Effect of tart cherry juice (Prunus cerasus) on melatonin levels and enhanced sleep quality.
Level 2 - randomized trial
Individual randomized, double-blind, placebo-controlled crossover trial
PubMed 22038497 · doi:10.1007/s00394-011-0263-7
What was done
Twenty healthy adult volunteers participated in a randomized, double-blind, placebo-controlled crossover trial consuming either tart Montmorency cherry juice concentrate or a placebo for 7 days. Sleep quality was evaluated using actigraphy and subjective questionnaires. Urinary 6-sulfatoxymelatonin was measured from sequential urine collections over 48 hours, and cosinor analysis was used to assess circadian rhythm metrics (mesor, acrophase, and amplitude).
What was found
Total urinary melatonin content was significantly elevated in the cherry juice group compared to baseline and placebo (P < 0.05). Cherry juice supplementation resulted in statistically significant increases in time in bed, total sleep time, and total sleep efficiency (P < 0.05). There was no difference in the timing of the melatonin circadian rhythm, though a trend toward higher mesor and amplitude was observed. Exact numerical values, effect sizes, and baseline metrics were not reported in the abstract.
Why it matters
This study shows that a dietary intervention with tart cherry concentrate can elevate urinary melatonin metabolites and improve actigraphy-measured sleep duration and efficiency in humans.
Limits
The sample size is very small (20 participants) and restricted to healthy adults without diagnosed sleep disorders. The intervention duration was short (7 days), and the abstract reports no specific numerical data, effect sizes, or confidence intervals.
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