How can melatonin help you? What the research says

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Clinical reviewer

Dugald Seely, ND, MSc

Physician, researcher, and CancerChoices advisor

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Last update: July 22, 2026

We summarize the clinical evidence for each medical benefit here. We begin with our assessment of the strength of evidence within each category, followed by a brief summary of individual studies or reviews of several studies. In assessing the strength of evidence, we consider the study design, number of participants, and the size of the treatment effect (how much outcomes changed with treatment).

To see more details, click the plus sign to the right of any section.

Our assessments of evidence for each medical benefit fall into one of these categories:

Strong evidence: consistent, significant effects in several large (or at least one very large) well designed clinical studies or at least two meta-analysesa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of clinical studies of moderate or better quality (or one large meta-analysis) finding similar results
Good evidence: significant effects in one large or several mid-sized and well-designed clinical studies ( randomized controlled trialsa study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects with an appropriate placebo or other strong comparison control or observational studies that control for confounds)
Modest evidence: significant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies), or several small studies aggregated into a meta-analysis
Preliminary evidence: significant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect
Weak evidence: one or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects
Insufficient evidence: preclinical evidence only OR clinical studies with such poor or unclear methodology that no conclusion can be drawn OR conflicting findings across clinical studies with no preponderance of evidence in one direction; conflicting evidence occurs when studies find conflicting effects (positive effect vs no effect or negative effect) with the same treatment and the same general study population (same cancer type, for example)

Learn more about how we research and rate therapies and practices in How We Rate Therapies ›

Improving treatment outcomes

Is melatonin linked to improved survival? Is it linked to less cancer growth or metastasis? Does it enhance the anticancer action of other treatments or therapies? We present the evidence.

Cancer as a whole

Strong evidenceconsistent, significant effects in several large (or at least one very large) well designed clinical studies or at least two meta-analyses of clinical studies of moderate or better quality (or one large meta-analysis) finding similar results (this is the CancerChoices definition; other researchers and studies may define this differently): Across many cancer types, people with solid tumors who were treated with melatonin alongside conventional cancer treatment showed longer survival and improved responses to treatment in many combined analyses of studies.

37% lower mortalitydeath, or the death rate in a population; cancer studies often report all-cause mortality (death from any cause) and cancer-specific mortality (death due to the cancer under investigation) at 1 year with substantially improved rates for complete response, partial response, and stable disease among people with solid tumors receiving chemotherapy, radiotherapy, supportive care, or palliative care treated with melatonin compared to controls in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 21 randomized trials¹Seely D, Wu P et al. Melatonin as adjuvant cancer care with and without chemotherapy: a systematic review and meta-analysis of randomized trials. Integrative Cancer Therapies. 2012;11(4):293-303.
Almost double the rates of complete and partial remission and of survival among people with solid tumor cancers receiving chemotherapy or radiotherapy and treated with 20 mg oral melatonin compared to controls in a meta-analysis of 8 RCTsrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects²Wang YM, Jin BZ, Ai F, Duan CH, Lu YZ, Dong TF, Fu QL. The efficacy and safety of melatonin in concurrent chemotherapy or radiotherapy for solid tumors: a meta-analysis of randomized controlled trials. Cancer Chemotherapy and Pharmacology. 2012 May;69(5):1213-20.
34% lower mortality at 1 year among people with solid tumors treated with melatonin either as sole treatment or as adjuncta therapy connected or added to a main treatment or therapy, not used alone to other treatments compared to controls in a meta-analysis of 10 RCTs³Mills E, Wu P, Seely D, Guyatt G. Melatonin in the treatment of cancer: a systematic review of randomized controlled trials and meta-analysis. Journal of Pineal Research. 2005 Nov;39(4):360-6.
Substantially higher tumor remission rates and more than double the overall survival rate among people with non-small-cell lung cancer and various solid tumors treated with melatonin and chemotherapy or other treatments compared to the other treatments alone in a meta-analysis of 20 clinical trials⁴Wang Y, Wang P, Zheng X, Du X. Therapeutic strategies of melatonin in cancer patients: a systematic review and meta-analysis. OncoTargets and Therapy. 2018 Nov 8;11:7895-7908.

Advanced cancer

Weak evidenceone or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects (this is the CancerChoices definition; other researchers and studies may define this differently): People with advanced cancer who had naturally high melatonin levels were more likely to respond to treatment in one observational study. This study did not look at whether taking a melatonin supplement increased response to treatment.

Brain cancer

No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. in people with brain metastases: People with brain metastases from other cancers taking high doses of melatonin (20mg) did not show evidence of an effect in one trial.

