Do you sometimes pull the adult version of an all-nighter? You’re not necessary staying up all night, but you’re staying up (or out) later than you should. Perhaps you’re working late trying to wrap up a big presentation you’ve got to give tomorrow. Or maybe you’re taking out-of-town clients out for dinner and drinks, laying the groundwork for a big contract. Either way, that up-too-late schedule can totally derail a good night’s sleep.

After a late night—especially if you’ve been drinking—you might be exhausted. You toss and turn, but either just can’t fall asleep or struggle to stay asleep. While alcohol does have a sedative effect initially (thus helping you to fall asleep), it sometimes interferes with your ability to stay sleep. 

Besides alcohol, many factors contribute to sleep disruption, from stress, medication, and shift work to caffeine, sleep environment, and jet lag.

In fact, according to the National Institutes of Health, up to 19% of American adults say they’re not getting enough shut-eye every day. And a chronic lack of sleep can wreak havoc on your well-being, both physically and mentally.  

Do you fall into this camp of either being chronically sleep deprived or at least occasionally tired? If so, you might turn to melatonin to help you sleep through the night.

But what, exactly, is melatonin? And how long does melatonin last? Let’s find out.

What is melatonin?

Unlike traditional “sleeping pills” which can be habit-forming and lead to serious long-term side effects, melatonin can be found in the dietary supplement aisle without a prescription. As an over-the-counter supplement, melatonin has surged in popularity recently as a 100% drug-free sleep aid, helping many people fall (and stay) asleep.

Your brain naturally produces melatonin (which is actually a hormone) in response to darkness, so scientists have found a way to harness its sleep-inducing properties. Melatonin plays a role in your body’s internal clock known as the body’s circadian rhythm, which controls your 24-hour sleep/wake cycle. As darkness sets in, your brain’s pineal gland starts producing melatonin to cue your body that it’s time to prepare for sleep. And, as your melatonin levels rise, you start to relax, your blood pressure decreases, your body temperature drops, and you start to feel sleepy. Aw, sweet slumber, come hither!

However, if you’re exposed to light at night (such as if you’re at a brightly lit bar, club, or restaurant), this can block melatonin production. The same holds true for the ubiquitous blue light emitted from electronic devices (think TV, cell phone, or computer.) The end result? All of this light messes with your sleep because melatonin production decreases or stops altogether.

Some people also turn to melatonin to treat jet lag, which can negatively impact your sleep. If you’re flying across time zones for business meetings or to entertain clients, you can probably relate to that sluggish feeling you experience trying to adjust to an earlier (or later) time than your “home base.” To the rescue? Melatonin!

How much melatonin should you take?

While melatonin supplements are generally sold in dosages ranging between 1 to 10 mg, healthcare professionals typically recommend taking 0.5-5 mg. And, of note, they recommend starting with the lowest possible dose to see what helps you fall asleep and stay asleep without any side effects. If you can get by on a 3 mg dosage, take that. But if a 10 mg dosage causes adverse effects, such as making you groggy during the day or causing headaches, then cut back to a lower dose.

When should you take a melatonin supplement? Because people metabolize supplements (and medicine) at different rates, when to take melatonin can vary. Experts generally suggest taking a melatonin supplement about 30 minutes to two hours before you plan to head to bed. Why? Because it usually takes that long for melatonin to start kicking in, coinciding with the body’s naturally increasing melatonin levels. But if you find it takes you longer to fall asleep, you might need to adjust the time of when you take melatonin, either increasing it or decreasing it as needed. Just like adjusting the dosage, you need to understand what timing works best for you to improve sleep quality without causing any ill effects.

One key point to remember—don’t take melatonin right at your normal bedtime. Taking it later is even worse. Doing so can cause daytime sleepiness, which is definitely not what you want to feel when you’re trying to perform at work the next day.

How long does melatonin last?

It depends. How long melatonin lasts really depends on the dosage, the type of supplement (quick-release or long-lasting), and how your body processes the supplement, since it affects everyone differently.

Immediate release melatonin supplements are just like they sound—they dissolve instantly and immediately release melatonin into your bloodstream. This helps you fall asleep faster.

Extended release melatonin supplements dissolve slowly—they gradually release melatonin over several hours. This more naturally mimics the time frame that your brain produces this sleep-inducing hormone throughout the night. This helps you stay asleep during the night.

According to the Sleep Foundation, “melatonin is fast-acting, with a half-life of 20 to 40 minutes.” The half-life basically means how long it takes the body to process and eliminate half the dosage, whether it’s medicine or a supplement.  Researchers found that, after taking a regular dose of 1 to 5 mg of melatonin, participants’ melatonin levels reached their peak within an hour. This is when you’ll likely start to feel tired. The study also found that melatonin levels returned back to normal after four to eight hours.