Supplement

Melatonin

Melatonin is a hormone your brain releases in the evening that tells your body it is time to sleep and helps set your internal clock. Most people look at it for sleep and insomnia, and the evidence is strong: in five studies, insomnia symptoms improved, including in older adults and in children who struggled to fall asleep. Those studies were fairly small, though, with 259 people in total, so the findings say more about who was studied than about everyone.

Sources: PMID 19584739; PMID 21340475

Updated 30 September 2026
How we grade
38 studies cited

Best evidence: Grade A
Conditions studied: 30
Outcomes: 141
Graded outcomes: 23148

Evidence by condition

Strong
Moderate
Limited
Very limited

30 conditions

Insomnia

Insomnia: outcomes studied for Melatonin
Grade	Outcome	Effect	Size	Studies	People
	Insomnia Signs and Symptoms Large Improvement	Improves (the measure goes down)	Large effect	5 studies	259 people
Studies that measured insomnia signs and symptoms The effect of prolonged-release melatonin on sleep measures and psychomotor performance in elderly patients with insomniaInt Clin Psychopharmacol · PMID 19584739 Evaluation of sleep, puberty and mental health in children with long-term melatonin treatment for chronic idiopathic childhood sleep onset insomniaPsychopharmacology · PMID 21340475 Prolonged-release melatonin improves sleep quality and morning alertness in insomnia patients aged 55 years and older and has no withdrawal effectsJ Sleep Res · PMID 18036082 Effect of melatonin on insomnia and daytime sleepiness, in patients with obstructive sleep apnea and insomnia (COMISA): A randomized double-blinded placebo-controlled trial.J Pharm Health Care Sci · PMID 38816846 Prophylaxis of migraine with melatonin: a randomized controlled trialNeurology · PMID 20975054
	Sleep Quality	Improves (the measure goes up)			211 people

Irritable Bowel Syndrome (IBS)

Irritable Bowel Syndrome (IBS): outcomes studied for Melatonin
Grade	Outcome	Effect	Size	Studies	People
	Abdominal Pain Moderate Improvement	Improves (the measure goes down)	Moderate effect		115 people
	Irritable Bowel Syndrome Symptoms	Improves (the measure goes down)		1 study	115 people
Studies that measured irritable bowel syndrome symptoms The efficacy of exogenous melatonin supplement in ameliorating irritable bowel syndrome severity: A meta-analysis of randomized controlled trials.J Formos Med Assoc · PMID 36257872
	Quality of Life	Improves (the measure goes up)			115 people

Body Composition

Blood Pressure: improves
Body Mass Index (BMI): improves
Hip Circumference: improves

Body Composition: outcomes studied for Melatonin
Grade	Outcome	Effect	Size	Studies	People
	Blood Pressure Small Improvement	Improves (the measure goes down)	Small effect	5 studies	1,543 people
Studies that measured blood pressure Effect of melatonin supplementation on body composition and blood pressure in adults: A systematic review and Dose-Response meta-analysis of randomized controlled trial.Heliyon · PMID 39113944 Effects of melatonin on vascular reactivity, catecholamine levels, and blood pressure in healthy menAm J Cardiol · PMID 10235107 Acute effects of melatonin administration on cardiovascular autonomic regulation in healthy menAm Heart J · PMID 11320384 Influences of melatonin administration on the circulation of womenAm J Physiol · PMID 9486289 Effects of Melatonin Supplementation On Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.Horm Metab Res · PMID 30861561
	Body Mass Index (BMI)	Improves (the measure goes down)			1,543 people
	Hip Circumference	Improves (the measure goes down)			1,543 people
	Waist circumference	Improves (the measure goes down)			1,543 people
	Weight	Improves (the measure goes down)			1,543 people

Tinnitus

Sleep Quality: improves
Tinnitus Symptoms: improves

Tinnitus: outcomes studied for Melatonin
Grade	Outcome	Effect	Size	Studies	People
	Sleep Quality Small Improvement	Improves (the measure goes up)	Small effect		85 people
	Tinnitus Symptoms	Improves (the measure goes down)		4 studies	217 people
Studies that measured tinnitus symptoms Treatment of central and sensorineural tinnitus with orally administered Melatonin and Sulodexide: personal experience from a randomized controlled studyActa Otorhinolaryngol Ital · PMID 20111618 Melatonin: can it stop the ringing?Ann Otol Rhinol Laryngol · PMID 21859051 The effects of melatonin on tinnitus and sleepOtolaryngol Head Neck Surg · PMID 16455366 Effect of melatonin on tinnitusLaryngoscope · PMID 9504599

Depression

Depression Symptoms: improves
Serum BDNF: improves

Depression: outcomes studied for Melatonin
Grade	Outcome	Effect	Size	Studies	People
	Depression Symptoms Small Improvement	Improves (the measure goes down)	Small effect		2,070 people
	Serum BDNF	Improves (the measure goes up)		1 study	2,070 people
Studies that measured serum bdnf Effects of melatonin supplementation on BDNF concentrations and depression: A systematic review and meta-analysis of randomized controlled trials.Behav Brain Res · PMID 36049659

Migraine Headache

Insomnia Signs and Symptoms: improves
Migraine Frequency: improves
Migraine Duration: improves

