Drinking a glass of tart or sour cherry juice in the morning and the evening can help older insomniacs sleep better and also stay safe, a new study suggests. Drinking Montmorency tart cherry (grown mostly in the US, Canada and France) juice twice a day for two weeks helped increase sleep time by nearly 90 minutes among older adults with insomnia. "Sleeping pills may be an option for younger insomniacs, but for older people these medications quadruple the risk of falling, which can lead to broken hips and, often, earlier death," said Frank L. Greenway of the Pennington Biomedical Research Center at Louisiana State University in the US. Montmorency tart cherries are a natural source of melatonin - a hormone that helps regulate the sleep-wake cycle. While previous studies have also suggested that tart cherry juice has sleep-enhancing benefits, the study set out to help explain why.They found that tart cherry juice helped to increase the availability of tryptophan, an essential amino acid and a precursor to serotonin that helps with sleep. "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 is able to work in the body more effectively," Greenway explained. These compounds may help to improve tryptophan bioavailability for serotonin synthesis, which could have a positive effect on sleep, he added. So it could be the unique combination of melatonin and tryptophan in Montmorency tart cherries that helps adult insomniacs sleep better.