News & Views

How nutrition affects sleep

By Zach Pearl, PhD Staff


Sleep, like eating, is an essential part of life. The two are linked and influence one another. People who sleep less than 6 hours per night are more likely to consume energy-rich foods, consume higher portions of calories from fats or refined carbohydrates, consume lower portions of vegetables and fruits, and have more irregular meal patterns with more frequent snacks consumption than those who sleep more 1 . Certain foods can significantly interfere sleep, whereas eating the right foods in the hours before getting into bed may help to fall asleep faster and even improve the quality of sleep.

What are the worst foods for sleep?

Caffeine is a central nervous stimulant and most people use it in the morning to induce alertness or remain alert during the rest of the day. Caffeine (found in black tea, cocoa, chocolate, some soft drinks, and some drugs) has a negative effect on sleep, and it can extend the time to fall asleep, reduce the total sleep time and sleep efficiency, and worsen the sleep quality 2 . Caffeine has a half-life of five hours, which means that 25% of it will remain in the blood even 8-10 hours after consuming it. Thus, a cup of coffee or tea in the afternoon will keep some people from falling asleep at night.

A drink or two before bedtime can make people feel drowsy, leading many to believe it is actually beneficial for sleep. Indeed alcohol might help falling asleep faster but even just a couple of drinks can affect the quality of one’s sleep 3 . If individual is drinking on a regular basis, he may find himself waking up the next day feeling tired and not refreshed.

Artificial sweetener
Moderately to high doses of the artificial sweetener saccharin activate the orexin system, leading to wakefulness. It was shown that saccharin may cause sleep disorders by interrupting the biological clock 4 .

Spicy food
Spicy foods before bedtime can cause a major discomfort and digestion problems such as heartburn. Heartburn is especially problematic for people with gastroesophageal reflux disease, also known as acid reflux which is usually worsened when lying down to bed. Thus, spicy foods can lengthen the time to fall asleep and that spent awake during the night 5 .

Unhealthy fatty foods
When not getting enough sleep, one is more likely to crave high-fat, high-sugar foods the next day. Moreover, eating a high-fat diet further impacts sleep, and leads to fragmented sleep. In fact, an animal study revealed that eating fatty foods may lead to disrupted sleep and excessive daytime sleepiness 4 .

What are the best foods for sleep?

Certain foods, that include proteins, contain an amino acid called tryptophan that causes sleepiness. Carbohydrates make tryptophan more available to the brain, which is why carbohydrate-heavy meals can make people feel drowsy. Therefore, eating food that contains both a carbohydrate and protein is the best bedtime snack. Here is a partial list of food that is good for sleep:

Dairy products contain nutrients, particularly tryptophan, a building block to serotonin and melatonin, which play an important role in promoting sleep 1 . Therefore, eating milk and milk products has been considered helpful in improving sleep 6 .

and almonds
Walnuts are a good source of tryptophan and almonds are rich in magnesium, a mineral needed for quality sleep. A study found that when the body’s magnesium levels are too low, it is harder to stay asleep 7 .

Cherry juice
Drinking a glass of cherry juice could make one fall asleep faster, improve quality and sleep duration in adults who suffers from chronic insomnia 8 .

Chamomile tea / Passionfruit tea
A cup of chamomile tea or passionfruit tea 9 can help one sleep better. According to researchers, drinking such tea is associated with an increase of glycine, a chemical that relaxes nerves and muscles and acts like a mild sedative.

Jasmine rice
It was found that consuming jasmine rice four hours before bedtime shortens the time to fall asleep to half, probably because high-glycemic-index meals may increase the production of tryptophan 10 .

Bananas help promote sleep because they contain the natural muscle-relaxants magnesium and potassium and are also a good source for melatonin 11 .

To summarize, eating the right combination of foods before going to sleep and avoiding others may be beneficial in enhancing sleep. A balanced and varied diet that is rich in fresh fruits, vegetables, whole grains, and low-fat protein sources (all of which contain plenty of tryptophan, as well as group B vitamins, minerals, and unrefined carbohydrates) can improve sleep.

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