In an article published online in the European Journal of Nutrition this week, Howatson et al. found that tart cherry juice from Montmorency cherries significantly increased melatonin levels in the body.
Since melatonin is the hormone that regulates sleep, the team found that people who consumed tart cherry juice concentrate not only slept for longer, but also had improved their quality of sleep.
The team said their findings could have notable benefits for people who have difficulty sleeping due to insomnia, shift work and jet lag.
Co-author Dr. Jason Ellis said:“Although melatonin is available over the counter in other countries, it is not freely available in the UK. What makes these findings exciting is that the melatonin contained in tart cherry juice concentrate is sufficient to elicit a healthy sleep response.”
In this small-scale study, Howatson et al. collaborated with the cherry juice firm Cherryactive to recruit 20 healthy volunteers, who drank a 30ml serving of either tart cherry juice or a placebo juice for 7 days.
Urine samples were collected from participants both before and during the study to determine melatonin levels, and subjects wore actigraphy watch sensors to monitor sleep and wake cycles and keep a ‘daily diary’ of sleeping patterns.
Strong evidence for sleep influence
Participants who drank tart cherry juice concentrate for one week were found to have a significant increase in urinary melatonin (+15-16 per cent) against the placebo group.
Actigraphy measurements also registered an increase of around 15 minutes to time spent in bed, an increase of 25 minutes in total sleep time and a 5-6 per cent increase in ‘sleep efficiency’ (a global measure of sleep quality).
Cherry juice drinkers also reported less napping time during the day (compared to their normal sleeping habits) and against placebo group napping times.
Asked about the significance of the findings, lead author Dr. Glyn Howatson (pictured) told BeverageDaily.com that little previous research had been done into the use tart cherries.
He said: “The data provides strong evidence that sleep can be influenced by the concentrate, and whilst other mechanisms can’t be completely ruled out, we think the melatonin is the principle reason for our observations.”
Howatson said the team’s study was only the second to examine sleep (5 published studies look at exercise recovery) and the first by Will Pigeon only showed modest sleep quality improvement for insomniacs, but that this was “subjectively examined”.
Pigeon’s team used a tart cherry and apple juice blend and “speculated that melatonin may be responsible [for the results] but did not measure it,” according to Howatson.
Benefits confined to tart juice
He noted that his team’s study used pure tart Montmorency cherry juice concentrate (with a greater concentration of phytochemicals, including melatonin).
“We showed a larger population with better experimental control (diet, for example) and a greater number of measures that are considered more valid (actigraphy, for example),” said Howatson.
He added: “We also looked at urinary melatonin and showed an increase, coupled with improved sleep time and sleep efficiency (quality) measured using actigraphy as a quantitative method.”
Future research could use polysomnography (a multi-parametric test of biophysiological changes), “the gold standard for examining sleep and sleep quality”, Howatson said.
“An experiment using this technology would provide good evidence, but as it stands 2 studies using 2 different, but nonetheless good quantities of the plant compounds, show a positive effect.
“The product is important. There are many watered down products that contain very little tart cherry juice, and there is no evidence for positive effects using these products, to our knowledge,” he added.
The team had no immediate plans to re-examine sleep, Howatson said, but that high levels of phytochemicals such as anthocyanins with anti-oxidative and anti-inflammatory effects were of real interest
“We plan to look at how this supplement might manipulate/reduce these effects (particularly from strenuous exercise),” he said, with sleep an important recovery factor the team could monitor.
The literature had already suggested positive effects of tart cherry juice consumption in terms of exercise recovery, Howatson added.
“There is also some indication that if we can manage inflammation and oxidative stress, it is feasible to apply this to clinical conditions that suffer from chronic inflammation and ox-stress, such as rheumatoid arthritis,” he said.
Title: ‘Effect of tart cherry juice (prunus cerasus) on melatonin levels and enhanced sleep quality’
Authors: G.Howatson J.Ellis, J.Tallent, P.Bell, B.Middleton, M.McHugh
Source: European Journal of Nutrition, published online ahead of print, DOI 10.1007/s00394-011-0263-7