Melatonin, Sleep, and Prostate Cancer


At a recent prostate cancer conference scientists presented the results of a study suggesting the beneficial effects of melatonin in reducing the risk of advanced prostate cancer in up to 75% of participants with higher melatonin levels compared to those with low melatonin.

The Study Details

  • 928 men from Iceland were studied
    • Men who had higher levels of a melatonin metabolite, 6-sulfatoxymelatonin, experienced a 75% lower risk of advanced prostate cancer
    • 31% of men with higher melatonin levels had lower overall prostate cancer risk
    • 65% of the men had either difficulty falling a sleep, staying asleep or taking medication for sleep.
    • Men who had sleep problems experienced lower melatonin levels
    • Some foods and herbs contain moderate levels of melatonin including: feverfew (Tanacetum parthenium), St. John’s wort (Hypericum perforatum), and huang-qin (Scutellaria baicalensis), oats, rice bran, sweet corn, wheatgrass juice, ginger, tart cherries and bananas.


    What is Melatonin? What does it do?

    Melatonin is a hormone released by an area in the middle of your brain called the pineal gland and produced only at night in darkness while you sleep. Melatonin is important for the body’s natural and inherent processes during your circadian rhythm, also known as the 24-hour sleep-wake cycle. There is virtually no melatonin produced during the day.

    Circadian rhythm manages your body's release of hormones, temperature, blood pressure and sleep-wake cycle throughout a 24-hour cycle. These circadian rhythms are influenced by environmental conditions, dark-light cycles, and time zones. "Jet-lag" is an example of circadian rhythm disruption.

    In addition to setting your “body clock,” melatonin is a powerful antioxidant, possibly even more powerful than vitamin E (Pieri et al. 1994).

    What's the link between Sleep, Melatonin, and Prostate Cancer?

    In laboratories prostate cancer cells promotion and acceleration have been inhibited with melatonin exposure. The inhibitory effect of melatonin on androgen-sensitive prostate tumors was first demonstrated in male rats. (Buzzell et al. 1988)

    In humans, the effect of melatonin on prostate serum antigen (PSA) levels was evaluated in prostate cancer patients by examining cancer tissue biopsy and blood serum.  

    Two outcomes were observed in this study: 

    1. Melatonin receptors were found in prostate tumors; and
    2. Based on PSA measurements, it was shown that administration of melatonin (5 mg/day at night) induced stabilization of prostate cancer disease, thus suggesting that melatonin had anti-cancer action in prostate cancer patients. (Shiu et al. 2003)

    Epidemiological studies have revealed that compared with the normal population, the incidence of prostate cancer in men with reduced sightedness (and presumably a higher melatonin secretion) is low, although the decreases in cancer incidence were not as profound as those that have been observed for women with breast cancer who also have reduced sightedness. (Pukkala el al. 2006)

    Poor sleep patterns are associated with increased prostate cancer risk, and poor sleep patterns may be due to lack of melatonin production. 

    In a study of over 2400 undiagnosed who reported sleep problems, including difficulty falling asleep and staying asleep, had up to a twofold increased risk for prostate cancer. Further, there was more than a threefold increase in risk for advanced prostate cancer associated with “very severe” sleep problems. (Sigurdardottir et al. 2013)

    The Takeaway

    Melatonin has benefits, and in my opinion should be considered as part of a comprehensive anti-cancer lifestyle and supplementation program particularly in prostate cancer patients who also suffer from a sleep disorder like insomnia. 

    A dosing of 3 mg of melatonin thirty minutes before bedtime is appropriate for men with low-grade prostate cancer. Those with advanced prostate cancer may want to consider upping the dose to 20 mg. Both of these suggested dosages have proven to be safe in studies (Srinivasan et al. 2008). 

    Clinically, however, a few of my patients report a feeling of grogginess in the morning with even low dosages of melatonin. So be aware, as you may be more sensitive to this supplement. As always, it best to check with your naturophathic or integrative physician.

    By the way, for you "road warriors" out there, in melatonin helps to alleviate jet-lag symptoms, particularly if taken at the bedtime of the arrival destination in healthy men and women (Claustrat et al. 1995). As does exercise.


    Pieri C, Marra M, Moroni F, Recchioni R, Marcheselli F (1994). “Melatonin: a peroxyl radical scavenger more effective than vitamin E”. Life Sci. 55 (15): PL271–6.

    Poeggeler B, Saarela S, Reiter RJ, Tan DX, Chen LD, Manchester LC, Barlow-Walden LR (November 1994). “Melatonin – a highly potent endogenous radical scavenger and electron donor: new aspects of the oxidation chemistry of this indole accessed in vitro”. Ann. N. Y. Acad. Sci. 738: 419–20.

    Buzzell GR. Studies on the effects of the pineal hormone melatonin on an androgen-insensitive rat prostatic adenocarcinoma, the Dunning R 3327 HIF tumor. J Neural Transm. 1988;72:131-140.

    Shiu SY, Law IC, Lau KW, Tam PC, Yip AW, Ng WT. Melatonin slowed the early biochemical progression of hormone-refractory prostate cancer in a patient whose prostate tumor tissue expressed MT1 receptor subtype. J Pineal Res. 2003;35:177-182.

    Pukkala E, Ojamo M, Rudanko SL, Stevens RG, Verkasalo PK.Does incidence of breast cancer and prostate cancer decrease with increasing degree of visual impairment. Cancer Causes Control. 2006;17:573-576.

    Sigurdardottir LG, Valdimarsdottir UA, Mucci LA, Fall K, Rider JR, Schernhammer E, Czeisler CA, Launer L, Harris T, Stampfer MJ, Gudnason V, Lockley SW. Sleep disruption among older men and risk of prostate cancer. Cancer Epidemiol Biomarkers Prev. 2013 May;22(5):872-9.

    Srinivasan V, Spence DW, Pandi-Perumal SR, Trakht I, Cardinali DP. Therapeutic actions of melatonin in cancer: possible mechanisms.nIntegr Cancer Ther. 2008 Sep;7(3):189-203.

    Claustrat B, Geoffriau M, Brun J, Chazot G. Melatonin in humans: A biochemical marker of the circadian clock and an endogenous synchronizer. Neurophysiol Clin. 1995;25:351-359.