Insomnia is a common condition in the elderly that can lead to a reduced quality of life and adverse outcomes.  Insomnia is associated with an increased prevalence of medical disorders including hypertension, type-2 diabetes, chronic pain, and a decline in cognitive function. Among various food remedies to help with insomnia, tart cherry juice has been reported to have a positive effect on a good night of sleep.

 

    Losso et al. (1) conducted a randomized, double-blind, placebo-controlled cross-over study to test the effectiveness of the tart cherry juice of known procyanidin content on sleep quality in older adults. Eight healthy male or female subjects (5 females, 3 males, age 68 ± 9 years) with chronic insomnia drank tart cherry juice containing a measured level of procyanidin (Procyanidin B-2 content is 451.56 mcg/ml) or a placebo juice in the morning and 1–2 hours before bedtime for 14 days. After a 2-week washout period, the subjects were crossed over to the tart cherry juice or the placebo they did not take in the first 2-week testing period, and the 2-week testing period was repeated. The cherry juice treatment extended sleep time by 84 minutes (p = 0.0182) and improved the Habitual Sleep Efficiency (p = 0.03).

 

    The authors suggested that since tryptophan, a precursor of serotonin, which reduces sleep latency in humans, tryptophan is degraded by the enzyme indoleamine 2, 3-dioxygenase (IDO) to produce kynurenine. The ratio of kynurenine to tryptophan is a measure of tryptophan degradation, a lower value suggesting decreased tryptophan degradation (1).

 

    The study results showed that the kynurenine-to-tryptophan ratio was reduced in the cherry juice condition (p < 0.05), indicating inhibition of IDO with a reduction in the degradation of tryptophan. The level of prostaglandin E2 (PGE2), a marker of inflammation, was also dose-dependently reduced (p < 0.05) (1).

 

    Pigeon et al. (2) performed a cross-over study exploring the effect of tart cherry juice (240 mL twice a day) or placebo over 2 weeks on insomnia in 15 older adults (aged 72 ± 5 years) with chronic insomnia who were otherwise healthy with a 2-week washout period between cross-over arms. They also reported statistically significant improvement during the cherry juice consumption in the Insomnia Severity Index from 15.5 at baseline to 13 after cherry juice, and improvement in waking after sleep onset from 79 minutes to 62 minutes after cherry juice.

 

    Howatson et al. (3) evaluated sleep quality in 20 healthy exercising volunteers between the ages of 18 and 40 years (26 ± 5 years). They used actigraphy to access the endpoints and gave 30 mL of tart cherry juice concentrate twice a day for 7 days or a placebo in a cross-over trial with a 2-week washout period between study arms. The cherry juice condition had a statistically significant increase of time in bed (25 minutes), total sleep time (34 minutes), and sleep efficiency (5%–6%). The urinary degradation product of melatonin increased statistically (~17%) in the cherry juice condition.

 

    Tart cherry is a rich food source for melatonin. Melatonin is postulated to treat insomnia, by restoring disturbed circadian rhythms. Tart cherry also contains tryptophan, a precursor for serotonin, promoting sleep. Tart cherries also contain many phytonutrients including the phenolic acids—chlorogenic acid, caffeic acid, and ellagic acid—and the flavonoids—isorhamnetin, kaempferol, quercetin, catechin, epicatechin, procyanidins, and anthocyanins.  Anthocyanins are the main component of the phenolic compounds found in tart cherries. All these phytonutrients can provide an anti-inflammatory effect and promote sleep via the inhibitory mechanism as proposed in Losso's study using procyanidin B2 as a biomarker for tryptophan degradation.

 

    The studies that examined the effectiveness of tart cherry juice on sleep in both young and older adults showed that tart cherry juice is an effective treatment for insomnia. Keep tart cherry in mind when you are looking for various foods that can help you with a good night's sleep.

 

References:

1. Losso, J. N., Finley, J. W., Karki, N., Liu, A. G., Prudente, A., Tipton, R., … Greenway, F. L. (2018). Pilot Study of the Tart Cherry Juice for the Treatment of Insomnia and Investigation of Mechanisms. American Journal of Therapeutics, 25(2), e194–e201.

2. Pigeon, W. R., Carr, M., Gorman, C., & Perlis, M. L. (2010). Effects of a Tart Cherry Juice Beverage on the Sleep of Older Adults with Insomnia: A Pilot Study. Journal of Medicinal Food, 13(3), 579–583.

3. Howatson G, Bell PG, Tallent J, et al. (2012). Effect of tart cherry juice (Prunus cerasus) on melatonin levels and enhanced sleep quality. Eur J Nutr, 51:909–916.