You may already know that how you eat before bed affects your sleep. Maybe you are still awake at 2 o'clock in the morning after drinking a cup of coffee with sweets. But did you know that the food choices you make during the day can affect your sleep at night?
In fact, growing evidence shows that overall diet affects sleep quality and contributes to insomnia.
I'm a nutritional epidemiologist and trained to look at population-level diets and how they affect health.
In the United States, the majority of the population suffers from poor sleep quality and problems such as sleep deprivation and sleep apnea, which is a blockage of the upper airway and stops breathing during sleep. At the same time, most Americans eat too much fat and processed foods, too little fiber, and too few fruits and vegetables.
Although it is difficult to determine whether these two trends are causally related, a growing number of studies show a link between sleep and diet and offer suggestions for a biological basis for this relationship.
How can nutrition and sleep quality be combined?
My colleagues and I wanted to better understand the relationship between sleep and diet in Americans 18 and older. So we found that people who followed the government's dietary guidelines for Americans got more hours of sleep.
Using a representative set of surveys collected from 2011 to 2016, we found that people who did not meet dietary recommendations, such as eating enough fruits, vegetables, legumes and whole grains, had longer sleep.
In a separate study, we followed more than 1,000 young people between the ages of 21 and 30; To help participants in an Internet-based dietary intervention study increase their daily fruit and vegetable intake. We found that people who increased their fruit and vegetable consumption over a three-month period had improved sleep quality and reduced symptoms of insomnia.
Studies by my group and others outside the United States show that a healthy diet is associated with better sleep quality and insomnia symptoms overall. These include the Mediterranean diet – a diet rich in plant foods, olive oil and seafood, and low in red meat and added sugar – and anti-inflammatory diets. It is similar to the Mediterranean diet, but it includes more attention on certain dietary components, such as flavonoids, a group of compounds found in plants that have been proven to reduce infectious biomaterials in the blood.
Analysis of food products and ingredients
Within a generally healthy diet, there are many individual foods and nutrients associated with sleep quality, with varying degrees of evidence.
For example, studies have shown that consuming fatty fish, dairy products, kiwi, cherries and other berries like strawberries and blueberries can lead to better sleep. One common way these foods affect sleep is by providing melatonin, an important modulator of sleep-wake cycles in the brain.
Fiber-rich foods, such as beans and oats, and certain protein sources, particularly those rich in the amino acid tryptophan, such as poultry, are associated with better sleep quality. Specific nutrients that may be beneficial include magnesium, vitamin D, iron, omega-3 fatty acids, and manganese. Some foods, such as salmon, are a source of many nutrients.
Complexity in development
An important caveat in many studies of individual foods and eating patterns is that most studies cannot easily identify the direction of associations.
In other words, it is difficult to know whether the association is the effect of sleep or diet. In fact, there can be a cyclical relationship where a healthy diet promotes good sleep, which in turn helps develop good eating habits.
In observational studies, there are also confounding factors, such as age and economic status, which may have important associations with sleep and diet.
Foods to avoid for healthy sleep
Looking for more sleep-inducing foods isn't enough to get better sleep. It is also important to avoid certain foods that can disrupt sleep. Here are the main culprits:
Saturated fats such as hamburgers, fried foods, and processed foods can induce low slow wave sleep, which is the most restful sleep.
Refined carbohydrates, such as those found in white bread and pasta, are metabolized quickly. If you eat these foods for dinner, you may wake up hungry.
Alcohol disrupts the quality of sleep. Although alcohol's sedative effect may initially make it easier to fall asleep, it can disrupt your sleep patterns, reduce REM sleep, or rapid eye movement, causing you to fall asleep earlier at night and lead to more nighttime awakenings.
Caffeine consumed six hours before bedtime blocks the sleep-inducing hormone adenosine, making it difficult to fall asleep.
Consuming too many calories on a regular basis can lead to weight gain, which is one of the strongest predictors of sleep apnea. As excess weight puts extra pressure on the diaphragm and lungs, it is important to narrow the airways when fat accumulates around the neck and throat.
Interestingly, our team recently showed that toxins in food or food packaging, such as pesticides, mercury and phthalates - chemicals used to make plastics - can affect sleep. Since toxins can be found in healthy and unhealthy foods, this study suggests that some foods may contain a mixture of beneficial and harmful compounds for sleep.
Meal time and gender considerations
The timing and sequence of meals, known as "eating" in sleep research, helps explain the relationship between healthy eating habits and good sleep.
In the United States, eating at regular times is associated with better sleep compared to regular meals. In addition, eating at night is often associated with eating junk food - such as junk food - and can lead to more disrupted sleep.
The final, most interesting part of this puzzle is that the relationship between diet and sleep often differs by gender. For example, the relationship between a healthy diet and insomnia symptoms may be stronger in women. One reason may be gender differences in sleep. In particular, women suffer from insomnia more than men.
The keys to good sleep
In general, there is no magic food or drink that improves sleep. It's best to focus on a healthy diet throughout the day, using a higher amount of calories at the beginning of the day.
And in addition to avoiding caffeine, alcohol and heavy meals two to three hours before going to sleep, the last hours of the day should include other sleep hygiene procedures.
This includes staying away from technology, reducing exposure to light, and creating a comfortable and relaxing sleep environment. In addition, it is very important to leave enough time for sleep and maintain a constant sleep and wake time.
This article was republished by The Conversation, an independent, non-profit news organization that provides facts and analysis to help you make sense of our complex world.
Author: Erica Jansen, University of Michigan .
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Erika Jansen receives funding from the National Heart Lung Blood Institute (NHBLI) through a K01 grant (K01HL151673).