What is Melatonin?

What is Melatonin?

Melatonin is the hormone your own pineal gland releases every night to tell your brain and body that it is dark and time to wind down. Levels start climbing roughly two hours before your normal bedtime, peak in the middle of the night, and fall again near your wake time, tracking the light-dark cycle your eyes detect through the retina.

As a supplement, melatonin is a synthetic or lab-produced copy of that same molecule, sold over the counter in the United States as tablets, capsules, gummies, and liquid drops ranging from about 0.3 mg to 10 mg. It is not a sedative in the way a sleeping pill is. A benzodiazepine or Z-drug forces the central nervous system down; melatonin instead sends a timing signal that nudges your internal clock, so its effect on how fast you fall asleep is real but modest, and its bigger job is shifting when your clock says sleep now.

That distinction is why melatonin helps most with problems of timing, jet lag, shift work, delayed sleep-wake phase disorder, rather than with chronic insomnia in someone whose clock is already set correctly. Use has climbed sharply: reported melatonin supplement use among U.S. adults rose about 425% over two decades, and the size of the average dose has grown too, with many people now taking more than 5 mg despite no evidence that doing so works better. Because it is regulated as a dietary supplement rather than a drug, potency on the label is not guaranteed, and gummies in particular have tested far off their stated dose.

How it works

Melatonin works by binding to MT1 and MT2 receptors concentrated in the suprachiasmatic nucleus (SCN), the master clock sitting in your hypothalamus, plus receptors in the retina and elsewhere in the body. The pathway starts at the eye: specialized retinal cells detect falling light and send that signal up the retinohypothalamic tract to the SCN, which then tells the pineal gland to start secreting melatonin, a process suppressed almost instantly by bright light, especially blue wavelengths from screens and overhead lighting.

Once melatonin binds MT1 receptors it promotes sleep onset and dampens the SCN's wake-promoting signal; MT2 binding is more involved in shifting the phase of the clock itself, which is the mechanism jet lag and shift-work protocols rely on. In the body, melatonin has a short elimination half-life of roughly one to two hours, and about 90% of a dose is cleared by the liver enzyme CYP1A2, so blood levels rise and fall quickly rather than lingering into the next day at typical doses.

Timing relative to your own dim-light melatonin onset, the point in the evening your pineal gland naturally starts secreting, matters more than the clock hour printed on the bottle. A 2024 dose-response meta-analysis of 26 randomized trials found that a 4 mg dose taken about three hours before bedtime outperformed the common default of 2 mg taken thirty minutes before bed, for both cutting the time to fall asleep and increasing total sleep time. That is the opposite of what most over-the-counter labels imply, and it explains why casual right-before-bed dosing at 1 to 3 mg produces a real but modest effect, a mean reduction in sleep onset latency of about seven minutes across pooled trial data, while properly timed, circadian-focused dosing produces a bigger shift in when sleep actually happens.

The scale

Melatonin has no strength equation like 1RM, but decades of dose-response trials give a practical dosing table. Effect climbs with dose up to about 4 mg/day; above 5 mg, side effects rise without extra sleep benefit.

How to apply it

• Eastward jet lag (phase advance): Take 0.5-5 mg near the target bedtime at your destination, starting the evening you arrive, and continue for 2 to 4 nights. Eastward travel needs your clock to move earlier, the direction melatonin shifts most reliably.
• Westward jet lag (phase delay): Melatonin helps less here because your clock already wants to delay; morning bright light and a later bedtime do more of the work. A small evening dose (0.5-3 mg) at the new local bedtime is a reasonable add-on, not the main fix.
• Night-shift or rotating-shift work: Take 1-3 mg shortly before your daytime sleep period after a night shift, combined with blackout curtains and dark sunglasses on the drive home, so your body learns to treat that block as its main sleep.
• Delayed sleep-wake phase disorder: The counterintuitive case: a low dose (0.5-1 mg) taken 4 to 6 hours before your current natural sleep time, in the late afternoon or early evening, phase-advances the clock better than dosing right at bedtime.
• Occasional trouble falling asleep: For a night when your own clock is fine but you cannot switch off, 1-3 mg taken 30 to 60 minutes before bed produces a modest reduction in the time it takes to fall asleep, on the order of a few minutes.
• Evening recovery dosing for athletes: Emerging trials use 6 mg roughly 30 minutes before sleep on nights after hard training, timed more than 6 hours after the session, to raise perceived recovery and next-day repeated-sprint output; evidence is still early and doses this high increase grogginess risk.

Types

Worked example

You fly from New York to London, a 5-hour eastward time shift, arriving at 8 a.m. local time. Eastward travel is the direction melatonin's phase-advancing effect works best for, so here is a simple three-night protocol layered onto light exposure.

Most travelers need about one day of adjustment per time zone crossed. Melatonin shortens that, it does not erase it, and it works better paired with morning light than used alone.

Melatonin vs prescription sleep medication (Z-drugs)

Melatonin is the gentler, timing-focused tool; it will not replicate a Z-drug's sedation, and it is not meant to. Try CBT-I or see a clinician before either one becomes a nightly habit for chronic insomnia.

By goal

• Jet-lagged or shift-working: Use melatonin for what it's built for: shifting when your clock says sleep. Time doses relative to your destination or shift schedule, not the clock hour you're used to, and pair every dose with matched light exposure.
• Occasional poor sleepers: Keep it simple: 1-3 mg, 30-60 minutes before bed, on nights you need it. Fix light exposure and a consistent wind-down routine first; melatonin is a small assist, not a fix for chronic bad sleep habits.
• Athletes and heavy trainees: If you use it for recovery, keep the dose modest (1-3 mg) unless following a supervised protocol, take it more than 6 hours before you need to be alert, and judge it by perceived recovery and next session's output, not by how quickly you fall asleep.

