Melatonin: Does It Actually Work?
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What Is Melatonin?
Melatonin is a hormone your brain makes every night. It tells your body it’s time to sleep. Your pineal gland starts producing it when it gets dark and stops when light hits your eyes.
You can also take it as a supplement. It’s the most popular sleep aid in the United States. About 3.1 million Americans use it regularly.
But here’s what most people get wrong: melatonin isn’t a sleeping pill. It’s a timing signal. It tells your body when to sleep, not how hard to sleep. That distinction matters for understanding what it can and can’t do.
We analyzed 3 major meta-analyses and systematic reviews covering 52 individual studies. Here’s what the data shows.
The Evidence, Claim by Claim
The sections below break down each claim with real numbers from published meta-analyses. Every effect size, confidence interval, and study count comes from peer-reviewed research.
Falling Asleep Faster
This is melatonin’s best-studied use. A 2013 meta-analysis in PLOS ONE pooled 19 randomized controlled trials with 1,683 people. Melatonin reduced time to fall asleep by about 7 minutes (fixed-effects) to 10 minutes (random-effects).
That sounds small. But for someone lying awake for 45 minutes every night, shaving off 10 minutes is meaningful. And the effect is consistent across studies.
A 2024 update by Cruz-Sanabria with 26 trials confirmed the finding. They found the optimal dose is around 4mg, taken 3 hours before your target bedtime. But lower doses (0.5-1mg) still work well.
Jet Lag
This is where melatonin really shines. A Cochrane review (the gold standard for evidence) looked at 10 trials with about 691 travelers.
The number-needed-to-treat was 2. That means for every 2 people who take melatonin for jet lag, 1 will benefit. In medicine, that’s an excellent result. Most drugs have NNTs of 5-20.
Eight out of 10 trials were positive. It works best for eastward travel across 5 or more time zones. Doses between 0.5mg and 5mg all worked. Fast-release tablets beat slow-release.
Sleep Quality
This is where things get less impressive. A 2022 meta-analysis in the Journal of Neurology found melatonin improved sleep quality scores by 1.24 points on the PSQI scale. That’s a real but modest effect.
The results varied a lot between studies (I2 = 80.7%). It worked best in people with metabolic conditions like diabetes (improvement of 2.74 points) and respiratory diseases like COPD (2.20 points). It didn’t help much for mental health conditions or brain diseases.
A 2025 scoping review covering 57 systematic reviews found that 80.9% favored melatonin. But “favored” doesn’t mean “dramatic improvement.” Don’t expect melatonin to transform your sleep quality.
Dosage: Less Is More
This is the biggest thing most people get wrong. Walk into any supplement store and you’ll find melatonin in 5mg and 10mg tablets. Those doses are too high for most people.
Your body makes about 0.1-0.8mg of melatonin per night. A dose of 0.3-0.5mg closely mimics your natural production. Research shows these low doses work just as well as megadoses. Sometimes better.
For falling asleep faster: Start with 0.5-1mg, taken 30-60 minutes before bed.
For jet lag: Take 0.5-5mg at your destination bedtime, starting the day you arrive. Fast-release tablets work better than slow-release.
Timing matters more than dose. Taking melatonin too early or too late reduces its effectiveness. For general sleep, take it 30-60 minutes before bed. For circadian rhythm issues, taking it 3 hours before your target bedtime may work better.
Who Should NOT Take Melatonin
Melatonin is one of the safest supplements out there. But it’s not for everyone.
Don’t take it if you’re pregnant or breastfeeding. There isn’t enough safety data for these groups.
Be careful if you have a seizure disorder. Melatonin may lower the seizure threshold in some people.
Talk to your doctor first if you take blood thinners like warfarin. Melatonin may increase bleeding risk.
Avoid it if you take immunosuppressant drugs. Melatonin can stimulate immune function, which could work against those medications.
If you take fluvoxamine (Luvox), be especially careful. This drug dramatically increases melatonin levels in your body by blocking the enzyme that breaks it down.