Lung cancer

Insufficient (mixed) evidencepreclinical evidence only OR clinical studies with such poor or unclear methodology that no conclusion can be drawn OR conflicting findings across clinical studies with no preponderance of evidence in one direction; conflicting evidence occurs when studies find conflicting effects (positive effect vs no effect or negative effect) with the same treatment and the same general study population (same cancer type, for example) (this is the CancerChoices definition; other researchers and studies may define this differently): People with advanced lung cancer taking melatonin in the evening have shown longer survival in two studies, but another study did not find an effect.

Melanoma

No evidence of an effect: People with melanoma treated with a small dose of melatonin alongside dacarbazine did not show evidence of better outcomes in one small study.

Optimizing your body terrain

Does melatonin promote an environment within your body that is less supportive of cancer development, growth, or spread? We present the evidence.

See Optimizing Your Body Terrain ›

Find medical professionals who specialize in managing body terrain factors: Finding Integrative Oncologists and Other Practitioners ›

Bleeding and coagulation imbalance

Preliminary evidencesignificant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect (this is the CancerChoices definition; other researchers and studies may define this differently) of lower levels of hemostatic measures promoting coagulation among healthy young men treated with melatonin

Body weight

Preliminary evidence: People with type 2 diabetes and no cancer who took melatonin supplements showed reductions in body weight in a small trial.

Hormone imbalance

No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. in breast cancer survivors: survivors of breast cancer treated with melatonin did not show evidence of an effect on estradiol or insulin-like growth factor, two hormones that can increase cancer growth under certain conditions, in a small trial.

Inflammation

Good evidencesignificant effects in one large or several mid-sized and well-designed clinical studies (randomized controlled trials (RCTs) with an appropriate placebo or other strong comparison control or observational studies that control for confounds) (this is the CancerChoices definition; other researchers and studies may define this differently): People treated with melatonin showed less inflammation in a large combined analysis of studies, not specific to cancer.

Oxidation

Good evidence: People treated with melatonin showed a greater antioxidant capacity in two combined analyses of studies and less oxidative DNA damage of less oxidation in one study, though none were specific to cancer. People with head and neck cancer treated with 20mg melatonin daily during radiation therapy retained more antioxidant capacity in one trial.

Other terrain factors

Preliminary evidence: People with type 2 diabetes and without cancer who were treated with melatonin supplements showed lower blood pressure in one study.

Melatonin combined with other complementary therapies

Managing side effects and promoting wellness

Is melatonin linked to fewer or less severe side effects or symptoms? Is it linked to less toxicity from cancer treatment? Does it support your quality of life or promote general well-being? We present the evidence.

Treatment side effects as a whole

Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently): People treated with melatonin tolerated chemotherapy better – meaning they had fewer or less severe side effects – across several studies. However, in a separate study on post-surgical outcomes, people treated with melatonin for a year after lung cancer resection did not show evidence of an effect on adverse events.

Anxiety

No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments.: People treated with melatonin for a year after lung cancer resection showed no evidence of an effect on anxiety in a large RCT.

Blood-related side effects

Modest evidence: People with cancer treated with melatonin during chemotherapy or radiotherapy had fewer dangerous drops in platelet counts (thrombocytopenia) across several studies, though one small trial did not find an effect.

Body composition or cachexia

Modest evidence: People with advanced cancer treated with melatonin showed less wasting (cachexia) across several studies, though one trial found that melatonin did not help people with cachexia regain weight.

Cardiovascular symptoms

Modest evidence: People with advanced cancer treated with melatonin during chemotherapy showed less heart damage (cardiotoxicity) in two studies. There was preliminary evidencesignificant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect (this is the CancerChoices definition; other researchers and studies may define this differently), from one study, that people receiving an experimental cancer treatment that could cause low blood pressure were more likely to maintain normal blood pressure when treated with large doses of nighttime melatonin.

Changes in appetite

No evidence of an effect: People with cancer cachexia treated with melatonin showed no evidence of better appetite in a small RCT.

Cognitive difficulties

Preliminary evidencesignificant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect (this is the CancerChoices definition; other researchers and studies may define this differently): People with breast cancer treated with melatonin during chemotherapy or hormone therapy showed better cognitive performance in two small studies.

Better performance related to executive function, episodic memory (immediate and delayed), recognition, and verbal fluency during a first cycle of adjuvant chemotherapy after lumpectomy or mastectomy among people with breast cancer treated with 20 mg oral melatonin daily approximately 1 hour before bedtime for 10 days beginning 3 days before their first chemotherapy session compared to placebo in a small RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects³⁹Palmer ACS, Zortea M et al. Clinical impact of melatonin on breast cancer patients undergoing chemotherapy; effects on cognition, sleep and depressive symptoms: A randomized, double-blind, placebo-controlled trial. PLoS One. 2020 Apr 17;15(4):e0231379.
Better cognitive function during hormonal or trastuzumab therapy among people with metastatic breast cancer treated with 5 mg melatonin at bedtime for 2 months compared to baseline in a small uncontrolled triala study in which a therapy is used, but without a comparison group against which to judge outcomes; an uncontrolled trial is considered a weak study design⁴⁰Innominato PF, Lim AS et al. The effect of melatonin on sleep and quality of life in patients with advanced breast cancer. Supportive Care in Cancer. 2016 Mar;24(3):1097-105.