Common misconceptions

• "Melatonin knocks you out like a sleeping pill." It is a timing hormone, not a sedative-hypnotic. Pooled trial data show it shortens time to fall asleep by roughly 7 minutes on average, a real but modest effect nowhere near a benzodiazepine or Z-drug's sedation.
• "More melatonin works better." A 2024 dose-response meta-analysis found effects on sleep onset and total sleep time climb up to about 4 mg/day and flatten above that; doses over 5 mg mostly add grogginess and headache without added benefit.
• "Take it right before bed no matter what you're using it for." That's correct for occasional sleep-onset trouble, but for delayed sleep-wake phase disorder the effective timing is 4 to 6 hours before your natural sleep time, in the late afternoon, because you're shifting the clock, not sedating yourself.
• "It's natural, so any dose is safe and well regulated." Melatonin is sold as an unregulated dietary supplement in the U.S., not an FDA-approved drug. Independent testing has found gummies containing anywhere from 74% to 347% of their labeled dose, and long-term daily-use safety data are still limited.
• "Melatonin fixes chronic insomnia." Major sleep-medicine guidelines from the American Academy of Sleep Medicine and American College of Physicians say the evidence does not support melatonin for chronic insomnia; cognitive behavioral therapy for insomnia (CBT-I) is the recommended first-line treatment instead.

Related terms

Melatonin FAQ

What does melatonin do for sleep?

Melatonin is the hormone your pineal gland releases at night to signal darkness and set the timing of your sleep-wake cycle. As a supplement it works mainly as a timing cue that shifts when your body is ready for sleep, and only secondarily as a mild sleep aid that modestly shortens how long it takes you to fall asleep.

How much melatonin should I take?

Most adults do best starting at 0.5 to 1 mg, 30 to 60 minutes before bed, and moving up to 1-3 mg if needed. Research shows effects peak around 4 mg/day; doses above 5 mg rarely help more and raise the odds of grogginess, headache, or vivid dreams.

When should I take melatonin before bed?

For occasional sleep-onset trouble, take it 30 to 60 minutes before your target bedtime. For circadian problems like delayed sleep-wake phase disorder, take a low dose 4 to 6 hours before your natural sleep time instead, since you're shifting the clock, not sedating yourself.

Is it safe to take melatonin every night?

Short-term nightly use appears safe for most healthy adults, with mild side effects like headache or daytime drowsiness in some people. Long-term daily safety data are still limited, so most sleep specialists suggest using it for a defined stretch, jet lag or a shift-work rotation, rather than indefinitely.

Does melatonin help you fall asleep or stay asleep?

It has more effect on falling asleep than staying asleep. Pooled trial data show it cuts sleep onset latency by about 7 minutes and adds roughly 8 minutes to total sleep time on average, real but modest changes, smaller than a prescription sleep medication produces.

Can you take too much melatonin?

Yes, in the sense that more is not better past about 4 mg a day; benefits plateau and side effects like next-day grogginess, headache, and abdominal discomfort become more common. Because supplement labels are unregulated, gummies in particular have tested well above their stated dose, so overshooting is easy to do by accident.

Does melatonin help with muscle recovery for athletes?

Early placebo-controlled trials found 6 mg taken in the evening after hard training improved perceived recovery and next-day repeated-sprint performance in trained athletes, alongside melatonin's known antioxidant and anti-inflammatory activity. The evidence base is still small, so treat it as a recovery add-on, not a replacement for sleep and nutrition.

Is melatonin the same as a sleeping pill?

No. Prescription sleeping pills like zolpidem sedate the central nervous system directly through GABA receptors. Melatonin binds different receptors, MT1 and MT2, and acts as a timing signal to your internal clock, which is why its effect on falling asleep is real but much smaller than a Z-drug's.

Does melatonin cause grogginess the next day?

At typical low-to-moderate doses (0.5-3 mg) grogginess is uncommon because melatonin's elimination half-life is only about 1 to 2 hours. Higher doses, especially above 5 mg, and gummies that test far over their labeled strength are the more common sources of next-day drowsiness.

Can melatonin help with jet lag?

Yes, it's one of the better-supported uses. Taken near the target bedtime at your destination for a few nights, melatonin helps reset your circadian clock faster, especially for eastward travel. Pairing it with morning light exposure at the new location speeds the adjustment further.

References

1. Melatonin. StatPearls, NCBI Bookshelf, 2024
2. Melatonin: What You Need To Know. National Center for Complementary and Integrative Health (NCCIH)
3. Melatonin: What It Is, What It Does & How It Works. Cleveland Clinic
4. Ferracioli-Oda E, Qawasmi A, Bloch MH. Meta-Analysis: Melatonin for the Treatment of Primary Sleep Disorders. PLoS ONE, 2013. PMC3656905
5. Cruz-Sanabria F, et al. Optimizing the Time and Dose of Melatonin as a Sleep-Promoting Drug: A Systematic Review of Randomized Controlled Trials and Dose-Response Meta-Analysis. Journal of Pineal Research, 2024;76(5):e12985
6. Take melatonin supplements for sleep? Check your dosage. Harvard Health Publishing
7. Melatonin. Wikipedia
8. Mahdi N, et al. Melatonin Supplementation Enhances Next-Day High-Intensity Exercise Performance and Recovery in Trained Males: A Placebo-Controlled Crossover Study. Sports (Basel), 2025;13(6). PMC12197174