Migraine Headache: outcomes studied for Melatonin
Grade	Outcome	Effect	Size	Studies	People
	Insomnia Signs and Symptoms Large Improvement	Improves (the measure goes down)	Large effect	5 studies	48 people
Studies that measured insomnia signs and symptoms The effect of prolonged-release melatonin on sleep measures and psychomotor performance in elderly patients with insomniaInt Clin Psychopharmacol · PMID 19584739 Evaluation of sleep, puberty and mental health in children with long-term melatonin treatment for chronic idiopathic childhood sleep onset insomniaPsychopharmacology · PMID 21340475 Prolonged-release melatonin improves sleep quality and morning alertness in insomnia patients aged 55 years and older and has no withdrawal effectsJ Sleep Res · PMID 18036082 Effect of melatonin on insomnia and daytime sleepiness, in patients with obstructive sleep apnea and insomnia (COMISA): A randomized double-blinded placebo-controlled trial.J Pharm Health Care Sci · PMID 38816846 Prophylaxis of migraine with melatonin: a randomized controlled trialNeurology · PMID 20975054
	Migraine Frequency	Improves (the measure goes down)		1 study	244 people
Studies that measured migraine frequency Randomised clinical trial comparing melatonin 3 mg, amitriptyline 25 mg and placebo for migraine prevention.J Neurol Neurosurg Psychiatry · PMID 27165014
	Migraine Duration	Improves (the measure goes down)			196 people
	Migraine Severity	Improves (the measure goes down)			196 people
	Sleep Quality	Improves (the measure goes up)			48 people

Sleep Health

Insomnia Signs and Symptoms: improves
Migraine Frequency: improves
Sleep Latency: improves

Sleep Health: outcomes studied for Melatonin
Grade	Outcome	Effect	Size	Studies	People
	Insomnia Signs and Symptoms Large Improvement	Improves (the measure goes down)	Large effect	5 studies	48 people
Studies that measured insomnia signs and symptoms The effect of prolonged-release melatonin on sleep measures and psychomotor performance in elderly patients with insomniaInt Clin Psychopharmacol · PMID 19584739 Evaluation of sleep, puberty and mental health in children with long-term melatonin treatment for chronic idiopathic childhood sleep onset insomniaPsychopharmacology · PMID 21340475 Prolonged-release melatonin improves sleep quality and morning alertness in insomnia patients aged 55 years and older and has no withdrawal effectsJ Sleep Res · PMID 18036082 Effect of melatonin on insomnia and daytime sleepiness, in patients with obstructive sleep apnea and insomnia (COMISA): A randomized double-blinded placebo-controlled trial.J Pharm Health Care Sci · PMID 38816846 Prophylaxis of migraine with melatonin: a randomized controlled trialNeurology · PMID 20975054
	Migraine Frequency	Improves (the measure goes down)		1 study	48 people
Studies that measured migraine frequency Randomised clinical trial comparing melatonin 3 mg, amitriptyline 25 mg and placebo for migraine prevention.J Neurol Neurosurg Psychiatry · PMID 27165014
	Sleep Latency	Improves (the measure goes down)		1 study	498 people
Studies that measured sleep latency Efficacy on sleep parameters and tolerability of melatonin in individuals with sleep or mental disorders: A systematic review and meta-analysis.Neurosci Biobehav Rev · PMID 35691474
	Sleep Duration	Improves (the measure goes up)			480 people
	Sleep Quality	Improves (the measure goes up)			48 people

Cognitive Improvement

Insomnia Signs and Symptoms: improves
Sleep Quality: improves

Cognitive Improvement: outcomes studied for Melatonin
Grade	Outcome	Effect	Size	Studies	People
	Insomnia Signs and Symptoms Large Improvement	Improves (the measure goes down)	Large effect	5 studies	40 people
Studies that measured insomnia signs and symptoms The effect of prolonged-release melatonin on sleep measures and psychomotor performance in elderly patients with insomniaInt Clin Psychopharmacol · PMID 19584739 Evaluation of sleep, puberty and mental health in children with long-term melatonin treatment for chronic idiopathic childhood sleep onset insomniaPsychopharmacology · PMID 21340475 Prolonged-release melatonin improves sleep quality and morning alertness in insomnia patients aged 55 years and older and has no withdrawal effectsJ Sleep Res · PMID 18036082 Effect of melatonin on insomnia and daytime sleepiness, in patients with obstructive sleep apnea and insomnia (COMISA): A randomized double-blinded placebo-controlled trial.J Pharm Health Care Sci · PMID 38816846 Prophylaxis of migraine with melatonin: a randomized controlled trialNeurology · PMID 20975054
	Sleep Quality	Improves (the measure goes up)			40 people

Obstructive Sleep Apnea (OSA)

Insomnia Signs and Symptoms: improves
Sleep Quality: improves

Obstructive Sleep Apnea (OSA): outcomes studied for Melatonin
Grade	Outcome	Effect	Size	Studies	People
	Insomnia Signs and Symptoms Large Improvement	Improves (the measure goes down)	Large effect	5 studies	1 person
Studies that measured insomnia signs and symptoms The effect of prolonged-release melatonin on sleep measures and psychomotor performance in elderly patients with insomniaInt Clin Psychopharmacol · PMID 19584739 Evaluation of sleep, puberty and mental health in children with long-term melatonin treatment for chronic idiopathic childhood sleep onset insomniaPsychopharmacology · PMID 21340475 Prolonged-release melatonin improves sleep quality and morning alertness in insomnia patients aged 55 years and older and has no withdrawal effectsJ Sleep Res · PMID 18036082 Effect of melatonin on insomnia and daytime sleepiness, in patients with obstructive sleep apnea and insomnia (COMISA): A randomized double-blinded placebo-controlled trial.J Pharm Health Care Sci · PMID 38816846 Prophylaxis of migraine with melatonin: a randomized controlled trialNeurology · PMID 20975054
	Sleep Quality	Improves (the measure goes up)			1 person

