We know that lack of sleep is associated with changes in people’s diets, usually with reduced appetite. The opposite question also arises: can food affect sleep?
A study on the effect of kiwi on sleep showed that it seemed possible, kiwi helps with insomnia, but the explanation of the mechanism of this effect, proposed by the researchers, does not make any sense, since the serotonin contained in kiwi cannot cross the blood-brain barrier. We can eat as much serotonin as we want and it shouldn’t affect our brain chemistry. At the same time, melatonin can flow from our gut to the brain.
Melatonin is a hormone produced at night by the pineal gland located in the center of our brain to help regulate our circadian rhythm. Medicines containing melatonin have been used to help sleep in people moving to another time zone and have been used for about 20 years. But melatonin is not only produced by the pineal gland, it is also naturally present in edible plants.
This explains the results of a study on the effect of tart cherry juice on the sleep of older people with insomnia. The research team has previously investigated cherry juice as a sports recovery drink. Cherries have an anti-inflammatory effect on par with drugs such as aspirin and ibuprofen, so the researchers were trying to find out if cherry juice could reduce muscle soreness after exercise. During the study, some of the participants noted that they slept better after drinking cherry juice. It was unexpected, but the researchers realized that cherries are a source of melatonin.
Melatonin production tends to decrease with aging, and this may be one reason for the prevalence of insomnia among older adults. So the scientists took a group of elderly men and women suffering from chronic insomnia, and half of the old people were fed cherries and the other half were given a placebo.
They found that participants actually slept slightly better with cherry juice. The effect was modest but important. Some, for example, began to fall asleep faster and wake up less often after falling asleep in the middle of the night. Cherries helped without side effects.
How do we know it was melatonin? The scientists repeated the study, this time measuring melatonin levels, and indeed saw an increase in melatonin levels after cherry juice. Similar results were found when people ate seven different varieties of cherries, it increased their melatonin levels and actual sleep time. The consequences of the influence of all other phytonutrients contained in cherries cannot be excluded, they may have played a decisive role, but if melatonin is the sleeping agent, there are more powerful sources of it than cherries.
Melatonin is found in orange bell peppers, walnuts, and about the same amount in a tablespoon of flaxseed as in a tomato. The melatonin content of tomatoes may be one reason for the health benefits of traditional Mediterranean dishes. They have less melatonin than tart cherries, but people can eat far more tomatoes than cherries.
Several spices are quite a powerful source of melatonin: a teaspoon of fenugreek or mustard is equivalent to several tomatoes. Bronze and silver are shared by almonds and raspberries. And the gold belongs to the goji. The melatonin content in goji berries is off the charts.
Melatonin also helps in cancer prevention.
Michael Greger, MD