Among older adults with insomnia, tart cherry juice increases sleep time by nearly 90 minutes, says study.
For the randomized crossover clinical trial, seven older adults (average age 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).
Co-author Frank L. Greenway, MD, director of the outpatient research clinic at the Pennington Biomedical Research Center at Louisiana State University, and his colleagues studied their slumber in a controlled setting, using overnight polysomnography to evaluate sleep efficiency, such as sleep onset and duration. Participants also completed questionnaires related to sleep, fatigue, depression and anxiety. Additionally, blood work was conducted on each participant.
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.
The researchers believe the ruby red pigments in tart cherry juice, known as proanthocyanidins, also play a role. These natural polyphenolic compounds are especially abundant in Montmorency tart cherries.
In the study, 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.