Among adult survivors of childhood cancer

Preliminary evidence: Adults who had sleep impairments presumed to result from childhood cancer treatment and who were treated with melatonin showed better cognitive abilities in one study.

Adults who had survived childhood cancer treated with melatonin did not show sleep improvements as a whole; however, those who had either a sleep impairment or a cognitive impairment and who were treated with melatonin showed better cognitive abilities in a mid-sized RCT⁴¹Lubas MM, Mandrell BN et al. A randomized double-blind placebo-controlled trial of the effectiveness of melatonin on neurocognition and sleep in survivors of childhood cancer. Pediatric Blood and Cancer. 2022 Jan;69(1):e29393.

Depression

Modest evidence: People with breast cancer and without sleep disruption treated with melatonin showed at doses greater than 3mg showed reduced depression in a combined analysis of studies.

Fatigue

Insufficient (mixed) evidencepreclinical evidence only OR clinical studies with such poor or unclear methodology that no conclusion can be drawn OR conflicting findings across clinical studies with no preponderance of evidence in one direction; conflicting evidence occurs when studies find conflicting effects (positive effect vs no effect or negative effect) with the same treatment and the same general study population (same cancer type, for example) (this is the CancerChoices definition; other researchers and studies may define this differently): People treated with melatonin during cancer treatment showed less fatigue in some, but not all, studies. People with advanced cancer treated with melatonin showed less weakness in one study.

Hot flashes

No evidence: In a small trial, postmenopausal survivors of breast cancer treated with 3mg of melatonin daily did not show evidence of an effect on hot flashes.

Neurological side effects

Modest evidence: People treated with 20mg of melatonin daily showed less neurotoxicity (such as tingling or numbness) during radiation or chemotherapy in a combined analysis of studies.

Oral symptoms

Modest evidence: People with several types of cancer treated with melatonin showed less oral inflammation (oral mucositis or stomatitis) during radiation or chemotherapy in a combined analysis of studies, but those with head and neck cancer did not.

Pain

Insufficient (mixed) evidence: People with cancer and without sleep disruption who were treated with melatonin showed no evidence of an effect on pain in a combined analysis of studies, though people with prostate cancer treated with melatonin before prostatectomy showed lower pain scores following the procedure.

Quality of life and function

No evidence of an effect among people without a sleep disorder: A combined analysis of studies found that people with cancer and no sleep disruption who were treated with melatonin had no difference in quality of life.

Skin and tissue side effects

Preliminary evidence: People undergoing radiation after surgery for breast cancer treated with a melatonin emulsion (cream) showed less radiation dermatitis, a common side effect of radiotherapy, in a small trial.

Sleep disruption

Preliminary evidence: People with insomnia during cancer treatment who were treated with melatonin showed better sleep quality across several combined analyses of studies, though not as great an improvement as with cognitive behavioral therapy for insomnia (CBT-I). While less studied, there was weak evidenceone or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects (this is the CancerChoices definition; other researchers and studies may define this differently) from two small trials that people with insomnia during hormone therapy for breast or prostate cancer who were treated with melatonin had better sleep.

Symptoms not specific to cancer

Adults preparing for surgery or recovering from surgery (not specific to cancer) have shown less anxiety when treated with melatonin, comparable to results with benzodiazepines.

Anxiety before surgery

Good evidence: People treated with melatonin before surgery showed less anxiety both before and after surgery across several combined analyses of studies, with one analysis finding the effect was similar to benzodiazepines, a conventional psychiatric medication for anxiety.

