Tart cherry juice may help insomniacs sleep: research

Researchers from Louisiana State University in Baton Rouge found that drinking Montmorency tart cherry juice twice a day for two weeks helped increase sleep time by nearly 90 minutes among older adults with insomnia.

They presented the results at the annual meeting of the American Society of Nutrition held this week in conjunction with the Experimental Biology 2014 meeting in San Diego, and submitted them for publication in a peer-reviewed journal. NutraIngredients-USA hasn’t yet seen the published data.

Insomnia – defined as trouble sleeping on average more than three nights per week – affects an estimated 23 to 34% of the population ages 65 and older. Though chronic sleeplessness can be an annoyance for some, long-lasting insomnia is linked to a higher prevalence of ailments from chronic pain and high blood pressure to type 2 diabetes and a decline of cognitive function (dementia) among the elderly.

For the randomized crossover clinical trial, seven older adults (average age of 68) with insomnia consumed 8 ounces of tart cherry juice twice daily for two weeks, followed by a two-week washout period, then a two-week period when another beverage was consumed (placebo). The researchers studied participants’ sleep in a controlled setting, using overnight polysomnography to evaluate such factors as sleep onset and duration.  Participants also completed questionnaires related to sleep, fatigue, depression and anxiety, and underwent blood work as well.   

Tart cherry juice drinkers slept over an hour longer each night vs. placebo​

The researchers found that those who drank the Montmorency tart cherry juice in the morning and at night were able to sleep more than an hour longer each night (averaging 84 minutes) compared to the placebo, and their sleep tended to be more efficient.

Montmorency tart cherries are a natural source of melatonin, a hormone that can help regulate the sleep-wake cycle.  Previous studies have suggested that tart cherry juice has sleep-enhancing benefits​, but Greenway and colleagues sought to explain why and understand if the benefits were due to the melatonin content or another component in Montmorency tart cherries. The ruby red pigments in tart cherry juice, known as proanthocyanidins, have also been purported to play a role.

According to the researchers, tart cherry juice helped to increase the availability of tryptophan, an essential amino acid and a precursor to serotonin that helps with sleep.  The juice was shown in cells to inhibit an enzyme (indoleamine 2,3 dioxygenase) that degrades tryptophan. Tryptophan degradation is a known predictor of insomnia and is also related to inflammation, said co-authors Jack Losso and John Finley, professors in the School of Nutrition and Food Sciences at Louisiana State University Agricultural Center. 

"Even though the amount of tryptophan in tart cherry juice is smaller than a normal dose given to aid sleep, the compounds in tart cherries could prevent the tryptophan from breaking down so it's able to work in the body more effectively,"​ co-author Frank L. Greenway, MD, director of the outpatient research clinic at the Pennington Biomedical Research Center at Louisiana State University, said. "These compounds may help to improve tryptophan bioavailability for serotonin synthesis, which could have a positive effect on sleep.  Increasing serotonin also helps improve mood and decrease inflammation."​

Greenway said he believes it's the unique combination of melatonin and tryptophan in Montmorency tart cherries that is likely contributing to the sleep benefits.  He and his colleagues conclude that drinking a glass of tart cherry juice in the morning and the evening may be a better and a safer way to treat insomnia than sleeping pills, for example.

Funding for this research was provided by the Cherry Marketing Institute.

Source: ​Experimental Biology 2014, San Diego, CA, April 28, 2014 ​
ClinicalTrials.gov​
“Tart Cherry Juice Increases Sleep Time in Older Adults with Insomnia”
Authors: Liu AG, Tipton RC, Pan W, Finley JW, Prudente A, Karki N, Losso JN, Greenway FL