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Effect of tart cherry juice (Prunus cerasus) on melatonin levels and enhanced sleep quality

PainSci » bibliography » Howatson et al 2012
Tags: sleep, nutrition, self-treatment, treatment

One article on PainSci cites Howatson 2012: Vitamins, Minerals & Supplements for Pain & Healing

PainSci notes on Howatson 2012:

A small pilot trial of tart cherries for insomnia in 20 subjects, comparing to a placebo and measuring sleep quality and melatonin levels. The conclusion is positive, but the data is mediocre at best: small effects that are barely statistically significant. It's not a negative study, but it's not exactly a convincing positive either.

Common issues and characteristics relevant to this paper: ?Scientific papers have many common characteristics, flaws, and limitations, and many of these are rarely or never acknowledged in the paper itself, or even by other reviewers. I have reviewed thousands of papers, and described many of these issues literally hundreds of times. Eventually I got sick of repeating myself, and so now I just refer to a list common characteristics, especially flaws. Not every single one of them applies perfectly to every paper, but if something is listed here, it is relevant in some way. Note that in the case of reviews, the issue may apply to the science being reviewed, and not the review itself.

  1. Risk of inadequate statistical power.
  2. Declares statistical significance without acknowledging low effect sizes. Major foul.
  3. Damned with faint praise — technically positive results (at least partially) that don’t actually impress.

original abstract Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

BACKGROUND: Tart Montmorency cherries have been reported to contain high levels of phytochemicals including melatonin, a molecule critical in regulating the sleep-wake cycle in humans. PURPOSE: The aim of our investigation was to ascertain whether ingestion of a tart cherry juice concentrate would increase the urinary melatonin levels in healthy adults and improve sleep quality. METHODS: In a randomised, double-blind, placebo-controlled, crossover design, 20 volunteers consumed either a placebo or tart cherry juice concentrate for 7 days. Measures of sleep quality recorded by actigraphy and subjective sleep questionnaires were completed. Sequential urine samples over 48 h were collected and urinary 6-sulfatoxymelatonin (major metabolite of melatonin) determined; cosinor analysis was used to determine melatonin circadian rhythm (mesor, acrophase and amplitude). In addition, total urinary melatonin content was determined over the sampled period. Trial differences were determined using a repeated measures ANOVA. RESULTS: Total melatonin content was significantly elevated (P < 0.05) in the cherry juice group, whilst no differences were shown between baseline and placebo trials. There were significant increases in time in bed, total sleep time and sleep efficiency total (P < 0.05) with cherry juice supplementation. Although there was no difference in timing of the melatonin circardian rhythm, there was a trend to a higher mesor and amplitude. CONCLUSIONS: These data suggest that consumption of a tart cherry juice concentrate provides an increase in exogenous melatonin that is beneficial in improving sleep duration and quality in healthy men and women and might be of benefit in managing disturbed sleep.

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