Modest improvements in anxiety among adults preparing for surgery treated with melatonin compared to placebo in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 7 RCTsrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects of high quality, and comparable effects as midazolam in an analysis of 2 further RCTs⁶⁷Hansen MV, Halladin NL, Rosenberg J, Gögenur I, Møller AM. Melatonin for pre- and postoperative anxiety in adults. Cochrane Database of Systematic Reviews. 2015 Apr 9;2015(4):CD009861.
Modest improvements in anxiety before surgery among adults treated with melatonin compared to placebo in a meta-analysis of 18 RCTs of moderate quality⁶⁸Madsen BK, Zetner D, Møller AM, Rosenberg J. Melatonin for preoperative and postoperative anxiety in adults. Cochrane Database of Systematic Reviews. 2020 Dec 8;12(12):CD009861.
Comparable levels of anxiety before surgery among adults treated with melatonin or benzodiazepines in a meta-analysis of 7 RCTs of moderate quality⁶⁹Madsen BK, Zetner D, Møller AM, Rosenberg J. Melatonin for preoperative and postoperative anxiety in adults. Cochrane Database of Systematic Reviews. 2020 Dec 8;12(12):CD009861.
Slightly less anxiety immediately after surgery among adults treated with melatonin compared to placebo in a meta-analysis of 7 RCTs of low quality⁷⁰Madsen BK, Zetner D, Møller AM, Rosenberg J. Melatonin for preoperative and postoperative anxiety in adults. Cochrane Database of Systematic Reviews. 2020 Dec 8;12(12):CD009861.
Less delayed anxiety after surgery among adults treated with melatonin compared to placebo in a meta analysis of 2 RCTs of low quality⁷¹Madsen BK, Zetner D, Møller AM, Rosenberg J. Melatonin for preoperative and postoperative anxiety in adults. Cochrane Database of Systematic Reviews. 2020 Dec 8;12(12):CD009861.
Comparable levels of anxiety after surgery among adults treated with melatonin or benzodiazepines in a meta-analysis of 3 RCTs of low quality⁷²Madsen BK, Zetner D, Møller AM, Rosenberg J. Melatonin for preoperative and postoperative anxiety in adults. Cochrane Database of Systematic Reviews. 2020 Dec 8;12(12):CD009861.
Small improvements in anxiety 6 hours after surgery, but not at 90 minutes after surgery among adults treated with melatonin compared to placebo in a meta-analysis of 7 RCTs of moderate quality, and comparable to effects from treatment with midazolam in an analysis of 2 further RCTs⁷³Hansen MV, Halladin NL, Rosenberg J, Gögenur I, Møller AM. Melatonin for pre- and postoperative anxiety in adults. Cochrane Database of Systematic Reviews. 2015 Apr 9;2015(4):CD009861.
Lower anxiety scores among people preparing for surgery treated with melatonin compared to placebo in a systematic review of 24 controlled trialsa study design in which people are assigned to either an experimental group or a control group to compare the outcomes from different treatment; assignment is not random, and so this is not as strong a study design as a randomized controlled trial, but still stronger than an uncontrolled trial⁷⁴Andersen LP, Werner MU, Rosenberg J, Gögenur I. A systematic review of peri-operative melatonin. Anaesthesia. 2014 Oct;69(10):1163-71.

Depression

No evidence of an effect: People with depression (not specific to people with cancer) treated with melatonin showed no evidence of an improvement in a combined analysis of 4 trials.

No change in depression scores among people with depression treated with melatonin compared to placebo in a meta-analysis of 4 controlled trials⁷⁵Hansen MV, Danielsen AK, Hageman I, Rosenberg J, Gögenur I. The therapeutic or prophylactic effect of exogenous melatonin against depression and depressive symptoms: a systematic review and meta-analysis. European Neuropsychopharmacology. 2014 Nov;24(11):1719-28.

Pain after surgery

Modest evidence: people treated with melatonin before or shortly after surgery (not specific to cancer surgery) had less pain during recovery across several controlled trials.

Slightly less pain after surgery among people undergoing surgery treated with melatonin compared to placebo in a systematic review of controlled trials⁷⁶Andersen LP, Werner MU, Rosenberg J, Gögenur I. A systematic review of peri-operative melatonin. Anaesthesia. 2014 Oct;69(10):1163-71.
Lower pain severity, longer duration before needing analgesia after surgery, less need for analgesics after surgery, and quicker resumption of activity after elective cesarean section among people receiving 5 or 10 mg melatonin before surgery compared placebo in addition to spinal anesthesia, and greater benefit with the higher dose of melatonin for some effects, in a mid-sized RCT⁷⁷Kiabi FH, Emadi SA, Jamkhaneh AE, Aezzi G, Ahmadi NS. Effects of preoperative melatonin on postoperative pain following cesarean section: a randomized clinical trial. Annals of Medical Surgery (London). 2021 May 12;66:102345.
Lower mean pain scores and total morphine consumption, less supplemental analgesic, and less nausea and vomiting for 24 hours after surgery among adults treated with melatonin 1 hour before surgery compared to placebo in a mid-sized RCT⁷⁸Laflı Tunay D, Türkeün Ilgınel M et al. Comparison of the effects of preoperative melatonin or vitamin C administration on postoperative analgesia. Bosnian Journal of Basic Medical Sciences. 2020;20(1):117-124.