High Blood Pressure

Anti-Oxidant Enzyme Profile: improves
Adrenaline
Blood Pressure: improves

High Blood Pressure: outcomes studied for Melatonin
Grade	Outcome	Effect	Size	Studies	People
	Anti-Oxidant Enzyme Profile Small Increase	Improves (the measure goes up)	Small effect	1 study	30 people
Studies that measured anti-oxidant enzyme profile Melatonin treatment improves blood pressure, lipid profile, and parameters of oxidative stress in patients with metabolic syndromeJ Pineal Res · PMID 21138476
	Adrenaline No effect		NoneNo effect		17 people
	Blood Pressure	Improves (the measure goes down)		5 studies	52 people
Studies that measured blood pressure Effect of melatonin supplementation on body composition and blood pressure in adults: A systematic review and Dose-Response meta-analysis of randomized controlled trial.Heliyon · PMID 39113944 Effects of melatonin on vascular reactivity, catecholamine levels, and blood pressure in healthy menAm J Cardiol · PMID 10235107 Acute effects of melatonin administration on cardiovascular autonomic regulation in healthy menAm Heart J · PMID 11320384 Influences of melatonin administration on the circulation of womenAm J Physiol · PMID 9486289 Effects of Melatonin Supplementation On Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.Horm Metab Res · PMID 30861561
	Cerebral Blood Flow	Improves (the measure goes up)		1 study	10 people
Studies that measured cerebral blood flow Melatonin differentially affects vascular blood flow in humansAm J Physiol Heart Circ Physiol · PMID 21148765
	Blood glucose	Improves (the measure goes down)			30 people
	C-Reactive Protein (CRP)	Improves (the measure goes down)			30 people
	Fibrinogen	Improves (the measure goes up)			30 people
	Heart Rate	Improves (the measure goes down)			17 people
	High-density lipoprotein (HDL)	Improves (the measure goes up)			30 people
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			30 people
	Noradrenaline	Improves (the measure goes up)			17 people
	Oxidative Stress Biomarkers	Improves (the measure goes down)			30 people
	Total cholesterol	Improves (the measure goes down)			30 people
	Triglycerides	Improves (the measure goes down)			30 people

High Cholesterol

Anti-Oxidant Enzyme Profile: improves
Blood Pressure: improves
Blood glucose: improves

High Cholesterol: outcomes studied for Melatonin
Grade	Outcome	Effect	Size	Studies	People
	Anti-Oxidant Enzyme Profile Small Increase	Improves (the measure goes up)	Small effect	1 study	30 people
Studies that measured anti-oxidant enzyme profile Melatonin treatment improves blood pressure, lipid profile, and parameters of oxidative stress in patients with metabolic syndromeJ Pineal Res · PMID 21138476
	Blood Pressure	Improves (the measure goes down)		5 studies	30 people
Studies that measured blood pressure Effect of melatonin supplementation on body composition and blood pressure in adults: A systematic review and Dose-Response meta-analysis of randomized controlled trial.Heliyon · PMID 39113944 Effects of melatonin on vascular reactivity, catecholamine levels, and blood pressure in healthy menAm J Cardiol · PMID 10235107 Acute effects of melatonin administration on cardiovascular autonomic regulation in healthy menAm Heart J · PMID 11320384 Influences of melatonin administration on the circulation of womenAm J Physiol · PMID 9486289 Effects of Melatonin Supplementation On Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.Horm Metab Res · PMID 30861561
	Blood glucose	Improves (the measure goes down)			30 people
	C-Reactive Protein (CRP)	Improves (the measure goes down)			30 people
	Fibrinogen	Improves (the measure goes up)			30 people
	High-density lipoprotein (HDL)	Improves (the measure goes up)			30 people
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			30 people
	Oxidative Stress Biomarkers	Improves (the measure goes down)			30 people
	Total cholesterol	Improves (the measure goes down)			30 people
	Triglycerides	Improves (the measure goes down)			30 people

Metabolic Syndrome

Anti-Oxidant Enzyme Profile: improves
Blood Pressure: improves
Blood glucose: improves

Metabolic Syndrome: outcomes studied for Melatonin
Grade	Outcome	Effect	Size	Studies	People
	Anti-Oxidant Enzyme Profile Small Increase	Improves (the measure goes up)	Small effect	1 study	30 people
Studies that measured anti-oxidant enzyme profile Melatonin treatment improves blood pressure, lipid profile, and parameters of oxidative stress in patients with metabolic syndromeJ Pineal Res · PMID 21138476
	Blood Pressure	Improves (the measure goes down)		5 studies	30 people
Studies that measured blood pressure Effect of melatonin supplementation on body composition and blood pressure in adults: A systematic review and Dose-Response meta-analysis of randomized controlled trial.Heliyon · PMID 39113944 Effects of melatonin on vascular reactivity, catecholamine levels, and blood pressure in healthy menAm J Cardiol · PMID 10235107 Acute effects of melatonin administration on cardiovascular autonomic regulation in healthy menAm Heart J · PMID 11320384 Influences of melatonin administration on the circulation of womenAm J Physiol · PMID 9486289 Effects of Melatonin Supplementation On Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.Horm Metab Res · PMID 30861561
	Blood glucose	Improves (the measure goes down)			30 people
	C-Reactive Protein (CRP)	Improves (the measure goes down)			30 people
	Fibrinogen	Improves (the measure goes up)			30 people
	High-density lipoprotein (HDL)	Improves (the measure goes up)			30 people
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			30 people
	Oxidative Stress Biomarkers	Improves (the measure goes down)			30 people
	Total cholesterol	Improves (the measure goes down)			30 people
	Triglycerides	Improves (the measure goes down)			30 people

