Studies estimate that 50–70 million adults in the US have a sleep disorder, so it’s no surprise that sleep aids like melatonin are on the rise.¹
In the United States, melatonin is available as a dietary supplement. It’s one of the most commonly used supplements among adults and children. An increasing number of Americans are using over-the-counter melatonin to aid their sleep.²
Researchers examined data collected by the National Health and Nutrition Examination Survey (NHANES). It surveyed 55,000 adults between 1999 and 2018. Melatonin use increased to 2.1% in 2017–2018 from 0.4% in 1999–2000. The study discovered a similar trend between men and women and across age groups. In 2018, 154 melatonin users took dangerously high amounts of more than 5mg a day compared to 44 in 1999–2000.³
A small dose works for most people, with 0.2–0.5mg often sufficient.
While scientists believe supplementing melatonin is relatively safe, it may not be beneficial for everyone. As sleep is incredibly complex, using melatonin as a quick fix may merely cover up deeper issues that need resolving.
The pineal gland in your brain creates melatonin before releasing it into your bloodstream. Scientists call it the hormone of darkness because darkness prompts your pineal gland to start producing melatonin, while light stops that production.⁴
As a result, melatonin regulates your circadian rhythm and synchronizes your sleep-wake cycle with night and day. It promotes quality and regular rest by transitioning you to sleep.⁵
The melatonin your body creates is “endogenous melatonin.” Endogenous simply means something created inside your body. Melatonin can also be lab-created, which is “exogenous” — created outside the body. This type of melatonin is synthetic. As a dietary supplement, it’s most often a chewable, pill, capsule, or liquid.
Let’s look at the evidence for melatonin for sleep. Researchers have carried out many studies on the effect of melatonin supplements, and the results are mixed.
With 33–50% of the population dealing with insomnia, we would expect to see detailed studies on melatonin’s efficacy. However, there’s debate about whether melatonin is helpful in adults with insomnia, and existing research isn’t conclusive.⁶
One 2017 study found evidence in favor of melatonin and suggested it as a first-line treatment for sleep-onset insomnia. Still, the same study revealed that melatonin only increased total sleep time by 8.3 minutes.⁷
The American Academy of Sleep Medicine (AASM) stated insufficient scientific support for melatonin easing insomnia.⁸
While the jury is still out on melatonin for insomnia, it may be helpful in the case of delayed sleep-wake phase disorder (DSWPD). This is a circadian rhythm disorder where a person can only fall asleep later than is generally acceptable, sleeping in late to compensate. DSWPD causes issues with 9–5 jobs and other responsibilities.
Studies have revealed that low doses of melatonin may help. If the affected person takes melatonin before their desired bedtime, they can adjust their sleep cycle.⁹
Scientists have regularly studied the effects of working night shifts on our bodies, and the adverse effects are extensive. A 2020 systematic review and meta-analysis examined the link between night shift work and melatonin production. The researchers discovered that fixed night shifts are associated with natural melatonin production suppression.¹⁰
Several small studies have revealed mixed results on the efficacy of melatonin supplementation for night shift workers. A 2001 study suggested that shift workers may even develop a tolerance to melatonin and struggle regardless as shift work goes against their circadian rhythms.¹¹
Small studies have indicated that melatonin supplements effectively reset the sleep-wake cycle and improve sleep in people with jet lag. However, in the UK, the National Health Service (NHS) does not recommend melatonin for jet lag as there isn’t enough evidence that it works. An expert review stated there is “Scant evidence that it effectively relieves symptoms of (a) short term, highly variable condition.”¹² ¹³
Several research studies have demonstrated that melatonin may help children with sleeping difficulties fall asleep faster and increase their total sleep time.¹⁴ ¹⁵
The American Academy of Pediatrics (AAP) says melatonin may be a valuable short-term tool for adjusting children to a better sleep schedule and establishing healthy sleep habits.
Small studies unearthed evidence of melatonin being useful in children with certain conditions. These include epilepsy and neurodevelopmental disorders such as autism spectrum disorder (ASD).¹⁶ ¹⁷
The AAP strongly advises consulting a pediatrician before giving your child melatonin. There are many uncertainties regarding melatonin supplements in children.
Melatonin may seem like a quick fix for your sleep troubles, but there is limited evidence on the effects of long-term supplementation. The National Center for Complementary and Integrative Health (NCCIH) says that short-term melatonin use appears to be safe for most adults and children.