Melatonin combined with other therapies

Reducing cancer risk

Is this therapy linked to lower risks of developing cancer or of recurrence? We present the evidence.

Breast cancer

Preliminary evidencesignificant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect (this is the CancerChoices definition; other researchers and studies may define this differently): People with lower melatonin levels had a higher risk of breast cancer in several combined analyses of observational studies, but these did not test whether taking melatonin supplements would reduce cancer risk.

Lower levels of melatonin among women with breast cancer compared to controls without breast cancer in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 9 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods trials⁸⁰Veiga ECA, Simões R et al. Repercussions of melatonin on the risk of breast cancer: a systematic review and meta-analysis. Revista da Associação Médica Brasileira (1992). 2019 Jun 3;65(5):699-705.
Weak or very weak trendsan apparent change due to a therapy, close to but not achieving full statistical significance (this is the CancerChoices definition; other researchers and studies may define this differently toward higher risk of breast cancer among people with lower levels of a melatonin metabolite, but only among postmenopausal women, estrogen receptor positive breast cancer, or overnight urine samples; no evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on risk of breast cancer among women as a whole with the highest levels of the metabolite compared to other people in a meta-analysis of 6 observational studies⁸¹Xu J, Huang L, Sun GP. Urinary 6-sulfatoxymelatonin level and breast cancer risk: systematic review and meta-analysis. Scientific Reports. 2017 Jul 13;7(1):5353.
Modestly lower risk of breast cancer with higher urinary levels of melatonin in meta-analyses of 5⁸²Basler M, Jetter A et al. Urinary excretion of melatonin and association with breast cancer: meta-analysis and review of the literature. Breast Care (Basel). 2014 Jul;9(3):182-7. and 16⁸³Yang WS, Deng Q, Fan WY, Wang WY, Wang X. Light exposure at night, sleep duration, melatonin, and breast cancer: a dose-response analysis of observational studies. European Journal of Cancer Prevention. 2014 Jul;23(4):269-76. observational studies and a separate large observational study⁸⁴Wang XS, Tipper S et al. First-morning urinary melatonin and breast cancer risk in the Guernsey Study. American Journal of Epidemiology. 2014 Mar 1;179(5):584-93.

Lung cancer

Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently): People who were treated with 20mg melatonin nightly after surgery to resect stage 3 or 4 non-small-cell lung cancer had a lower risk of recurrence at 5 years in a large controlled trial.

Melanoma and other skin cancers

Preliminary evidence: people treated with 20mg melatonin nightly after surgery to remove melanoma showed a lower lower risk of melanoma recurrence in a small study.

Ovarian cancer

Weak evidenceone or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects (this is the CancerChoices definition; other researchers and studies may define this differently): Two observational studies found a correlation between lower melatonin levels and ovarian cancer, but did not investigate whether low melatonin could cause cancer.

Prostate cancer

Preliminary evidence: Lower melatonin levels were associated with a higher risk of prostate cancer in two observational studies, but these did not investigate whether low melatonin could cause cancer.

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References[+]

