Melatonin supplements mimic the effects of your own naturally produced melatonin in promoting sleep. Research shows melatonin can have a substantial role in cancer outcomes and side effects.

How can melatonin help me? What the research says

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).

Learn more about how we research and rate therapies and practices.

Preclinical evidencetesting a drug, a procedure, or another medical treatment in isolated cells or in animals; preclinical evidence is considered only an initial indication of possible effects in people is summarized on Are you a health professional? ›

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) of better survival, tumor response, and remission among people with solid tumors treated with melatonin, mostly when combined with conventional treatmentthe cancer care offered by conventionally trained physicians and most hospitals; examples are chemotherapy, surgery, and radiotherapy

Advanced 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. on survival among people with advanced cancer treated with melatonin in 2 studies

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 better clinical response to chemotherapy among people with advanced cancer with enhanced melatonin levels

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.

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

Hormone imbalance

Preliminary evidence of hormone stimulation with 0.5 mg dose melatonin, but inhibition at 5.0 mg dose

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 hormone levels among postmenopausal women with breast cancer treated with melatonin in 2 preliminary studies

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) of lower inflammation in a general population treated with melatonin

No evidence of an effect on biomarkers assessing for immune function/inflammation after cancer resection among people with non-small cell lung cancer treated with melatonin in a large study

Oxidation

Good evidence of less oxidation in a general population treated with melatonin

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) of less oxidation among people with cancer treated with melatonin

Melatonin in combination with other complementary therapies

Melatonin and naltrexone: preliminary evidence of higher white blood cells counts among people with untreatable metastatic solid tumors treated with melatonin and naltrexone

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) of less chemotherapy-related toxicity among people treated with melatonin

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 better tolerance of chemotherapy among people with lung cancer treated with melatonin

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 adverse events after cancer resection among people with non-small cell lung cancer treated with melatonin in a large study

Anxiety

No evidence of an effect on anxiety after cancer resection among people with non-small cell lung cancer treated with melatonin in a large study

Blood-related side effects

Modest evidence of less severe reductions in blood cell counts during chemo/radiotherapy among people treated with 20 mg oral melatonin, but no evidence of an effect with 40 mg oral melatonin

Body composition or cachexia

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) of less wasting (cachexia) among people with advanced cancer treated with melatonin

Insufficient (conflicting) 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) of less weight loss among people with advanced cancer treated with melatonin

Cardiovascular symptoms

Modest evidence of less toxicity to the heart (cardiotoxicity) during chemotherapy among people with advanced cancer treated with melatonin

Preliminary evidence of lower incidence of low blood pressure among people with advanced cancer treated with melatonin

Changes in appetite

No evidence of an effect on appetite among people with cancer cachexia treated with melatonin in a preliminary study

Cognitive difficulties

Preliminary evidence of better cognitive performance during chemotherapy or hormone therapy among people with breast cancer treated with melatonin

Depression

Preliminary evidence of less depression among people with breast cancer treated with melatonin at doses higher than 3 mg

No evidence of an effect on depression after cancer resection among people with non-small cell lung cancer treated with melatonin in a large study

Fatigue

Good evidence of less fatigue during radio/chemotherapy among people with cancer treated with melatonin

Good evidence of less weakness or lack of energy (asthenia) among people with advanced metastatic cancer

No evidence of an effect on fatigue after cancer resection among people with non-small cell lung cancer treated with melatonin in a large study

No evidence of an effect on fatigue among people with advanced cancer treated with melatonin in a preliminary study

Hot flashes

No evidence of an effect on hot flashes among among postmenopausal women with breast cancer treated with 3 mg of melatonin in a preliminary study

Neurological side effects

Modest evidence of less neurotoxicity during radio/chemotherapy among people treated with melatonin

Oral symptoms

Modest evidence of less oral inflammation (oral mucositis or stomatitis) during radio/chemotherapy among people treated with melatonin

Pain

Preliminary evidence of less pain during treatment among people with cancer treated with melatonin

No evidence of an effect on pain after cancer resection among people with non-small cell lung cancer treated with melatonin

Quality of life and function

Insufficient (conflicting) evidence of better quality of life among people with cancer treated with melatonin

Sleep disruption

Preliminary evidence of better sleep quality without regard to treatment phase among people with cancer treated with melatonin

Insufficient (conflicting) evidence of better sleep quality after surgery among people treated with melatonin

Preliminary evidence of better sleep quality during cancer treatment among people treated with melatonin

Other side effects and symptoms

Preliminary evidence of less radiation dermatitis among people treated with a melatonin emulsion

Symptoms not specific to cancer

Good evidence of less anxiety while preparing for surgery among adults treated with melatonin, comparable to results with benzodiazepines

Good evidence of less anxiety after surgery among people treated with melatonin

No evidence of an effect on depression scores among people with depression treated with melatonin in a combined analysis of studies

