Melatonin: What It Is, How It Works, and Should You Take It?

Walk into any pharmacy or grocery store and you’ll find an entire shelf dedicated to melatonin. Gummies, tablets, sprays, drops, even melatonin-infused chocolates. Sales in the United States alone have grown from $285 million in 2016 to over $1.8 billion by 2024. It’s become the default answer to “I can’t sleep” — pop a melatonin and hope for the best.

But most people taking melatonin don’t fully understand what it is, how it works, or whether they’re using it correctly. And the gap between what melatonin actually does and what people expect it to do is enormous.

What Melatonin Actually Is

Melatonin is not a sleeping pill. This is the single most important thing to understand, and the thing most people get wrong.

Melatonin is a hormone produced naturally by the pineal gland, a pea-sized structure deep in your brain. Its primary job isn’t to make you sleep — it’s to signal to your body that darkness has arrived and sleep is approaching. Think of it as a biological “sunset signal” rather than an “off switch.”

Every evening, as light levels drop, your pineal gland begins releasing melatonin into your bloodstream. Levels rise gradually over two to three hours, peaking in the middle of the night (typically between 2-4 AM), then declining toward morning as light exposure increases. This cycle is tightly linked to your circadian rhythm — the internal 24-hour clock that governs not just sleep, but body temperature, hormone release, digestion, and dozens of other processes.

Melatonin doesn’t knock you out. It opens the “sleep gate” — lowering your core body temperature slightly, reducing alertness, and creating the physiological conditions that make sleep possible. Whether you actually fall asleep depends on many other factors: your environment, stress levels, caffeine intake, and sleep habits.

How Light Controls Your Melatonin

Your body’s melatonin production is exquisitely sensitive to light — particularly blue light in the 460-480 nanometer wavelength range. This is the same wavelength emitted abundantly by phone screens, computer monitors, and LED lighting.

When light hits specialized cells in your retina called intrinsically photosensitive retinal ganglion cells (ipRGCs), they send a signal directly to the suprachiasmatic nucleus (SCN) — your brain’s master clock. The SCN then tells the pineal gland to suppress melatonin production. Bright light in the evening can delay melatonin onset by 90 minutes or more.

A 2014 study published in Proceedings of the National Academy of Sciences compared participants who read from an iPad before bed to those who read a printed book. The iPad readers showed suppressed melatonin levels, delayed melatonin onset by an average of 1.5 hours, reduced REM sleep, and reported feeling sleepier the next morning — even after eight hours in bed.

This is why sleep hygiene advice consistently emphasizes reducing screen time before bed. It’s not just about mental stimulation. It’s about a direct hormonal effect on your body’s sleep-timing system.

Morning light exposure has the opposite effect. Bright light in the first hour after waking suppresses any remaining melatonin, advances your circadian clock, and sets up a stronger melatonin release the following evening. Getting outside in natural daylight — even on a cloudy day — is one of the most effective things you can do for your sleep, and it costs nothing.

Do Melatonin Supplements Actually Work?

The honest answer: it depends on what you’re using them for.

Jet lag: Yes. This is melatonin’s strongest use case. A Cochrane review of 10 randomized trials found that melatonin significantly reduced jet lag symptoms when taken close to the target bedtime at the destination. It’s particularly effective for eastward travel (where you need to advance your sleep schedule) and for crossing five or more time zones. Doses of 0.5-5 mg were similarly effective.

Delayed sleep phase: Yes. If your natural sleep timing is shifted too late — you can’t fall asleep until 2 or 3 AM but sleep fine once you do — low-dose melatonin taken 3-5 hours before your desired bedtime can help advance your circadian clock. This is a timing intervention, not a sedation one.

Shift work: Moderately helpful. Night shift workers who need to sleep during the day can benefit from melatonin taken before their daytime sleep period. It helps signal “nighttime” to a body that’s receiving conflicting light cues. Results are mixed but generally positive.

General insomnia: Mixed at best. Here’s where expectations diverge from reality. For people who have trouble sleeping due to stress, anxiety, pain, or poor sleep habits, melatonin supplements show modest benefits at best. A meta-analysis in PLOS ONE found that melatonin reduced the time to fall asleep by an average of only 7 minutes and increased total sleep time by about 8 minutes. Statistically significant, but not the dramatic effect most people expect.

The reason is straightforward: if your insomnia isn’t caused by a melatonin deficiency or a circadian timing problem, adding more melatonin won’t fix it. It’s like pouring more gasoline into a car that has a flat tire. The fuel isn’t the issue.

Proper Dosing: Less Is More

This is where most people go wrong. Walk into a store and you’ll find melatonin supplements ranging from 1 mg to 10 mg, with some brands pushing 12 or even 20 mg. The assumption is that more equals stronger equals better sleep.

The research says the opposite.

Your body’s natural melatonin production peaks at levels equivalent to roughly 0.1-0.3 mg in the bloodstream. A 2001 study from MIT found that the most effective supplemental dose for improving sleep was 0.3 mg — a fraction of what most commercial products contain. Doses of 3 mg and above raised blood melatonin levels to 10-20 times the natural physiological range, which can actually desensitize melatonin receptors over time and reduce the supplement’s effectiveness.

