Chris Kesser is not a reliable source of health information. As in many other cases (usually where people are advocating for supplement use, often to sell it to you), this is mechanistically plausible but untrue in the real world:Ski wrote:From Chris Kresser:Melatonin is another commonly used sleep aid. But I don’t recommend it for anything more than emergency, short-term use. Why? Because melatonin is a hormone. Taking any supplemental hormone disrupts our natural regulatory mechanisms of that hormone and throws our internal production of it out of whack. This can create dependence over time and disrupt our circadian rhythm, which is crucial not only to sleep, but to overall health.
Oral melatonin supplementation at 500mcg, over a period of a week in shift workers, did not influence basal secretion, as cessation for one day prior to measurements did not show differences when compared to secretion status prior to supplementation. Twenty-four hour melatonin levels in this study, when graphed, essentially overlapped, suggesting next to no variance. These results, indicating a lack of negative feedback, have been replicated with 2mg and 5mg of melatonin.
When a blind person supplemented a dose of 50mg in one case study (blind people being an example of a population with no sunlight-mediated melatonin production), this dose being 100-fold higher than the standard 500mcg, did not significantly influence basal secretion status. In this population, lower doses of 500mcg are also effective and without apparent negative feedback. ... [even when the] studies do control for persons with no conscious light perception.
Regulation of melatonin secretion from the pineal gland does not appear to be negatively influenced by melatonin supplementation over the long term (multiple days) and no negative feedback from melatonin supplementation (less natural secretion after a period of supplementation) has been observed.
24: Matsumoto M, et al The amplitude of endogenous melatonin production is not affected by melatonin treatment in humans . J Pineal Res. (1997)
25: Wright J, et al The effects of exogenous melatonin on endocrine function in man . Clin Endocrinol (Oxf). (1986)
26: Arendt J, et al Some effects of melatonin and the control of its secretion in humans . Ciba Found Symp. (1985)
27: Hack LM, et al The effects of low-dose 0.5-mg melatonin on the free-running circadian rhythms of blind subjects . J Biol Rhythms. (2003)
(It would have been better for this last study to have done same-patient pre- and post-testing; fortunately this is covered in the Examine.com citations).The overnight 6SMT [melatonin metabolite] excretion (between 22:00 and 10:00) in 15 patients who completed 6 months of daily [prolonged-release melatonin, 2 mg] administration and the following 2 weeks withdrawal of treatment was mean ± SD of 15.3 ± 7.7 μg, median 15 μg, range 4–30 μg. These levels were significantly higher than those of a large reference population of patients with insomnia of the same age group (mean ± SD of 9.5 ± 7.9 μg, range 0–47 μg/12-hour night; t-test, P < 0.01) and similar to those without insomnia of the same age group (mean ± SD of 18.1 ± 12.7 μg per 12-hour night) (Figure 3).17,19 Fourteen out of the 15 patients were considered to be within the normal range ... A clear diurnal rhythm in melatonin production was evident in these patients, with levels of 6SMT over daytime hours (10:00–22:00) of mean ± SD 9.80 ± 5.06, range 3–19 μg/12-hour day, which is significantly lower than the night-time levels (mean ± SD of 15.3 ± 7.7 μg, median 15 μg, range 4–30 μg; t-test, P < 0.01).
Lemoine P, Garfinkel D, Laudon M, Nir T, Zisapel N. Prolonged-release melatonin for insomnia - an open-label long-term study of efficacy, safety, and withdrawal. Ther Clin Risk Manag. 2011;7:301-11. doi: 10.2147/TCRM.S23036. Epub 2011 Jul 26. PubMed PMID: 21845053; PubMed Central PMCID: PMC3150476.
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