Soccer Performance

Anti-Oxidant Enzyme Profile: improves
Exercise-Induced Oxidation: changes; see studies

Soccer Performance: outcomes studied for Melatonin
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Anti-Oxidant Enzyme Profile Small Increase	Improves (the measure goes up)	Small effect	1 study	16 people
	Exercise-Induced Oxidation	Changes; see studies		2 studies	16 people

Endometriosis

Dyschezia: improves
Dysmenorrhea Symptoms: improves
Serum BDNF: improves

Endometriosis: outcomes studied for Melatonin
Outcome	Effect	Size	Studies	People
Dyschezia Moderate Improvement	Improves (the measure goes up)	Moderate effect		40 people
Dysmenorrhea Symptoms	Improves (the measure goes down)		1 study	40 people
Serum BDNF	Improves (the measure goes up)		1 study	40 people
Dyspareunia	Improves (the measure goes up)			40 people
Dysuria	Improves (the measure goes up)			40 people
Endometriosis-associated pelvic pain	Improves (the measure goes down)			40 people
Sleep Quality	Improves (the measure goes up)			40 people

Gastroesophageal Reflux Disease (GERD)

Gastrin: changes; see studies
Lower Esophageal Pressure: improves
GERD Symptoms: improves

Gastroesophageal Reflux Disease (GERD): outcomes studied for Melatonin
Outcome	Effect	Size	Studies	People
Gastrin Moderate Increase	Changes; see studies	Moderate effect		60 people
Lower Esophageal Pressure	Improves (the measure goes up)		1 study	60 people
GERD Symptoms	Improves (the measure goes down)			60 people
Heartburn Symptoms	Improves (the measure goes down)			60 people

General Gut Health

Gastrin: changes; see studies
Plasma Melatonin: improves
Stomach Ulcers: improves

General Gut Health: outcomes studied for Melatonin
Outcome	Effect	Size	Studies	People
Gastrin Moderate Increase	Changes; see studies	Moderate effect		30 people
Plasma Melatonin	Improves (the measure goes up)		1 study	30 people
Stomach Ulcers	Improves (the measure goes up)			30 people

H. Pylori Infection

Gastrin: changes; see studies
Ghrelin: improves
Leptin: improves

H. Pylori Infection: outcomes studied for Melatonin
Outcome	Effect	Size	Studies	People
Gastrin Moderate Increase	Changes; see studies	Moderate effect		21 people
Ghrelin	Improves (the measure goes up)		1 study	21 people
Leptin	Improves (the measure goes up)		1 study	21 people
Stomach Ulcers	Improves (the measure goes up)			21 people

Nonalcoholic Steatohepatitis (NASH)

Adiponectin: improves
Ghrelin: improves
Leptin: improves

Nonalcoholic Steatohepatitis (NASH): outcomes studied for Melatonin
Outcome	Effect	Size	Studies	People
Adiponectin Small Increase	Improves (the measure goes up)	Small effect		16 people
Ghrelin	Improves (the measure goes up)		1 study	16 people
Leptin	Improves (the measure goes up)		1 study	16 people
Glycemic Control	Improves (the measure goes up)			16 people
Insulin	Changes; see studies			16 people
Liver Enzymes	Changes; see studies			16 people
Resistin	Improves (the measure goes up)			16 people

H. Pylori Infection

Gastrin: improves
Ghrelin: improves
Leptin: improves

H. Pylori Infection: outcomes studied for Melatonin
Outcome	Effect	Size	Studies	People
Gastrin Moderate Increase	Improves (the measure goes up)	Moderate effect		21 people
Ghrelin	Improves (the measure goes up)		1 study	21 people
Leptin	Improves (the measure goes up)		1 study	21 people
Stomach Ulcers	Improves (the measure goes up)			21 people

Multiple Sclerosis (MS)

Heart Rate Variability
Walking Ability: improves
Sleep Quality: improves

Multiple Sclerosis (MS): outcomes studied for Melatonin
Outcome	Effect	Size	Studies	People
Heart Rate Variability No effect		NoneNo effect	1 study	27 people
Walking Ability	Improves (the measure goes up)		1 study	27 people
Sleep Quality	Improves (the measure goes up)			27 people

Breast Cancer

Breast Cancer Risk
IGF-1: improves
Estrogen: changes; see studies

Breast Cancer: outcomes studied for Melatonin
Outcome	Effect	Size	Studies	People
Breast Cancer Risk No effect		NoneNo effect	1 study	863 people
IGF-1	Improves (the measure goes up)		1 study	86 people
Estrogen	Changes; see studies			86 people

Metabolic Health

Adrenaline
Blood Pressure: improves
Exercise-Induced Oxidation: changes; see studies