The Bottom Line
Melatonin works for two things: falling asleep faster and beating jet lag. The evidence for both is strong. For general sleep quality, the benefits are real but modest.
The most common mistake is taking too much. Start low at 0.3-0.5mg. Only increase if you need to. And remember that melatonin is a timing signal, not a sedative. It works best when you pair it with good sleep habits like a dark room, consistent schedule, and limited screen time before bed.
For jet lag, it’s one of the best-proven interventions available. An NNT of 2 is hard to beat. Pack it for your next long flight.
The Evidence, Claim by Claim
Reduces time to fall asleep ✓ Works
19 studies with about 1,700 people found melatonin helps you fall asleep 7-10 minutes faster. That's not a huge effect, but it's real and consistent. The effect is stronger in people who already have trouble falling asleep. Low doses (0.5-3mg) work about as well as high doses.
Moderate heterogeneity (I2 = 56%) means most studies agree on the direction. No publication bias detected. A 2024 update with 26 trials confirmed the finding and suggested 4mg taken 3 hours before bed as optimal.
View full statistical analysis
Publication Bias Assessment
| Egger's Test | z = —, p = 0.12 | no significant asymmetry detected |
|---|
Subgroup Analysis
| Subgroup | Studies (k) | Effect (g) |
|---|---|---|
| Fixed-effects | 19 | -7.06 |
| Random-effects | 19 | -10.18 |
| Subgroup | Studies (k) | Effect (g) |
|---|---|---|
| Around 4mg |
Prevents jet lag ✓ Works
8 out of 10 trials found melatonin prevents or reduces jet lag symptoms. The NNT is 2, meaning you only need to treat 2 people for 1 to benefit. That's excellent. It works best for eastward travel across 5 or more time zones. Doses between 0.5mg and 5mg all worked. Fast-release tablets beat slow-release.
A number-needed-to-treat of 2 is very impressive for any intervention. This is a Cochrane review, the gold standard for evidence synthesis. The main limitation is that most trials are from the 1990s. But jet lag biology hasn't changed.
View full statistical analysis
Publication Bias Assessment
| Egger's Test | z = —, p = — | not formally assessed |
|---|
Improves overall sleep quality ? Maybe
23 studies found melatonin improves sleep quality scores by about 1.24 points on the PSQI scale. That's a modest improvement. It works best for people with metabolic conditions like diabetes or respiratory problems like COPD. It didn't help much for mental health or brain conditions.
High heterogeneity (I2 = 80.7%) means results vary a lot between studies. The average effect is small. A 2025 scoping review of 57 systematic reviews found 80.9% favored melatonin, but the actual improvements are often modest. Don't expect dramatic changes in sleep quality.
View full statistical analysis
Publication Bias Assessment
| Egger's Test | z = —, p = — | not formally assessed in primary meta-analysis |
|---|
Subgroup Analysis
| Subgroup | Studies (k) | Effect (g) |
|---|---|---|
| Metabolic disorders | -2.74 | |
| Respiratory diseases | -2.2 | |
| Mental disorders | ||
| Neurodegenerative diseases |
Acts as a potent antioxidant ? Maybe
12 trials with 521 people found melatonin increases total antioxidant capacity and reduces markers of oxidative damage. The effects are moderate to large. But nearly all studies used high doses (6-10mg) in people with metabolic diseases like diabetes. We don't know if healthy people get the same benefit at normal doses.
High heterogeneity (I2 = 80.1%) for the main outcome. Three independent meta-analyses all found the same direction of effect, which adds confidence. But the study populations are narrow (mostly metabolic disease patients), doses are high, and no studies measured clinical outcomes like disease prevention. The antioxidant boost is real but its practical meaning is unclear.
