The right amount of melatonin is crucial — and thanks to the way it's often sold, chances are that you're taking too much. "The proper dosage, according to a seminal 2001 study from the Massachusetts Institute of Technology, is 0.3 milligrams," Krithika Varagur wrote for the Huffington Post. However, many pills are sold as 3 grams or more — which represents a massive excess.

"Ninety percent of the melatonin that's sold currently is sold in an overdosage format," sleep expert Dr. Michael Breus tells Bustle. "If you look around, almost nobody sells it at [0.3 milligrams]; they sell it at three, five, even 10 milligrams." And that's a problem, because you can indeed get melatonin "hangovers," with too much of the substance in your body at the one time. More doesn't mean more sleep; it means you'll wake up feeling groggy and confused the next day.

Melatonin takes a small amount of time to work, and isn't instantaneous. Want it to knock you out right away? You're going to have to wait. "Most people don't realize that if you are ingesting melatonin in a pill format, it takes almost 90 minutes for plasma concentration levels [to become effective]," Breus tells Bustle. "You should be taking it like an hour and a half before bed. But most people don't. They take it like a sleeping pill. They take it right at bed." Cue tossing and turning for over an hour while you wait for it to help you.

Melatonin doesn't knock your lights out and leave you in a state of slumber till morning. It's not like a typical sleep aid, which slows down brain activity to induce slumber pretty rapidly; it's actually a hormone that controls sensitivity to light. When the sun goes down, Penn Medicine explains, "the pea-sized gland just above the center of your brain, called the pineal gland, starts to release melatonin into your bloodstream. As your levels of melatonin increase, you start to get drowsy."

Melatonin acts in response to lowering levels of light in the environment; it's what kicks in and makes you sleepy when you turn off your bedroom lights in the evenings. Your body naturally produces it on its own, and any extra is just an additional nudge in the direction of sleep, not a complete shutdown.

Many travelers have heard of the wonders of melatonin for helping jet lag, because it can help out with sensitivity to the new dawn and dusk in a fresh time zone. And it does work for that. "A 2002 Cochrane review — the gold standard in healthcare evidence — found melatonin can be effective against jet lag," Nic Fleming reported in The Guardian in 2017. "The analysis of 10 previous studies found that people crossing five or more time zones who take melatonin close to bedtime at their destination had less severe symptoms than those taking placebos."

However, melatonin shouldn't be your only approach for beating jet lag. Oxford professor Russell Foster told The Guardian, “It’s hard to know when to take it, and unless you know precisely where your internal clock is, there’s a danger of shifting it in the wrong direction.” Instead, trigger your own natural production of melatonin by getting sunlight during the daytime and darkening your environment around your new bedtime, to help the pineal gland kick in.

If you take melatonin, it's pretty common not to have asked your doctor about it first. "According to the study in Sleep, less than half of those who take melatonin supplements consult a physician," Myra Partridge wrote for EveryDay Health. "This may be an unwise choice because of the risk of interactions between these supplements and prescription medications or even other over-the-counter dietary supplements."

Melatonin may be natural, but it's not regulated like a medication under the FDA and so can be sold in differing quantities and strengths, which means you might need guidance on what you're ingesting. It can also produce daytime drowsiness if you consume it at the wrong times or in the wrong doses, so it's always good to have a doctor's advice on how to use it — and if you should take other steps to improve your sleep instead.

Melatonin can help, but it's not guaranteed to make your disrupted sleep automatically better. According to the Huffington Post, a 2013 study found that melatonin supplements helped people fall asleep “only 7 minutes faster and sleep 8 minutes longer on average." That's only a small boost overall, and doesn't address underlying issues that might be causing your sleep to be rocky.

Tried melatonin and found that it doesn't meet your expectations? It's possible that there's more complexity in your sleep issues than melatonin can change.

"In order to get a good night’s sleep, you still need to follow healthy sleep habits, such as avoiding your phone and other tech devices in the hour before bed and winding down in the evening with a relaxing activity or bedtime ritual," the National Sleep Foundation says. So no, melatonin doesn't mean you can stay on your phone 'til bedtime and still expect to feel refreshed and amazing in the morning.

Melatonin can be a great help, but it has its limits and its drawbacks. It's a good idea to take it responsibly, preferably with a doctor's advice, to get the most out of it.