Metabolic Health: outcomes studied for Melatonin
Outcome	Effect	Size	Studies	People
Adrenaline No effect		NoneNo effect		14 people
Blood Pressure	Improves (the measure goes down)		5 studies	14 people
Exercise-Induced Oxidation	Changes; see studies		2 studies	20 people
Growth Hormone	Improves (the measure goes up)		2 studies	18 people
Blood Flow	Improves (the measure goes up)			14 people
Cortisol	Improves (the measure goes down)			10 people
Heart Rate	Improves (the measure goes down)			14 people
Inflammation	Improves (the measure goes down)			20 people
Muscle Damage	Changes; see studies			20 people
Noradrenaline	Improves (the measure goes up)			14 people
Oxidative Stress Biomarkers	Improves (the measure goes down)			20 people
Prolactin	Improves (the measure goes up)			10 people

General Cardiovascular Health

Adrenaline
Blood Pressure: improves
Blood Flow: improves

General Cardiovascular Health: outcomes studied for Melatonin
Outcome	Effect	Size	Studies	People
Adrenaline No effect		NoneNo effect		40 people
Blood Pressure	Improves (the measure goes down)		5 studies	1,543 people
Blood Flow	Improves (the measure goes up)			14 people
Body Mass Index (BMI)	Improves (the measure goes down)			1,543 people
Dopamine	Improves (the measure goes up)			26 people
Heart Rate	Improves (the measure goes down)			14 people
Hip Circumference	Improves (the measure goes down)			1,543 people
Noradrenaline	Improves (the measure goes up)			40 people
Waist circumference	Improves (the measure goes down)			1,543 people
Weight	Improves (the measure goes down)			1,543 people

Type 2 Diabetes

Blood glucose
HbA1c: improves

Type 2 Diabetes: outcomes studied for Melatonin
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Blood glucose No effect		NoneNo effect		291 people
	HbA1c	Improves (the measure goes down)		1 study	325 people

Memory Improvement

Adrenaline
Anxiety Symptoms: improves
Alertness: improves

Memory Improvement: outcomes studied for Melatonin
Outcome	Effect	Size	Studies	People
Adrenaline No effect		NoneNo effect		50 people
Anxiety Symptoms	Improves (the measure goes down)		1 study	50 people
Alertness	Improves (the measure goes up)			50 people
Attention	Improves (the measure goes up)			50 people
Cortisol	Improves (the measure goes down)			50 people
Memory	Improves (the measure goes up)			50 people
Noradrenaline	Improves (the measure goes up)			50 people

Stress

Adrenaline
Anxiety Symptoms: improves
Alertness: improves

Stress: outcomes studied for Melatonin
Outcome	Effect	Size	Studies	People
Adrenaline No effect		NoneNo effect		50 people
Anxiety Symptoms	Improves (the measure goes down)		1 study	50 people
Alertness	Improves (the measure goes up)			50 people
Attention	Improves (the measure goes up)			50 people
Cortisol	Improves (the measure goes down)			50 people
Memory	Improves (the measure goes up)			50 people
Noradrenaline	Improves (the measure goes up)			50 people

Chronic Kidney Disease (CKD)

Cerebral Blood Flow: improves

Chronic Kidney Disease (CKD): outcomes studied for Melatonin
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Cerebral Blood Flow	Improves (the measure goes up)		1 study	10 people

General Cancer Care and Prevention

Cancer Mortality: improves

General Cancer Care and Prevention: outcomes studied for Melatonin
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Cancer Mortality	Improves (the measure goes down)		1 study	643 people

Eye Health

Intraocular Pressure: improves

Eye Health: outcomes studied for Melatonin
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Intraocular Pressure	Improves (the measure goes up)		1 study	9 people

Jet Lag

Jet Lag Symptoms: improves

Jet Lag: outcomes studied for Melatonin
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Jet Lag Symptoms	Improves (the measure goes down)		1 study	142 people

What the published studies found

5 automated readings

Automated reading of the published studies (Decosa evidence engine), for outcomes Dr. Grey has not graded yet. It is not a Dr. Grey grade and does not change one. How it is read