1	Seely D, Wu P et al. Melatonin as adjuvant cancer care with and without chemotherapy: a systematic review and meta-analysis of randomized trials. Integrative Cancer Therapies. 2012;11(4):293-303.
2	Wang YM, Jin BZ, Ai F, Duan CH, Lu YZ, Dong TF, Fu QL. The efficacy and safety of melatonin in concurrent chemotherapy or radiotherapy for solid tumors: a meta-analysis of randomized controlled trials. Cancer Chemotherapy and Pharmacology. 2012 May;69(5):1213-20.
3	Mills E, Wu P, Seely D, Guyatt G. Melatonin in the treatment of cancer: a systematic review of randomized controlled trials and meta-analysis. Journal of Pineal Research. 2005 Nov;39(4):360-6.
4	Wang Y, Wang P, Zheng X, Du X. Therapeutic strategies of melatonin in cancer patients: a systematic review and meta-analysis. OncoTargets and Therapy. 2018 Nov 8;11:7895-7908.
5	Lissoni P, Tancini G et al. Melatonin increase as predictor for tumor objective response to chemotherapy in advanced cancer patients. Tumori. 1988 Jun 30;74(3):339-45.
6	Berk L, Berkey B et al. Randomized phase II trial of high-dose melatonin and radiation therapy for RPA class 2 patients with brain metastases (RTOG 0119). International Journal of Radiation Oncology, Biology, Physics. 2007 Jul 1;68(3):852-7.
7	Seely D, Legacy M, et al. Adjuvant melatonin for the prevention of recurrence and mortality following lung cancer resection (AMPLCaRe): A randomized placebo controlled clinical trial. eClinicalMedicine, 2021; 33.
8	Hrushesky WJ, Lis CG et al. E. (2021). Daily evening melatonin prolongs survival among patients with advanced non-small-cell lung cancer. Biological Rhythm Research, 53(7), 1043–1057.
9, 18	Sookprasert A, Johns NP et al. Melatonin in patients with cancer receiving chemotherapy: a randomized, double-blind, placebo-controlled trial. Anticancer Research. 2014 Dec;34(12):7327-37.
10	Novik AV, Protsenko SA et al. Melatonin and metformin failed to modify the effect of dacarbazine in melanoma. Oncologist. 2021 May;26(5):364-e734.
11	Wirtz PH, Spillmann M, Bärtschi C, Ehlert U, von Känel R. Oral melatonin reduces blood coagulation activity: a placebo-controlled study in healthy young men. Journal of Pineal Research. 2008 Mar;44(2):127-33.
12, 20	Bazyar H, Zare Javid A, Bavi Behbahani H, Moradi F, Moradi Poode B, Amiri P. Consumption of melatonin supplement improves cardiovascular disease risk factors and anthropometric indices in type 2 diabetes mellitus patients: a double-blind, randomized, placebo-controlled trial. Trials. 2021 Mar 25;22(1):231.
13	Schernhammer ES, Giobbie-Hurder A et al. A randomized controlled trial of oral melatonin supplementation and breast cancer biomarkers. Cancer Causes Control. 2012 Apr;23(4):609-16.
14	Cho JH, Bhutani S, Kim CH, Irwin MR. Anti-inflammatory effects of melatonin: a systematic review and meta-analysis of clinical trials. Brain, Behavior, and Immunity. 2021 Mar;93:245-253.
15	Zarezadeh M, Khorshidi M et al. Melatonin supplementation and pro-inflammatory mediators: a systematic review and meta-analysis of clinical trials. European Journal of Nutrition. 2020 Aug;59(5):1803-1813.
16	Ghorbaninejad P, Sheikhhossein F et al. Effects of melatonin supplementation on oxidative stress: a systematic review and meta-analysis of randomized controlled trials. Hormone Molecular Biology and Clinical Investigation. 2020 Nov 13;41(4).
17	Morvaridzadeh M, Sadeghi E et al. Effect of melatonin supplementation on oxidative stress parameters: a systematic review and meta-analysis. Pharmacological Research. 2020 Nov;161:105210.
19	Elsabagh HH, Moussa E, Mahmoud SA, Elsaka RO, Abdelrahman H. Efficacy of melatonin in prevention of radiation-induced oral mucositis: a randomized clinical trial. Oral Diseases. 2020 Apr;26(3):566-572.
21	Lissoni P, Malugani F et al. Neuroimmunotherapy of untreatable metastatic solid tumors with subcutaneous low-dose interleukin-2, melatonin and naltrexone: modulation of interleukin-2-induced antitumor immunity by blocking the opioid system. Neuro Endocrinology Letters. 2002 Aug;23(4):341-4.
22, 79	Wang G, Pan S. Psychological Interventions and Sleep Improvement for Patients with Gastric Cancer: Effects on Immune Function, Inflammation, and Tumor Progression-A Randomized Controlled Trial. Annals of Surgical Oncology. 2025 Sep;32(9):6858-6876.
23	Sánchez-Barceló EJ, Mediavilla MD, Tan DX, Reiter RJ. Clinical uses of melatonin: evaluation of human trials. Current Medicinal Chemistry. 2010;17(19):2070-95.
