More than 50% of adults have trouble falling or staying asleep at least a few times per week, according to a study by the National Sleep Foundation.

Yikes.

No wonder some of us are seeking help from nighttime sleep aids, like melatonin supplements.

"Getting quality sleep is obviously important for waking up feeling well-rested, but it's also critical for our overall health," says Dr. Rashad Ramkissoon, a primary-care physician at Houston Methodist. "A lack of quality sleep over time is linked to a wide range of health issues, from high blood pressure to obesity — so it's important to take steps to ensure you're getting a good night's rest."

When you're not, is taking melatonin really the answer?

What is melatonin?

"Melatonin is a hormone your body naturally produces to promote drowsiness, helping to coordinate the transition from being awake to asleep," explains Dr. Ramkissoon. "As a component of your sleep-wake cycle, its release is timed by the onset of darkness, so a few hours before bedtime."

As natural light disappears in the evening, melatonin levels start rising, preparing your body for sleep. These levels peak in the middle of the night and then gradually fall through the early morning hours until, finally, you're awake.

Melatonin supplements, on the other hand, are synthetically derived versions of this hormone that you can buy at the store, marketed as a way to fall asleep faster and stay asleep longer. The theory is that adding more melatonin on top of what your body is already releasing might help ensure good sleep.

But Dr. Ramkissoon says that combatting poor sleep might not be as simple as increasing your melatonin levels.

Does melatonin work?

Many studies have examined whether melatonin supplements benefit sleep and ... the results are mixed.

"From poor study design to its generally low potency, there is a lack of data supporting the use of supplemental melatonin as a clinically meaningful way to improve sleep," says Dr. Ramkissoon. "For instance, there's no evidence that it promotes sleep maintenance or can prevent insomnia."

Melatonin may have an effect, albeit a fairly minor one, on falling sleep, though.

A 2020 systematic review of 12 studies evaluating melatonin found small improvements in sleep onset — and perhaps even total sleep time, although this was only seen in a few studies.

"Taken together this data supports what we know about the role of melatonin, whether naturally made or synthetic," says Dr. Ramkissoon. "It doesn't induce sleep. It promotes sleepiness. This distinction is important because it helps explain why supplemental melatonin has minor, limited impacts on sleep."

Melatonin helps make you drowsy, but plenty of our everyday behaviors can fight against its effects, including:

• Screen time before bed
• Keeping an irregular sleep schedule
• Drinking caffeine or napping in the afternoon
• Eating a meal or drinking alcohol just before bedtime
  
  

(Related: QUIZ: Are These Afternoon & Evening Habits Ruining Your Sleep?)

In other words, a melatonin supplement might help you fall asleep — but it won't keep you asleep. And it's not powerful enough to fight against the habits that commonly lead to poor sleep, like staring at your phone for an hour before bed.

Is it bad to take melatonin every night?

Regardless of whether it truly helps with sleep or not, Dr. Ramkissoon doesn't recommend taking melatonin long-term.

"Namely, because if you think you need to take melatonin every night to get to sleep, we need to understand why that's the case," explains Dr. Ramkissoon.

Is poor sleep caused by a lifestyle habit that needs correcting — or some underlying issue that needs to be addressed?

"Melatonin isn't a long-term fix for sleep issues," Dr. Ramkissoon adds. "If you're consistently suffering from insomnia, we need to determine why and find an effective solution for it."

What's more is that the safety of using melatonin long-term hasn't been established in well-controlled studies.

And while the occasional, short-term use of melatonin — such as to combat jet leg or adjust to shift work — does appear to be safe for most people, this isn't the case for everyone.

Don't take melatonin if you're pregnant or breastfeeding. And know that these supplements can interact with other medications, such as some blood thinners, and that they may not be safe to take if you have certain health conditions.

"It's always important to consult your doctor before taking a new supplement," adds Dr. Ramkissoon.

How long does melatonin's effect last?

If you do decide to take a melatonin pill now and then, the timing of when you take it matters.

"Your body absorbs melatonin fairly rapidly, and its half-life — meaning the time it takes for your body to eliminate half of what you took — is about 20 to 50 minutes," says Dr. Ramkissoon.

Since its job is to help promote sleepiness, this means you'll want to take melatonin about 30 minutes to an hour before you plan to fall asleep.

"What you don't want to do is take melatonin at bedtime since this can shift when melatonin levels peak and, therefore, also when they fall — meaning you could be sleepier later into the morning," explains Dr. Ramkissoon. "Additionally, taking melatonin later than your planned usual bedtime can throw of your sleep-wake cycle."

How much melatonin is too much?

The various melatonin supplements available are typically formulated into doses ranging from 1 mg to 10 mg. Some are even higher.

So ... how much melatonin should you take?

Generally speaking, you don't need a dosage above 5 mg, but, in reality, the ideal dosage isn't well-established and likely varies from person to person.

"Some evidence suggests that doses below 1 mg are often as effective as higher doses, so it's best to start with the lowest dose possible and see what works for you," recommends Dr. Ramkissoon.

What are the side effects of melatonin?

"While many studies have examined melatonin, the side effects aren't firmly established," says Dr. Ramkissoon.

The most commonly reported melatonin side effects include:

• Vivid dreams
• Nightmares
• Dizziness
• Daytime sleepiness
• Headache
  
  

"Certain studies also report short-term feelings of depression and irritability, as well as stomach cramps," adds Dr. Ramkissoon.

Lastly, since supplements aren't regulated by the FDA like over-the-counter and prescription medications are, you'll need to do some research to be sure you're getting a quality product that has undergone testing and been certified by an independent third-party laboratory, such as NSF.

For instance, a 2017 study testing more than 30 different melatonin supplements found that the amount of melatonin in the product often didn't match what was listed on the label, and that some products contained ingredients other than melatonin. These are issues that can affect the side effects a person experiences, as well as the product's overall safety.