LDL cholesterol
The studies disagree. The best available review (2026, 10 studies) found little or no difference in LDL cholesterol, while 3 of the 8 studies read found an improvement. The evidence is very weak.
Side effects: 1 of the 1 study that reported on them found more with Melatonin.
8 studies counted of 9 read: 4 reviews and 2 trials (79 people in the trials).
1. Systematic review, 2026; 10 studies; patients with chronic kidney disease: no clear difference (the review the verdict rests on). Also, MLT supplementation had no significant effect on triglycerides, total cholesterol, low-density lipoprotein cholesterol, or … The effect of melatonin supplementation on lipid profile, oxidative stress, inflammatory marker, and sleep quality in patients with chronic kidney disease: a GRADE assessed meta-analysisPubMed 41727206
2. Meta-analysis, 2025; 63 studies: improves. Comprehensive Effects of Melatonin Supplementation on Cardiometabolic Risk Factors: A Systematic Review and Dose-Response Meta-AnalysisPubMed 41515249
3. Meta-analysis, 2019; 12 studies, 641 people: no clear difference. melatonin may improve low density lipoprotein cholesterol The effect of melatonin supplementation on lipid profile and anthropometric indices: A systematic review and meta-analysis of clinical trialsPubMed 31235113
4. Meta-analysis, 2018; 8 studies: no clear difference. Effects of melatonin supplementation on blood lipid concentrations: A systematic review and meta-analysis of randomized controlled trialsPubMed 29191493
5. Non-randomised trial, 2025; 154 people; type 2 diabetes patients with cognitive impairment: no clear difference. No significant effects were observed on LDL-c Melatonin Supplementation Improves Cognitive Function in Type-2 Diabetes Mellitus: A Quasi-Experimental StudyPubMed 41281014
6. Randomised trial, 2019; 58 people; women with polycystic ovary syndrome: improves. Effects of melatonin administration on mental health parameters, metabolic and genetic profiles in women with polycystic ovary syndrome: A randomized, double-blind, placebo-controlled trialPubMed 30831541
7. Non-randomised trial, 2011; 30 people; patients with metabolic syndrome: improves. Melatonin treatment improves blood pressure, lipid profile, and parameters of oxidative stress in patients with metabolic syndromePubMed 21138476
8. Crossover trial, 1997; 21 people; patients with hypercholesterolemia: no clear difference. no statistically significant difference in lipid components Effect of melatonin on serum lipids in patients with hypercholesterolemia: a pilot studyPubMed 10423639
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Jet lag
The studies disagree. A Cochrane review (2002, 10 studies) found an improvement in jet lag, while 1 of the 10 studies read found no clear difference. The evidence is very weak.
10 studies counted of 10 read: 7 reviews and 3 trials (77 people in the trials).
1. Systematic review, 2002; 10 studies; airline passengers, staff, or military personnel crossing time zones: improves (the review the verdict rests on). decreased jet-lag from flights crossing five or more time zones Melatonin for the prevention and treatment of jet lagPubMed 12076414
2. Meta-analysis, 2021; 23 studies; healthy adults: improves. melatonin reduced self-reported jetlag following eastbound Efficacy of Functional Foods, Beverages, and Supplements Claiming to Alleviate Air Travel Symptoms: Systematic Review and Meta-AnalysisPubMed 33809656
3. Meta-analysis, 2015; 11 studies; travelers crossing multiple time zones: improves. melatonin probably reduces symptoms associated with jet lag Is melatonin useful for jet lag?PubMed 26731279
4. Meta-analysis, 2006; 17 studies, 651 people; people with secondary sleep disorders and sleep restriction: no clear difference. no evidence that melatonin had an effect on sleep onset latency Efficacy and safety of exogenous melatonin for secondary sleep disorders and sleep disorders accompanying sleep restriction: meta-analysisPubMed 16473858
5. Systematic review, 2001; 10 studies; airline passengers, staff, military crossing time zones: improves. decreased jet-lag from flights crossing five or more time zones Melatonin for preventing and treating jet lagPubMed 11279722
6. Systematic review, 1997; patients with circadian rhythm sleep disorders: improves. [Melatonin--a natural hypnotic?]PubMed 9441514
7. Systematic review, 1996; time zone travellers and night shift workers: improves. Use of melatonin in circadian rhythm disorders and following phase shiftsPubMed 8787196
8. Randomised trial, 2001; 27 people; US Air Force reservists: improves. allows a faster resynchronization of hormone rhythms Resynchronization of hormonal rhythms after an eastbound flight in humans: effects of slow-release caffeine and melatoninPubMed 11513308
9. Randomised trial, 1992; 30 people: improves. self-ratings significantly discriminated between melatonin and placebo Melatonin and jet lag: confirmatory result using a simplified protocolPubMed 1457626
10. Crossover trial, 1989; 20 people; twenty volunteers with transcontinental flight experience: improves. Feelings of jet lag were less for subjects taking melatonin Effect of melatonin on jet lag after long haul flightsPubMed 2496815
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Memory
The studies read do not show a clear benefit for memory. One reading found mixed results, a second reading of the same search found little or no difference. The evidence is very weak.
Possible harm: 2 studies read reported a worse result for memory with Melatonin. One abstract says: "Memory scanning speed and perception of mental load were adversely affected." Check the studies below, and ask a doctor or pharmacist if this applies to you.
8 studies counted of 11 read: 3 reviews and 5 trials (129 people in the trials).
1. Systematic review, 2026: improves (the review the verdict rests on). Nutritional supplements and cognition in healthy aging and mild cognitive impairment patients: a systematic review and network meta-analysisPubMed 41764841
2. Systematic review, 2025; 26 studies, 23,839 people; patients with cognitive dysfunction induced by multiple sclerosis: worsens. Pharmacological treatment options for cognitive dysfunction induced by multiple sclerosis: a network meta-analysisPubMed 41127289
