drug Administration (FDA). That’s because melatonin isn’t considered a drug. Therefore, it can be sold as a dietary supplement like vitamins and minerals, which aren’t closely monitored by the FDA.

Since the rules are different for dietary supplements, a manufacturer can list an inaccurate dose of melatonin on the package. There’s also very little quality control.

Even then, it’s a good idea to follow the instructions on the package. If you’re not sure how much you should take, talk to a doctor.

It’s recommended take melatonin 30 to 60 minutes before bedtime. That’s because melatonin typically starts working after 30 minutes, when levels in your blood rise.

However, the best time to take melatonin is different for each person. Everyone absorbs medication at different rates. To start, take melatonin 30 minutes before bed. You can adjust the timing depending on how long it takes for you to fall asleep.

What’s most important is that you avoid taking melatonin at or after your ideal bedtime. This can shift your body clock in the wrong direction, resulting in daytime sleepiness.

Melatonin doesn’t last in the body for long. It has a half-life of 40 to 60 minutes. The half-life is the time it takes for the body to eliminate half a drug.

Typically, it takes four to five half-lives for a drug to be fully eliminated. This means melatonin will stay in the body for about 5 hours.

If you stay awake during this time, you’re more likely to feel aftereffects like drowsiness. That’s why it’s recommended to avoid driving or using heavy machinery within 5 hours of taking it.

But remember, everyone metabolizes drugs differently. The total time it takes to clear will vary for each person. It depends on several factors, including:

  • age
  • caffeine intake
  • whether you smoke tobacco
  • overall health status
  • body composition
  • how often you use melatonin
  • taking extended release vs. regular melatonin
  • other medications

You’re less likely to feel a “hangover” if you take melatonin at the right time. If you take it too late, you may feel drowsy or groggy the next day.

In general, melatonin is considered safe. It primarily causes sleepiness, but this is its intended purpose and not a side effect.

The most common side effects of melatonin are mild. These may include:

Less common possible side effects include:

You’re more likely to experience these side effects if you take to too much melatonin.

Despite its high safety profile, melatonin isn’t for everyone. You should avoid melatonin if you:

  • are pregnant or breastfeeding
  • have an autoimmune disease
  • have a seizure disorder
  • have kidney or heart disease
  • have depression
  • are taking contraceptives or immunosuppressants
  • are taking drugs for hypertension or diabetes

As with any supplement, talk to a doctor before taking it. They might want you to take certain safety precautions while using melatonin.

In general, you should take melatonin 30 to 60 minutes before bedtime. It typically takes 30 minutes to start working. Melatonin can stay in your body for about 5 hours, though it depends on factors like your age and overall health status.

It’s possible to overdose on melatonin, so start with the lowest dosage possible. Using too much melatonin can disrupt your circadian rhythm.