View full statistical analysis
Publication Bias Assessment
| Egger's Test | z = —, p = — | not formally assessed |
|---|
Subgroup Analysis
| Subgroup | Studies (k) | Effect (g) |
|---|---|---|
| Total Antioxidant Capacity (TAC) | 12 | 0.76 |
| Glutathione (GSH) | 0.57 | |
| Malondialdehyde (MDA) | -0.79 |
Supports immune system function ? Maybe
31 trials with about 1,500 people found melatonin reduces inflammatory markers like IL-6 and IL-1beta. But there's no meta-analysis on direct immune cell counts or immune function tests. The evidence is really about anti-inflammatory effects, not immune boosting. And some results lost significance when the biggest outliers were removed.
No meta-analysis directly measures immune cell function. The evidence comes from inflammatory marker proxies. Multiple large meta-analyses (up to k=63) consistently show anti-inflammatory effects. But reducing inflammation isn't the same as 'boosting immunity.' The claim is misleading as typically marketed. Melatonin reduces inflammation. It doesn't supercharge your immune system.
View full statistical analysis
Publication Bias Assessment
| Egger's Test | z = —, p = — | not formally assessed |
|---|
Subgroup Analysis
| Subgroup | Studies (k) | Effect (g) |
|---|---|---|
| IL-6 | -3.84 | |
| TNF-alpha | -1.54 | |
| IL-1beta | -1.64 | |
| CRP |
Reduces cancer treatment side effects ? Maybe
A 2025 Cochrane review of 30 trials with 5,093 patients found melatonin may cut cancer-related fatigue in half. That sounds impressive. But the overall evidence quality is very low to moderate. Older meta-analyses showed dramatic benefits for survival and tumor remission, but most of those studies came from one Italian lab with no blinding. When better-designed recent trials tested melatonin, the results were much less exciting.
The Cochrane 2025 review is the gold standard here. It rates most outcomes as very low certainty. The fatigue finding (RR 0.46) has moderate certainty. The dramatic survival benefits from older meta-analyses (Wang 2012, Seely 2012) are likely inflated by bias from unblinded studies dominated by a single research group (Lissoni). Recent well-designed RCTs like Sookprasert 2014 and Zon 2024 found no significant benefits. The truth is probably somewhere in between.
View full statistical analysis
Publication Bias Assessment
| Egger's Test | z = —, p = — | not formally assessed. High concern due to dominance of single research group. |
|---|
Subgroup Analysis
| Subgroup | Studies (k) | Effect (g) |
|---|---|---|
| Fatigue reduction | 0.46 | |
| Tumor remission | 8 | 1.95 |
| 1-year survival | 0.63 |
Slows aging and promotes longevity ✗ No Evidence
There's no human evidence that melatonin extends lifespan or slows aging. This claim comes from animal studies where fruit flies lived about 33% longer with melatonin. But mouse studies are inconsistent, and some showed increased tumor risk. A proxy meta-analysis of 8 trials found melatonin may improve cognitive scores in elderly patients with mild impairment. But that's a long way from 'anti-aging.' One large observational study actually found long-term melatonin users had higher mortality, though that's likely due to sicker people being more likely to use it.
Grade D. No meta-analysis of human longevity or aging outcomes exists. Animal data is mixed. The anti-aging claim relies on extrapolating from antioxidant and anti-inflammatory proxy markers. An AHA 2025 observational analysis found doubled all-cause mortality in long-term users (HR 2.09), though this almost certainly reflects confounding by indication. There's no scientific basis for taking melatonin to live longer.
View full statistical analysis
Publication Bias Assessment
| Egger's Test | z = —, p = — | N/A - no meta-analysis exists |
|---|
Protects brain health and may prevent Alzheimer's ? Maybe
9 studies found melatonin may slightly improve cognitive scores in people with mild Alzheimer's. The effect is about 1.8 points on the MMSE, which is modest but real. However, a Cochrane review found no benefit at all for people with moderate-to-severe dementia. A 2024 network analysis controversially claimed melatonin outperformed new Alzheimer's drugs, but that study had serious limitations. The Alzheimer's Association explicitly says there's no evidence melatonin prevents dementia.