Dr. Richard Wurtman, the MIT neuroscientist who led that research, has been vocal about the problem: “The doses available in stores are way too high. People are taking 10 times or more what they should be taking.”

The practical recommendation from most sleep researchers is to start with 0.5 mg. If that doesn’t help after a week, try 1 mg. Go up to 3 mg only if lower doses are ineffective. If 3 mg doesn’t work, more won’t either — and you should look at other factors affecting your sleep.

Timing Matters as Much as Dose

Taking melatonin at the wrong time can actually make your sleep worse.

For falling asleep at a normal bedtime, take melatonin 1-2 hours before your desired sleep time. This mimics the natural rise of melatonin that occurs in the evening. Taking it right at bedtime is too late — by the time it’s absorbed and reaches effective levels, you’ve already been lying awake for 30-45 minutes.

For shifting your sleep schedule earlier (delayed sleep phase), take a low dose 3-5 hours before your current natural sleep time. This leverages melatonin’s chronobiotic effect — its ability to shift the timing of your circadian clock.

For jet lag, take melatonin at the target bedtime of your destination, starting the first night you arrive. Some travelers begin one day before departure.

Using a sleep calculator can help you determine your ideal bedtime and work backward to find the optimal melatonin timing.

Side Effects and Concerns

Melatonin is generally well-tolerated in adults at appropriate doses. But “generally safe” doesn’t mean “no side effects.”

Common side effects include morning grogginess (especially at higher doses), headaches, dizziness, and nausea. Some people report vivid dreams or nightmares, likely because melatonin can increase REM sleep duration. These effects are typically dose-dependent — another reason to start low.

A more subtle concern is quality control. In the United States, melatonin is classified as a dietary supplement, not a drug, which means it’s not subject to the same manufacturing standards as prescription medications. A 2017 study in the Journal of Clinical Sleep Medicine tested 31 melatonin supplements and found that actual melatonin content ranged from 83% less to 478% more than what the label stated. Some products also contained serotonin, a neurotransmitter that shouldn’t be in an over-the-counter supplement.

If you choose to take melatonin, buy from reputable brands that use third-party testing (look for USP, NSF, or ConsumerLab verification on the label).

Who Should Avoid Melatonin

Melatonin isn’t appropriate for everyone. The following groups should consult a doctor before using it:

Children and adolescents. While melatonin is increasingly given to children with sleep difficulties, long-term safety data in developing brains is limited. The body’s melatonin system is still maturing during childhood, and supplementation may interfere with that process. Some European countries require a prescription for melatonin for this reason.

Pregnant or breastfeeding women. Melatonin crosses the placenta and is present in breast milk. Its effects on fetal and infant development aren’t well understood.

People on blood thinners, immunosuppressants, or diabetes medications. Melatonin can interact with several drug classes. It may increase the effect of blood thinners, affect immune function, and influence blood sugar levels.

People with autoimmune conditions. Melatonin has immunomodulatory effects — it can stimulate certain immune responses. For people with autoimmune diseases, this could theoretically worsen symptoms.

Natural Ways to Boost Melatonin Production

Before reaching for a supplement, consider that your body already makes melatonin — it just needs the right conditions to do so effectively.

Get bright light exposure in the morning. Fifteen to thirty minutes of outdoor light within an hour of waking sets your circadian clock and primes a stronger melatonin release that evening. This is the single most effective natural intervention.

Dim the lights in the evening. Starting two hours before bed, reduce overhead lighting and switch to warm, dim light sources. Your pineal gland can’t distinguish between sunlight and a bright ceiling fixture — both suppress melatonin.

Reduce screen exposure before bed. If you must use screens in the evening, enable night mode (which reduces blue light emission) and keep the screen at arm’s length. Better yet, switch to a book, podcast, or conversation for the last hour before bed.

Keep a consistent sleep schedule. Your melatonin release timing is anchored to your habitual sleep schedule. Irregular bedtimes confuse the system. Use a sleep calculator to find your ideal bedtime and stick to it — even on weekends.

Eat melatonin-supporting foods. Tart cherries, walnuts, milk, fatty fish, and rice contain either melatonin or its precursor tryptophan. A 2012 study found that drinking tart cherry juice twice daily increased sleep time by an average of 84 minutes. These aren’t miracle foods, but they support the body’s natural production.

Keep your bedroom cool and dark. Melatonin production is enhanced by darkness and slightly cool temperatures. A room temperature of 65-68°F (18-20°C) and blackout curtains or a sleep mask create the ideal environment.

The Bottom Line

Melatonin supplements have a legitimate place in sleep medicine — primarily for jet lag, circadian rhythm disorders, and short-term schedule adjustments. For these uses, they’re effective, safe, and well-supported by research.

But melatonin is not a universal sleep fix. If your sleep problems stem from stress, poor habits, an uncomfortable environment, or an underlying medical condition, a melatonin pill won’t solve them. And taking high doses nightly as a long-term strategy is neither well-supported by evidence nor recommended by most sleep specialists.

The best approach is to optimize your body’s own melatonin production first — through light management, consistent scheduling, and good sleep hygiene. If you still need help, use melatonin strategically: low dose, proper timing, and for a specific purpose. And if sleep problems persist, talk to a doctor. Sometimes the issue isn’t melatonin at all — it’s something that needs a different kind of attention.