3. Meta-analysis, 2021; 22 studies: no clear difference. melatonin did not reduce memory function Neurocognitive effects of melatonin treatment in healthy adults and individuals with Alzheimer's disease and insomnia: A systematic review and meta-analysis of randomized controlled trialsPubMed 33957167
4. Randomised trial, 2020; 36 people; women undergoing adjuvant chemotherapy for breast cancer: improves. enhanced episodic memory (immediate and delayed) and recognition on RAVLT Clinical impact of melatonin on breast cancer patients undergoing chemotherapy; effects on cognition, sleep and depressive symptoms: A randomized, double-blind, placebo-controlled trialPubMed 32302347
5. Randomised trial, 2007; 13 people; non-sleep deprived volunteers: no clear difference. Cognitive performance following premature awakening from zolpidem or melatonin induced daytime sleepPubMed 17225476
6. Crossover trial, 2007; healthy adults undergoing fMRI memory tasks: improves. Exogenous melatonin further reduced activation in this region Melatonin and the human hippocampus, a time dependent interplayPubMed 17614839
7. Crossover trial, 2005; 80 people; 80 healthy adults: no clear difference. no memory or performance impairment (P > .05) Daytime sleep and performance following a zolpidem and melatonin cocktailPubMed 15700725
8. Randomised trial, 1993; police officers working seven successive night shifts: worsens. Memory scanning speed and perception of mental load were adversely affected Can melatonin improve shift workers' tolerance of the night shift? Some preliminary findingsPubMed 8261530
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Sleep quality
The studies disagree. A Cochrane review (2018, 4 studies, 151 people) did not settle it for sleep quality, while 3 of the 8 studies read found an improvement. The evidence is very weak.
Side effects: 1 of the 7 studies that reported on them found more with Melatonin (headaches, gastrointestinal problems, dizziness).
8 studies counted of 11 read: 7 reviews and 1 trial (57 people in the trials).
1. Systematic review, 2018; 4 studies, 151 people; adults in the intensive care unit: unclear: evidence too weak to tell (the review the verdict rests on). Melatonin for the promotion of sleep in adults in the intensive care unitPubMed 29746721
2. Systematic review, 2026; 98 studies, 28,920 people; individuals with chronic non-cancer pain: improves. melatonin significantly improved sleep quality compared with placebo Comparative effectiveness and safety of pharmacological interventions for sleep outcomes in chronic non-cancer pain: a systematic review and network meta-analysisPubMed 42430948
3. Meta-analysis, 2026; 23 studies, 2,028 people; people with chronic or postoperative musculoskeletal pain: mixed results. Sleep quality favoured melatonin in people with chronic MSK pain Efficacy and effectiveness of melatonin for the management of musculoskeletal pain: a systematic review and meta-analysis of placebo and active controlled trialsPubMed 42378431
4. Systematic review, 2026; 23 studies, 1,941 people; adults with migraine and sleep disturbances: no clear difference. Interventions for Migraine and Sleep: A Systematic Review Exploring Their Bidirectional AssociationPubMed 41874004
5. Systematic review, 2026; 7 studies, 497 people; menopausal women: no clear difference. A systematic review and meta-analysis of randomized controlled trials investigated the effects of melatonin supplementation on bone mineral density, quality of life, and sleep in menopausal womenPubMed 41693954
6. Meta-analysis, 2026; 4 studies, 455 people; patients undergoing total joint arthroplasty: no clear difference. melatonin did not significantly impact subjective or objective sleep outcomes Evaluating Whether Melatonin Impacts Postoperative Sleep Following Total Joint Arthroplasty: A Systematic Review and Meta-analysis of Randomized Controlled TrialsPubMed 42205627
7. Meta-analysis, 2026; 7 studies, 409 people: improves. The Effectiveness of Melatonin for Sleep Disturbances in Parkinson' Disease: Systematic Review and Meta-AnalysisPubMed 40588412
8. Randomised trial, 2026; 57 people; patients undergoing urological surgery: improves. sleep-quality scores increased significantly in the melatonin group The effect of preoperative melatonin patches on sleep quality in patients undergoing urological surgeryPubMed 42138936
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Stress
The best available review (2026, 10 studies) found an improvement in stress. That review studied patients with chronic kidney disease. 4 of the 5 studies read agree; 1 found mixed results. The evidence is moderate.
5 studies counted of 10 read: 4 reviews and 1 trial (49 people in the trials).
1. Systematic review, 2026; 10 studies; patients with chronic kidney disease: improves (the review the verdict rests on). The effect of melatonin supplementation on lipid profile, oxidative stress, inflammatory marker, and sleep quality in patients with chronic kidney disease: a GRADE assessed meta-analysisPubMed 41727206
2. Systematic review, 2024; 10 studies, 485 people: improves. Melatonin increased superoxide dismutase in nine studies, glutathione peroxidase in seven studies, and catalase in … Antioxidant Actions of Melatonin: A Systematic Review of Animal StudiesPubMed 38671887
3. Meta-analysis, 2020; 12 studies: mixed results. significant increase in total antioxidant capacity (TAC) Effect of melatonin supplementation on oxidative stress parameters: A systematic review and meta-analysisPubMed 33007423
4. Meta-analysis, 2020; 15 studies: improves. Effects of melatonin supplementation on oxidative stress: a systematic review and meta-analysis of randomized controlled trialsPubMed 33185572
5. Randomised trial, 2026; 49 people: improves. decrease in malondialdehyde, advanced oxidation protein products Benefits of 12-week self-paced training combined with melatonin supplementation on oxidative stress, inflammation, hyperlipidemia, and body composition in multiple sclerosis patients: A randomized controlled trialPubMed 42217742
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.