While some countries consider melatonin a drug, the US classifies it as a dietary supplement. This means the US Food and Drug Administration (FDA) doesn’t regulate it as strictly as medicine. The problem with that? Melatonin supplements could have purity, quality, or content issues. Studies revealed that the actual melatonin content in some supplements could be as high as 478% more than what’s on the label.¹⁸ ¹⁹
More isn’t better. If you take higher doses of melatonin, it increases your chance of side effects. Another concerning discovery was that 26% of melatonin products contained serotonin. It can be harmful even in small doses, and these effects could be deadly when combined with SSRIs. Serotonin syndrome is very serious and life-threatening.²⁰
The American Academy of Sleep Medicine (AASM) recommends looking for the USP Verified Mark on melatonin supplements. This mark indicates that the product meets the conditions of the US Pharmacopeial Convention (USP). USP is a scientific nonprofit setting quality standards for medicines and supplements to ensure everyone can access safe remedies.²¹ ²² ²³
All supplements and medicines cause side effects, and melatonin is no different.
The most common melatonin side effects are:
Less common side effects include:
Temporary feelings of depression
Disorientation or confusion
Low blood pressure (hypotension)
As melatonin can cause daytime drowsiness, you shouldn’t drive or use machinery within five hours of taking it. This effect is especially pronounced in older adults.
Guidelines from the American Academy of Sleep Medicine (AASM) have warned against using melatonin and sleep-promoting medicines in people with dementia. Older adults often struggle with insomnia due to a natural decline in melatonin production. However, supplementing melatonin can increase the risk of falls and other adverse events. Caregivers noted that patient mood was worse in people with dementia. ²⁴
Melatonin can be unsafe if you have:²⁵
If you’re pregnant and looking to supplement melatonin, there hasn’t been much research to prove that it’s safe for your unborn baby. Despite animal studies suggesting the opposite, melatonin use during pregnancy and breastfeeding is probably safe for humans, according to a study review published in 2021.²⁶
You may prefer to speak to your primary care doctor about other ways to improve your sleep rather than rely on a study’s “probably safe” verdict.
It is best to avoid taking melatonin if you’re pregnant or breastfeeding, as there isn’t enough research to know whether it’s safe for you and your baby. If you are planning on taking medication or supplements when pregnant or breastfeeding, consult your doctor to make sure it is safe.
Melatonin passes to your baby in small amounts while you’re breastfeeding. This can make your baby more sleepy. Extreme tiredness in your baby can seriously impact their health. If they cannot fully wake up, they may develop jaundice or fail to thrive.²⁷
While researchers believe melatonin is safe for most people, it can cause potentially dangerous drug interactions.
A 2019 CDC study revealed that 48.6% of the US population and 88.5% of those over 65 had taken at least one prescription drug in the 30 days prior. The Health Policy Institute at Georgetown University stated that more than 131 million people — 66% of US adults — use prescription drugs.²⁸ ²⁹
There are 276 drug interactions with melatonin, and only a few are minor. A few common drug interactions include:³⁰
Examples: Warfarin, aspirin, clopidogrel, and fish oil (omega-3 fatty acids)
What they do: They reduce blood clotting by thinning your blood.
Interaction with melatonin: It might increase the risk of bleeding.
Examples: Gabapentin, pregabalin, clonazepam
What they do: They treat epileptic seizures and some mental health conditions.
Interaction with melatonin: It might inhibit anticonvulsants’ effects and increase the frequency of seizures. This is particularly a concern in children with neurological difficulties.
Examples: Lisinopril, metoprolol, losartan
What they do: They control your blood pressure and prevent cardiovascular events.
Interaction with melatonin: It might worsen blood pressure.
Examples: Diazepam, lorazepam, alprazolam
What they do: They treat insomnia, panic attacks, anxiety, and seizures.
Interaction with melatonin: It may cause an additive sedative effect.
Examples: Ethinyl estradiol-levonorgestrel, progesterone
What they do: They prevent pregnancy and regulate the menstrual cycle.
Interaction with melatonin: It can cause an unwanted sedative effect and increased melatonin side effects.
What they do: They regulate your blood glucose to reduce the risk of hyperglycemia.
Interaction with melatonin: It might affect blood sugar levels.
Example brands: Luvox, Faverin, Fluvoxin
What it does: It treats obsessive-compulsive disorder (OCD).
Interaction with melatonin: It increases melatonin and causes excessive drowsiness.
