Too Sour to be True? Tart Cherries ( Prunus cerasus ) and Sleep: a Systematic Review and Meta-analysis

Purpose for Review Sleep deprivation and insomnia are associated with mortality and morbidity worldwide. A pharmacological agent that improves subjective and objective measures of sleep, without significant side effects, remains nebulous. However, initial randomised controlled trials suggest Prunus cerasus (tart cherry) ingestion may be beneficial. This systematic review and meta-analysis evaluates the effect of Prunus cerasus on objective and subjective measures of sleep. Recent Findings We identified a total of 277 unique records, from which 8 studies of low-moderate methodological quality were included in the systematic review. Meta-analysis of subjectively recalled sleep efficiency (SE) and total sleep time (TST) were not significant. Objective SE, however, was significantly higher in the cherry cohort when compared to placebo with an effect size of 0.63 (95% CI 0.29–0.97, P < 0.01). There was low associated heterogeneity ( I 2 = 0%). Objective TST was significantly higher in the cherry cohorts, with a pooled effect size of 1.21 (95% CI 0.83–1.58, P < 0.01). There was high associated heterogeneity ( I 2 = 81.5%). Summary Whilst individuals may not subjectively experience a benefit, there is evidence to support significant improvements to total sleep time and sleep efficiency with the ingestion of Prunus cerasus using objective measures. Tart cherry may be the next frontier of sleep medicine and warrants further research.