Key findings

Insomnia Signs and SymptomsInsomniaImproves (the measure goes down)
Abdominal PainIrritable Bowel Syndrome (IBS)Improves (the measure goes down)
Blood PressureBody CompositionImproves (the measure goes down)

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Studies cited

38 studies from PubMed

Plasma insulin, leptin, adiponectin, resistin, ghrelin, and melatonin in nonalcoholic steatohepatitis patients treated with melatoninJ Pineal Res · PMID 22804755
Effect of melatonin supplementation on body composition and blood pressure in adults: A systematic review and Dose-Response meta-analysis of randomized controlled trial.Heliyon · PMID 39113944
Effects of melatonin on vascular reactivity, catecholamine levels, and blood pressure in healthy menAm J Cardiol · PMID 10235107
Acute effects of melatonin administration on cardiovascular autonomic regulation in healthy menAm Heart J · PMID 11320384
Melatonin administration and pituitary hormone secretionClin Endocrinol · PMID 9509065
The effect of melatonin administration on pituitary hormone secretion in manClin Endocrinol · PMID 10594526
Melatonin supplementation ameliorates oxidative stress and inflammatory signaling induced by strenuous exercise in adult human malesJ Pineal Res · PMID 21615492
The potential therapeutic effect of melatonin in Gastro-Esophageal Reflux DiseaseBMC Gastroenterol · PMID 20082715
The effect of prolonged-release melatonin on sleep measures and psychomotor performance in elderly patients with insomniaInt Clin Psychopharmacol · PMID 19584739
Evaluation of sleep, puberty and mental health in children with long-term melatonin treatment for chronic idiopathic childhood sleep onset insomniaPsychopharmacology · PMID 21340475
Prolonged-release melatonin improves sleep quality and morning alertness in insomnia patients aged 55 years and older and has no withdrawal effectsJ Sleep Res · PMID 18036082
Effect of melatonin on insomnia and daytime sleepiness, in patients with obstructive sleep apnea and insomnia (COMISA): A randomized double-blinded placebo-controlled trial.J Pharm Health Care Sci · PMID 38816846
Effects of melatonin and tryptophan on healing of gastric and duodenal ulcers with Helicobacter pylori infection in humansJ Physiol Pharmacol · PMID 22204799
Melatonin differentially affects vascular blood flow in humansAm J Physiol Heart Circ Physiol · PMID 21148765
Melatonin treatment improves blood pressure, lipid profile, and parameters of oxidative stress in patients with metabolic syndromeJ Pineal Res · PMID 21138476
Influences of melatonin administration on the circulation of womenAm J Physiol · PMID 9486289
Effects of Melatonin Supplementation On Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.Horm Metab Res · PMID 30861561
Treatment of central and sensorineural tinnitus with orally administered Melatonin and Sulodexide: personal experience from a randomized controlled studyActa Otorhinolaryngol Ital · PMID 20111618
Melatonin: can it stop the ringing?Ann Otol Rhinol Laryngol · PMID 21859051
The effects of melatonin on tinnitus and sleepOtolaryngol Head Neck Surg · PMID 16455366
Effect of melatonin on tinnitusLaryngoscope · PMID 9504599
Prophylaxis of migraine with melatonin: a randomized controlled trialNeurology · PMID 20975054
Randomised clinical trial comparing melatonin 3 mg, amitriptyline 25 mg and placebo for migraine prevention.J Neurol Neurosurg Psychiatry · PMID 27165014
Efficacy on sleep parameters and tolerability of melatonin in individuals with sleep or mental disorders: A systematic review and meta-analysis.Neurosci Biobehav Rev · PMID 35691474
Melatonin improves memory acquisition under stress independent of stress hormone releasePsychopharmacology · PMID 18853147
Efficacy of melatonin in the treatment of endometriosis: a phase II, randomized, double-blind, placebo-controlled trialPain · PMID 23602498
A randomized controlled trial of oral melatonin supplementation and breast cancer biomarkersCancer Causes Control · PMID 22370698
Urinary 6-Sulphatoxymelatonin levels and risk of breast cancer in premenopausal women: the ORDET cohortCancer Epidemiol Biomarkers Prev · PMID 20200429
Melatonin administrated immediately before an intense exercise reverses oxidative stress, improves immunological defenses and lipid metabolism in football playersPhysiol Behav · PMID 22212240
Melatonin for the prevention and treatment of jet lagCochrane Database Syst Rev · PMID 12076414
Role of melatonin in mucosal gastroprotection against aspirin-induced gastric lesions in humansJ Pineal Res · PMID 20443220
Effect of melatonin on intraocular pressureCurr Eye Res · PMID 3416618
Melatonin in the treatment of cancer: a systematic review of randomized controlled trials and meta-analysisJ Pineal Res · PMID 16207291
The efficacy of exogenous melatonin supplement in ameliorating irritable bowel syndrome severity: A meta-analysis of randomized controlled trials.J Formos Med Assoc · PMID 36257872
Effects of melatonin supplementation on BDNF concentrations and depression: A systematic review and meta-analysis of randomized controlled trials.Behav Brain Res · PMID 36049659
12-week melatonin supplementation improved dynamic postural stability and walking performance in persons living with multiple sclerosis: A randomized controlled trial.Behav Brain Res · PMID 39122092
12-week melatonin intake attenuates cardiac autonomic dysfunction and oxidative stress in multiple sclerosis patients: a randomized controlled trial.Metab Brain Dis · PMID 39630381
The effect of melatonin supplementation on glycemic control in patients with type 2 diabetes.Front Endocrinol · PMID 40698248

Evidence by condition

H. Pylori Infection

General Cardiovascular Health

What the published studies found

LDL cholesterol

Jet lag

Memory

Sleep quality

Stress

Key findings

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Studies cited

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Protocols that include Melatonin