24	Lissoni P, Chilelli M, Villa S, Cerizza L, Tancini G. Five years survival in metastatic non-small cell lung cancer patients treated with chemotherapy alone or chemotherapy and melatonin: a randomized trial. Journal of Pineal Research. 2003 Aug;35(1):12-5.
25, 26, 49, 85	Seely D, Legacy M et al. Adjuvant melatonin for the prevention of recurrence and mortality following lung cancer resection (AMPLCaRe): a randomized placebo controlled clinical trial. EClinicalMedicine. 2021 Feb 27;33:100763.
27, 52	Wang YM, Jin B et al. The efficacy and safety of melatonin in concurrent chemotherapy or radiotherapy for solid tumors: a meta-analysis of randomized controlled trials. Cancer Chemotherapy and Pharmacology. 2012 May;69(5):1213-20.
28	Kouhi Habibi N, Shabestani Monfared A et al. The protective effects of melatonin on blood cell counts of rectal cancer patients following radio-chemotherapy: a randomized controlled trial. Clinical and Translational Oncology. 2019;21(6):745-752.
29	Ghielmini M, Pagani O et al. Double-blind randomized study on the myeloprotective effect of melatonin in combination with carboplatin and etoposide in advanced lung cancer. British Journal of Cancer. 1999 Jun;80(7):1058-61.
30, 35, 48	Lissoni P. Is there a role for melatonin in supportive care? Supportive Care in Cancer. 2002 Mar;10(2):110-6.
31	Lissoni P, Paolorossi F et al. Is there a role for melatonin in the treatment of neoplastic cachexia? European Journal of Cancer. 1996 Jul;32A(8):1340-3.
32	Lissoni P, Paolorossi F et al. A randomized study of chemotherapy with cisplatin plus etoposide versus chemoendocrine therapy with cisplatin, etoposide and the pineal hormone melatonin as a first-line treatment of advanced non-small cell lung cancer patients in a poor clinical state. Journal of Pineal Research. 1997 Aug;23(1):15-9.
33	Persson C, Glimelius B, Rönnelid J, Nygren P. Impact of fish oil and melatonin on cachexia in patients with advanced gastrointestinal cancer: a randomized pilot study. Nutrition. 2005 Feb;21(2):170-8.
34, 38	Del Fabbro E, Dev R, Hui D, Palmer L, Bruera E. Effects of melatonin on appetite and other symptoms in patients with advanced cancer and cachexia: a double-blind placebo-controlled trial. Journal of Clinical Oncology. 2013 Apr 1;31(10):1271-6.
36	Lissoni P, Barni S et al. Decreased toxicity and increased efficacy of cancer chemotherapy using the pineal hormone melatonin in metastatic solid tumour patients with poor clinical status. European Journal of Cancer. 1999;35(12):1688-1692.
37	Lissoni P, Pittalis S et al. Prevention of cytokine-induced hypotension in cancer patients by the pineal hormone melatonin. Supportive Care in Cancer. 1996 Jul;4(4):313-6.
39	Palmer ACS, Zortea M et al. Clinical impact of melatonin on breast cancer patients undergoing chemotherapy; effects on cognition, sleep and depressive symptoms: A randomized, double-blind, placebo-controlled trial. PLoS One. 2020 Apr 17;15(4):e0231379.
40, 47, 57, 64	Innominato PF, Lim AS et al. The effect of melatonin on sleep and quality of life in patients with advanced breast cancer. Supportive Care in Cancer. 2016 Mar;24(3):1097-105.
41, 66	Lubas MM, Mandrell BN et al. A randomized double-blind placebo-controlled trial of the effectiveness of melatonin on neurocognition and sleep in survivors of childhood cancer. Pediatric Blood and Cancer. 2022 Jan;69(1):e29393.
42, 44, 53, 54, 56, 61	Fan R, Bu X et al. Effect of melatonin on quality of life and symptoms in patients with cancer: a systematic review and meta-analysis of randomised controlled trials. BMJ Open. 2022 Sep 14;12(9):e060912.
43	Yu ZY, Peng RY et al. Melatonin in cancer treatment. Cochrane Database of Systematic Reviews. 2025 Apr 30;4(4):CD010145.
45	Mukhopadhyay ND, Khorasanchi A et al. Melatonin Supplementation for Cancer-Related Fatigue in Patients With Early Stage Breast Cancer Receiving Radiotherapy: A Double-Blind Placebo-Controlled Trial. Oncologist. 2024 Feb 2;29(2):e206-e212.
46	Sedighi Pashaki A, Sheida F et al. A Randomized, Controlled, Parallel-Group, Trial on the Long-term Effects of Melatonin on Fatigue Associated With Breast Cancer and Its Adjuvant Treatments. Integrative Cancer Therapies. 2023 Jan-Dec;22:15347354231168624.
50	Lund Rasmussen C, Klee Olsen M et al. Effects of melatonin on physical fatigue and other symptoms in patients with advanced cancer receiving palliative care: a double-blind placebo-controlled crossover trial. Cancer. 2015 Oct 15;121(20):3727-36.
51	Chen WY, Giobbie-Hurder A et al. A randomized, placebo-controlled trial of melatonin on breast cancer survivors: impact on sleep, mood, and hot flashes. Breast Cancer Research and Treatment. 2014;145(2):381-388.
