Pilot Study of the Tart Cherry Juice for the Treatment of Insomnia and Investigation of Mechanisms.

BACKGROUND

Insomnia is common in the elderly and is associated with chronic disease, but use of hypnotics increases the incidence of falls. Montmorency tart cherry juice has improved insomnia by self-report questionnaire.

STUDY QUESTION

Is insomnia confirmed by polysomnography and is tryptophan availability a potential mechanism for treating insomnia?

STUDY DESIGN

A placebo-controlled balanced crossover study with subjects older than 50 years and insomnia were randomized to placebo (2 weeks) or cherry juice (2 weeks) (240 mL 2 times/d) separated by a 2-week washout.

MEASURES AND OUTCOMES

Sleep was evaluated by polysomnography and 5 validated questionnaires. Serum indoleamine 2,3-dioxygenase (IDO), the kynurenine-to-tryptophan ratio, and prostaglandin E2 were measured. In vitro, Caco-2 cells were stimulated with interferon-gamma, and the ability of cherry juice procyanidin to inhibit IDO which degrades tryptophan and stimulates inflammation was measured. The content of procyanidin B-2 and other major anthocyanins in cherry juice were determined.

RESULTS

Eleven subjects were randomized; 3 with sleep apnea were excluded and referred. The 8 completers with insomnia increased sleep time by 84 minutes on polysomnography (P = 0.0182) and sleep efficiency increased on the Pittsburgh Sleep Quality Index (P = 0.03). Other questionnaires showed no significant differences. The serum kynurenine-to-tryptophan ratio decreased, as did the level of prostaglandin E2 (both P < 0.05). In vitro, cherry juice procyanidin B-2 dose-dependently inhibited IDO.

CONCLUSIONS

Cherry juice increased sleep time and sleep efficiency. Cherry juice procyanidin B-2 inhibited IDO, increased tryptophan availability, reduced inflammation, and may be partially responsible for improvement in insomnia.