Grade B with major caveats. The positive finding applies only to mild AD with long treatment (>12 weeks). The Cochrane review (gold standard) found nothing for moderate-severe cases. A NIH trial is underway. The 2024 network meta-analysis claiming melatonin beats new AD drugs is provocative but based on tiny studies. Don't take melatonin expecting to prevent Alzheimer's.
View full statistical analysis
Publication Bias Assessment
| Egger's Test | z = —, p = — | not formally assessed |
|---|
Subgroup Analysis
| Subgroup | Studies (k) | Effect (g) |
|---|---|---|
| Mild Alzheimer's (>12 weeks) | 1.89 | |
| Moderate-to-severe dementia | 5 |
| Subgroup | Studies (k) | Effect (g) |
|---|---|---|
| Network MA vs AD drugs | 10 |
Lowers blood pressure ? Maybe
A 2025 mega-analysis of 63 trials with 3,157 people found melatonin lowers systolic blood pressure by about 2.3 mmHg. That's small. For comparison, cutting salt intake drops BP by 5-6 mmHg. The effect was stronger in people with obesity or metabolic syndrome. But here's the catch: controlled-release melatonin lowers BP, while immediate-release may actually raise it. And one study in patients on calcium-channel blockers found melatonin increased BP. The formulation and drug interactions matter a lot.
High heterogeneity (I2 = 69.7%). The largest dedicated hypertension MA (Lee 2022) included only 4 RCTs with 137 patients, and only 1 had low risk of bias. The 2.3 mmHg reduction is statistically significant but clinically marginal. The formulation issue (CR vs IR) is a major concern. Don't take melatonin to treat high blood pressure without medical supervision.
View full statistical analysis
Publication Bias Assessment
| Egger's Test | z = —, p = — | no publication bias detected by Egger's test for BP outcomes |
|---|
Subgroup Analysis
| Subgroup | Studies (k) | Effect (g) |
|---|---|---|
| Controlled-release | 3 | -4.67 |
| Immediate-release | 1 | 6.5 |
| Subgroup | Studies (k) | Effect (g) |
|---|---|---|
| Obese participants | ||
| Metabolic syndrome |
Relieves IBS and GERD symptoms ? Maybe
4 small trials with 115 IBS patients found melatonin at 3mg significantly improved overall IBS severity, pain, and quality of life. The effect size is medium-to-large. All studies used the same dose (3mg at bedtime). The gut makes 400 times more melatonin than the brain, so there's a biological basis for this. But the evidence is thin. Only 4 tiny studies. For GERD, the famous study showing melatonin worked as well as omeprazole combined it with tryptophan and B vitamins, so you can't credit melatonin alone.
Only 4 RCTs with 115 total participants. That's very small. The effect size is promising but needs confirmation. All IBS studies used 3mg at bedtime. The gut melatonin connection is real (enterochromaffin cells produce most of the body's melatonin). But don't replace standard IBS or GERD treatments with melatonin based on this limited evidence. CAUTION: melatonin may worsen gut inflammation in IBD.
View full statistical analysis
Publication Bias Assessment
| Egger's Test | z = —, p = — | not formally assessed due to small number of studies |
|---|
Subgroup Analysis
| Subgroup | Studies (k) | Effect (g) |
|---|---|---|
| IBS (overall severity) | 4 | 0.746 |
| IBS (pain severity) | ||
| Functional dyspepsia | 3 | 4.96 |
| GERD | 1 |
Prevents migraines ✓ Works
9 trials with 788 people found melatonin reduces migraine headache days by about 1.5 per month vs placebo. It also cuts attack duration by 5 hours, reduces pain severity, and lowers analgesic use. Patients on melatonin were 38% more likely to see their migraines cut in half. A large network meta-analysis ranked melatonin 3mg immediate-release as the most preferred treatment overall when balancing efficacy, side effects, and dropout rates. It's less powerful than amitriptyline but much better tolerated.