55, 63	Borazan H, Tuncer S, Yalcin N, Erol A, Otelcioglu S. Effects of preoperative oral melatonin medication on postoperative analgesia, sleep quality, and sedation in patients undergoing elective prostatectomy: a randomized clinical trial. Journal of Anesthesia. 2010 Apr;24(2):155-60.
58	Ben-David MA, Elkayam R, Gelernter I, Pfeffer RM. Melatonin for prevention of breast radiation dermatitis: a phase ii, prospective, double-blind randomized trial. Israeli Medical Association Journal. 2016 Mar-Apr;18(3-4):188-92.
59	Nissen ER, Neumann H et al. Interventions for insomnia in cancer patients and survivors-a comprehensive systematic review and meta-analysis. JNCI Cancer Spectrum. 2024 Apr 30;8(3):pkae041.
60	Kurdi MS, Muthukalai SP. The Efficacy of Oral Melatonin in Improving Sleep in Cancer Patients with Insomnia: A Randomized Double-Blind Placebo-Controlled Study. Indian Journal of Palliative Care. 2016 Jul-Sep;22(3):295-300.
62	Mendis R, Wong et al. Temazepam or Melatonin Versus Placebo for the Treatment of Insomnia in Advanced Cancer: A Three-Arm, Double-Blind, Phase III, Multicenter, Randomized Clinical Trial. Journal of Palliative Medicine. 2024 Oct;27(10):1368-1373.
65	Etedali A, Hosseni AK et al. Melatonin in the Management of Mood and Sleep Problems Induced by Androgen Deprivation Therapy in Prostate Cancer Patients: A Randomized Double-blinded, Placebo-controlled Clinical Trial. Iranian Journal of Pharmaceutical Research. 2022 Sep 30;21(1):e128817.
67, 73	Hansen MV, Halladin NL, Rosenberg J, Gögenur I, Møller AM. Melatonin for pre- and postoperative anxiety in adults. Cochrane Database of Systematic Reviews. 2015 Apr 9;2015(4):CD009861.
68, 69, 70, 71, 72	Madsen BK, Zetner D, Møller AM, Rosenberg J. Melatonin for preoperative and postoperative anxiety in adults. Cochrane Database of Systematic Reviews. 2020 Dec 8;12(12):CD009861.
74, 76	Andersen LP, Werner MU, Rosenberg J, Gögenur I. A systematic review of peri-operative melatonin. Anaesthesia. 2014 Oct;69(10):1163-71.
75	Hansen MV, Danielsen AK, Hageman I, Rosenberg J, Gögenur I. The therapeutic or prophylactic effect of exogenous melatonin against depression and depressive symptoms: a systematic review and meta-analysis. European Neuropsychopharmacology. 2014 Nov;24(11):1719-28.
77	Kiabi FH, Emadi SA, Jamkhaneh AE, Aezzi G, Ahmadi NS. Effects of preoperative melatonin on postoperative pain following cesarean section: a randomized clinical trial. Annals of Medical Surgery (London). 2021 May 12;66:102345.
78	Laflı Tunay D, Türkeün Ilgınel M et al. Comparison of the effects of preoperative melatonin or vitamin C administration on postoperative analgesia. Bosnian Journal of Basic Medical Sciences. 2020;20(1):117-124.
80	Veiga ECA, Simões R et al. Repercussions of melatonin on the risk of breast cancer: a systematic review and meta-analysis. Revista da Associação Médica Brasileira (1992). 2019 Jun 3;65(5):699-705.
81	Xu J, Huang L, Sun GP. Urinary 6-sulfatoxymelatonin level and breast cancer risk: systematic review and meta-analysis. Scientific Reports. 2017 Jul 13;7(1):5353.
82	Basler M, Jetter A et al. Urinary excretion of melatonin and association with breast cancer: meta-analysis and review of the literature. Breast Care (Basel). 2014 Jul;9(3):182-7.
83	Yang WS, Deng Q, Fan WY, Wang WY, Wang X. Light exposure at night, sleep duration, melatonin, and breast cancer: a dose-response analysis of observational studies. European Journal of Cancer Prevention. 2014 Jul;23(4):269-76.
84	Wang XS, Tipper S et al. First-morning urinary melatonin and breast cancer risk in the Guernsey Study. American Journal of Epidemiology. 2014 Mar 1;179(5):584-93.
86	Lissoni P, Brivio O et al. Adjuvant therapy with the pineal hormone melatonin in patients with lymph node relapse due to malignant melanoma. Journal of Pineal Research. 1996 Nov;21(4):239-42.
87	Zhao M, Wan J et al. The reduction in circulating melatonin level may contribute to the pathogenesis of ovarian cancer: a retrospective study. Journal of Cancer. 2016 Apr 27;7(7):831-6.
88	Poole EM, Schernhammer E, Mills L, Hankinson SE, Tworoger SS. Urinary melatonin and risk of ovarian cancer. Cancer Causes and Control. 2015 Oct;26(10):1501-6.
89	Sigurdardottir LG, Markt SC et al. Urinary melatonin levels, sleep disruption, and risk of prostate cancer in elderly men. European Urology. 2015 Feb;67(2):191-4.
90	Tai SY, Huang SP, Bao BY, Wu MT. Urinary melatonin-sulfate/cortisol ratio and the presence of prostate cancer: a case-control study. Scientific Reports. 2016 Jul 8;6:29606.

Melatonin for Cancer