Examples: Adalimumab, prednisone, tacrolimus
What they do: They reduce the strength of your immune system, reducing the chance of your body rejecting a transplanted organ.
Interaction with melatonin: It stimulates immune function and interferes with immunosuppressive therapy.
Examples: Citalopram, sertraline, fluoxetine
What they do: They treat depression, anxiety, and other mental health conditions.
Interaction with melatonin: It may increase dizziness, drowsiness, and confusion.
Typically, melatonin is safe for short-term use, but there’s limited research on its long-term effects. While melatonin may be a helpful supplement for some, there’s no guarantee it will work for you. You may also encounter undesirable side effects, even though they’re usually mild. There’s also the concern that it’s unregulated, so you could easily take too much.
It also may not be safe for you if you’re taking any medication, are pregnant, breastfeeding, or have pre-existing conditions. It’s best to speak to your doctor before taking melatonin so they can advise you if it’s appropriate in your case and suggest a dosage.
If you’re already taking melatonin and it’s not working, or you’re dealing with side effects, stop taking it and ask your doctor for their advice. They will be able to recommend better options for a good night’s sleep.
But what are the better options?
Trying to sleep in a cluttered room with too much light can be tricky at the best of times, let alone if you have a sleep-wake disorder.
Making sure your room is dark, quiet, and cool can improve your sleep. Removing any clocks in the room can be helpful, too, as it’s easy to get stressed about the time when you can’t sleep. You should put your phone away, as scrolling through social media isn’t going to help you snooze.
Sleep hygiene includes lifestyle changes that promote good sleep:
Go to bed and get up at the same time every day.
Establish a bedtime routine. This may involve chamomile tea and a warm bath.
Put away electronics an hour before bedtime.
Avoid heavy, fatty meals before bed.
Skip the caffeine, alcohol, and nicotine. They make it harder for you to sleep.
Adding a 30-minute exercise session to your day can reduce how long it takes you to fall asleep. Regular exercise can also help you sleep better and longer.
Stress and anxiety can cause sleeping problems or make a pre-existing issue worse. Meditation and exercise are great ways to boost your mental health, but it’s worth making an appointment with your doctor if you’re struggling.
You’ve probably heard of cognitive behavior therapy (CBT). Cognitive behavior therapy for insomnia (CBTI) specifically focuses on insomnia. It’s a great tool to have in your arsenal.
The American College of Physicians (ACP) and the American Academy of Sleep Medicine recommend CBTI as the first line of treatment for chronic insomnia. It can also help with other sleep disorders.
Your therapy sessions may include educational, cognitive, and behavioral components. These include altering your thoughts about sleep, giving you tactics to improve your sleep, and teaching you how your behaviors, thoughts, feelings, and sleep are linked.
With so many people struggling with disordered sleep, melatonin supplementation is rising. However, there are cases where it’s not a great option, and researchers still need to study the long-term effects. There’s also the issue of a lack of regulation, which can result in incorrect dosages, mislabeling, and low-quality ingredients.
Your doctor is in the best position to recommend whether melatonin is suitable for you. They will suggest better options to ease your sleep woes. They may refer you to a CBTI specialist, suggest lifestyle modifications, or treat underlying conditions causing your sleep difficulties.
Using dietary supplements wisely | NIH: National Center for Complementary and Integrative Health
Missing the mark with melatonin: Finding the best treatment for insomnia | American Academy of Sleep Medicine
What you need to know about dietary supplements | U.S. Food and Drug Administration
Serotonin syndrome (2022)
Study finds that melatonin content of supplements varies widely | American Academy of Sleep Medicine
USP verified mark | USP
Trust in medicines | USP
Clinical practice guideline for the treatment of intrinsic circadian rhythm sleep-wake disorders: Advanced sleep-wake phase disorder (ASWPD), delayed sleep-wake phase disorder (DSWPD), non-24-hour sleep-wake rhythm disorder (N24SWD), and irregular seep-wake rhythm disorder (ISWRD). An update for 2015: An American academy of sleep medicine clinical practice guideline (2015)
Prescription drugs | Health Policy Institute
Melatonin drug interactions | Drugs.com
Victoria is a writer from the UK with a keen interest in health and science. She loves writing about mental health, scientific advancements, and dispelling pseudoscience. When she’s not writing sass-laden articles, she walks her rescue dogs, giggles at anxiety memes, eats chocolate, and absorbs useless knowledge for quiz shows.
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