Low heterogeneity (I2 = 0%) for most outcomes, which is excellent. A 2020 network meta-analysis with 25 RCTs and 4,499 patients ranked melatonin 3mg IR as the top choice considering efficacy and tolerability. Formulation is critical: 3mg immediate-release works, 2mg sustained-release doesn't. This is a legitimate, evidence-based use of melatonin that most people don't know about.
View full statistical analysis
Publication Bias Assessment
| Egger's Test | z = —, p = — | fewer than 10 studies per comparison, Egger's test not feasible |
|---|
Subgroup Analysis
| Subgroup | Studies (k) | Effect (g) |
|---|---|---|
| Immediate-release 3mg | -1.71 | |
| Sustained-release 2mg | 1 |
| Subgroup | Studies (k) | Effect (g) |
|---|---|---|
| Melatonin vs amitriptyline (adults) | 1 | |
| Melatonin vs amitriptyline (children) | 2 |
Dosage Guide
| Effective Range | 0.5-3mg |
|---|---|
| Optimal Dose | 0.5-1mg for sleep onset, 3-5mg for jet lag |
| Best Form | Immediate-release tablet or sublingual |
| Timing | 30-60 minutes before bed for sleep, 3 hours before target bedtime for jet lag |
| Time to Effect | 30-60 minutes |
| Cycling | Not typically needed, but periodic breaks are reasonable |
| Notes | Less is more with melatonin. Your body makes about 0.1-0.8mg per night. Doses of 0.3-0.5mg closely mimic natural levels. Higher doses (5-10mg) aren't more effective and may cause morning grogginess. Fast-release works better than slow-release for jet lag. |
Don't Take If
- Pregnancy and breastfeeding (insufficient safety data)
- Seizure disorders (may lower seizure threshold)
- Autoimmune conditions (may stimulate immune function)
- Children (use only under medical supervision)
Drug Interactions
| Medication | Risk | Why |
|---|---|---|
| Blood thinners (warfarin, heparin) | moderate | May increase bleeding risk by affecting platelet aggregation |
| Immunosuppressants | moderate | Melatonin may stimulate immune function, counteracting immunosuppressive drugs |
| Diabetes medications | moderate | May affect blood sugar levels and insulin sensitivity |
| Sedatives and benzodiazepines | low | Additive sedation possible, though melatonin's sedative effect is mild |
| Fluvoxamine (Luvox) | high | Fluvoxamine strongly inhibits CYP1A2, dramatically increasing melatonin levels |
Possible Side Effects
- Morning grogginess at high doses
- Vivid dreams or nightmares
- Headache (uncommon)
- Mild dizziness
- Nausea at very high doses
What to Buy
Disclosure: Links below are affiliate links. We earn a commission if you buy. We never recommend products that fail our evidence checks.
Life Extension Melatonin 0.3mg
Low dose (0.3mg) matches physiological levels, third-party tested, affordable
Frequently Asked Questions
Does melatonin help you fall asleep faster?
Yes. 19 randomized controlled trials with about 1,700 people found melatonin cuts sleep onset time by 7-10 minutes on average. The effect is stronger if you already struggle to fall asleep.
What's the best melatonin dose for sleep?
Lower than you think. Most people take 5-10mg, but research shows 0.5-1mg works just as well. Your body only makes about 0.1-0.8mg per night. Start with 0.3-0.5mg and increase only if needed.
Does melatonin work for jet lag?
Yes, and this is one of its strongest uses. A Cochrane review found 8 out of 10 trials were positive, with a number-needed-to-treat of 2. Take 0.5-5mg at your destination bedtime, starting the day you arrive.
Is melatonin safe for long-term use?
Short-term safety is well established. Long-term data is more limited but generally reassuring. It's one of the safest sleep supplements available. Avoid it if you're pregnant, have seizure disorders, or take blood thinners or immunosuppressants.
Why does melatonin give me weird dreams?
Melatonin increases REM sleep, which is the sleep stage where vivid dreams happen. This is more common at higher doses. Try lowering your dose to 0.3-0.5mg. If vivid dreams persist, take it earlier in the evening.