A food source of melatonin and its precursor
Montmorency tart cherries contain naturally occurring melatonin along with tryptophan, the dietary amino acid the body uses to build its own melatonin. Small studies of tart cherry juice have reported modest increases in melatonin metabolites and minor improvements in sleep time or efficiency, which is the basis for its reputation as a whole-food sleep aid.
The amount of melatonin in cherries is small compared with a supplement tablet, so any benefit is thought to come from a combination of melatonin, tryptophan, and the fruit's polyphenols rather than a large melatonin dose alone.
How much to expect
The human evidence is limited to small trials, and effects on sleep are modest and not always consistent. Tart cherry is also studied for exercise recovery, where its anti-inflammatory polyphenols, not melatonin, are the proposed driver. It is reasonable to view it as a gentle, food-based option rather than a reliable treatment for a sleep disorder.
This is general educational information, not medical advice. Juices can be high in sugar, and anyone managing blood sugar or taking medication should consult a qualified professional.