Modest evidence of less pain from surgery not specific to cancer among people treated with melatonin

Preliminary evidence of better sleep quality but no evidence of an effect on anxiety or pain during intensive care among people treated with melatonin

Reducing cancer risk

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

Breast 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) of a higher risk of breast cancer among people with lower melatonin levels

Lung cancer

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) of lower risk of recurrence at 5 years after cancer resection among people with stage 3/4 non-small cell lung cancer treated with melatonin

Melanoma and other skin cancers

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 risk of melanoma recurrence among people treated with melatonin supplements

Preliminary evidence of less skin damage during sun exposure among people using a topical melatonin cream

Ovarian cancer

Preliminary evidence of a higher risk of ovarian cancer among people with lower melatonin levels

Prostate cancer

Preliminary evidence of a higher risk of prostate cancer or of advanced cancer among men with prostate cancer with lower melatonin levels

Resources related to evidence

TRC Natural Medicines

In-depth information, ratings of effectiveness and safety and evaluation of specific melatonin products; subscription required

Access the website

Keep reading about melatonin

Author

Nancy Hepp, MS

Lead Researcher and Program Manager
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Ms. Hepp is a researcher and communicator who has been writing and editing educational content on varied health topics for more than 20 years. She serves as lead researcher, program manager, and writer for CancerChoices. Her graduate work in research and cognitive psychology, her master’s degree in instructional design, and her certificate in web design have all guided her in writing and presenting information for a wide variety of audiences and uses. Nancy’s service as faculty development coordinator in the Department of Family Medicine at Wright State University also provided experience in medical research, plus insights into medical education and medical care from the professional’s perspective.

Nancy Hepp, MS Lead Researcher and Program Manager

Reviewers

Laura Pole, RN, MSN, OCNS

Senior Clinical Consultant
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Laura Pole is senior clinical consultant for CancerChoices. Laura is an oncology clinical nurse specialist who has been providing integrative oncology clinical care, navigation, consultation, and education services for over 40 years. She is the co-creator and co-coordinator of the Integrative Oncology Navigation Training at Smith Center for Healing and the Arts in Washington, DC. Laura also manages the “Media Watch Cancer News That You Can Use” listserv for Smith Center/Commonweal. In her role as a palliative care educator and consultant, Laura has served as statewide Respecting Choices Faculty for the Virginia POST (Physician Orders for Scope of Treatment) Collaborative as well as provided statewide professional education on palliative and end-of-life care for the Virginia Association for Hospices and Palliative Care.

For CancerChoices, Laura curates content and research, networks with clinical and organizational partners, brings awareness and education of integrative oncology at professional and patient conferences and programs, and translates research into information relevant to the patient experience as well as clinical practice.

Laura sees her work with CancerChoices as a perfect alignment of all her passions, knowledge and skills in integrative oncology care. She is honored to serve you.

Laura Pole, RN, MSN, OCNS Senior Clinical Consultant

Dugald Seely, ND, MSc

Physician, researcher, and CancerChoices advisor
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Dugald Seely, ND, MSc is a naturopathic doctor and clinician scientist living in Ottawa, Canada. Dr. Seely serves patients living with cancer in clinic and is active in research building on the base of evidence for integrative and naturopathic oncology. Helping to pioneer the delivery and development of integrative oncology, Dr. Seely is the founder and executive director of The Centre for Health Innovation (CHI); an adjunct professor at the University of Ottawa, Faculty of Medicine; executive director for research and clinical epidemiology at the Canadian College of Naturopathic Medicine; and president of the Oncology Association of Naturopathic Physicians (OncANP). Dr. Seely has led numerous clinical trials and synthesis research over the past 18 years and has published and presented internationally. Dugald is the father of two and most happy when spending time with his family in the wild outdoors.

Dugald Seely, ND, MSc Physician, researcher, and CancerChoices advisor

Last update: October 14, 2022

Last full literature review: October 2021

CancerChoices provides information about integrative in cancer care, a patient-centered approach combining the best of conventional care, self care and evidence-informed complementary care in an integrated plan cancer care. We review complementaryin cancer care, complementary care involves the use of therapies intended to enhance or add to standard conventional treatments; examples include supplements, mind-body approaches such as yoga or psychosocial therapy, and acupuncture therapies and self-care lifestyle actions and behaviors that may impact cancer outcomes; examples include eating health-promoting foods, limiting alcohol, increasing physical activity, and managing stress practices to help patients and professionals explore and integrate the best combination of conventionalthe cancer care offered by conventionally trained physicians and most hospitals; examples are chemotherapy, surgery, and radiotherapy and complementary therapies and practices for each person.

Our staff have no financial conflicts of interest to declare. We receive no funds from any manufacturers or retailers gaining financial profit by promoting or discouraging therapies mentioned on this site.

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