People who drank cherry juice twice daily were found to have longer sleep time, spent more time in bed, and had a better ‘sleep efficiency’, according to findings published in the European Journal of Nutrition.
The study supports a number of other studies reporting the potential benefits of cherries, and tart cherries, in particular. Several studies have reported that supplementation with cherries or its juice may boost recovery from exercise.
The new study is claimed to be the first to show “direct evidence that dietary supplementation with a tart Montmorency cherry juice concentrate increases circulating melatonin and can provide modest improvements in sleep time and quality in healthy adults with no reported disturbed sleep.
“Although the interaction of other phytochemicals cannot be completely ruled out, these data provide a mechanism of action for the previously conjectural reports of improved sleep quality with cherry juice supplementation,” wrote researchers from Northumbria University and the University of Surrey in England, and the University of Johannesburg in South Africa.
“Subsequently, Montmorency tart cherry juice concentrate might therefore present a suitable adjunct intervention for disturbed sleep across a number of scenarios in healthy and symptomatic individuals.”
The study involved 10 healthy men and 10 healthy women with a mean age of 26.6 and a mean BMI if 24.7 kg/m2. The participants were randomly assigned to consume either the tart cherry concentrate or placebo for seven days.
A 30 ml serving of tart Montmorency cherry juice (Prunus cerasus) concentrate (Cherry Active, UK) – containing the equivalent of 90-100 cherries – was given in the morning and one in the evening, and diluted with 200 ml of water.
Results showed that urine levels of melatonin increased following tart cherry consumption, while no such increases were observed in the placebo group.
Improvements in sleep measures were also reported by the researchers. Specifically, sleep efficiency increased by 5-6%, while total sleep time increased by an average of 34 minutes per night, compared with a decline in the placebo group.
Commenting on the potential mechanism, the researchers note that tart Montmorency cherries are claimed to contain high levels of phytochemicals including melatonin.
However, they also note that melatonin may not be the only explanation, “given that sleep regulation is also influenced by pro-inflammatory cytokines.
“Tart cherries have been shown to contain numerous phenolic compounds that have anti-inflammatory and antioxidant properties that can increase antioxidant capacity.
“Furthermore, cherry juice has been shown to decrease oxidative stress and inflammation following strenuous exercise making it possible that these antioxidant and/or anti-inflammatory properties modulated indices of sleep in this study, although this remains to be demonstrated in an experimental model.”
Source: European Journal of Nutrition
Published online ahead of print, doi: 10.1007/s00394-011-0263-7
“Effect of tart cherry juice (Prunus cerasus) on melatonin levels and enhanced sleep quality”
Authors: G. Howatson, P.G. Bell, J. Tallent, B. Middleton, M.P. McHugh, J. Ellis