by In fact, more and more evidence shows that overall dietary patterns can affect sleep quality and contribute to insomnia.
I am a nutritional epidemiologist, trained to look at diets at the population level and how they affect health.
In the United States, a large percentage of the population suffers from poor sleep quality and sleep disorders such as insomnia and obstructive sleep apnea, a condition in which the upper airway becomes blocked and breathing stops during sleep. At the same time, most Americans eat far too much fatty and processed food, too little fiber and too few fruits and vegetables.
Although it is difficult to determine whether these two trends are causally linked to each other, more and more research shows the links between sleep and diet and provides clues about the biological basis of these relationships.
How diet and sleep quality can be intertwined
My colleagues and I wanted to gain a deeper understanding of the possible link between sleep and diet in Americans 18 and older. So we analyzed whether people who follow the government’s Dietary Guidelines for Americans get more hours of sleep.
Using a nationally representative data set of surveys collected from 2011 to 2016, we found that people who did not adhere to dietary recommendations, such as serving lots of fruits, vegetables, legumes and whole grains, had shorter sleep duration.
In a separate study, we followed more than 1,000 young adults between the ages of 21 and 30 who were enrolled in a web-based dietary intervention study designed to help them increase their daily servings of fruits and vegetables. We found that those who increased their fruit and vegetable consumption over a three-month period reported better sleep quality and reductions in insomnia symptoms.
Research by my group and others outside the US also shows that overall healthier dietary patterns are associated with better sleep quality and fewer symptoms of insomnia. 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. These are similar to the Mediterranean diet but include additional emphasis on certain components of the diet such as flavonoids, a group of compounds found in plants, which have been shown to lower inflammatory biomarkers in the blood.
Parse the foods and nutrients
Within overall healthy dietary patterns, there are many individual foods and nutrients that may be linked to sleep quality, with varying levels of evidence.
For example, studies have linked the consumption of fatty fish, dairy, kiwi fruit, tart cherries and other berries such as strawberries and blueberries to better sleep. One of the common ways these foods may affect sleep is by providing melatonin, an important modulator of sleep-wake cycles in the brain.
Fiber-rich foods such as beans and oatmeal and certain protein sources – especially those high in the amino acid tryptophan, such as poultry – are associated with higher quality sleep. Individual nutrients that may be beneficial include magnesium, vitamin D, iron, omega-3 fatty acids and manganese. Some foods such as salmon are rich sources of nutrients.
Complexity resolves
One important caveat of much research on individual foods, as well as dietary patterns, is that most studies cannot easily disentangle the direction of relationships.
In other words, it is difficult to know whether the association is the result of diet affecting sleep, or sleep affecting diet. The reality is that it’s probably a cyclical relationship, where a healthy diet promotes good quality sleep, which helps reinforce good dietary habits.
With observational studies, there may also be confounding factors, such as age and economic status, which may have important correlations with both sleep and diet.
Foods to avoid for sleep health
Aiming for a higher intake of sleep-promoting foods is not necessarily enough to get better sleep. It is also important to avoid certain foods that may be bad for your sleep. Here are some of the main culprits:
- Saturated fats, such as those in burgers and fries and processed foods, which are considered the most restorative, can lead to less slow-wave sleep.
- Refined carbohydrates, such as those in white bread and pasta, are metabolized quickly. If you eat these foods for dinner, they can make you hungry.
- Alcohol affects the quality of sleep. Although alcohol’s sedative effects can make it easier to fall asleep initially, it disrupts sleep patterns by shortening the amount of REM, or rapid eye movement, sleep in the first part of the night and resulting in more nighttime awakenings .
- Caffeine consumed even six hours before bed can make it difficult to fall asleep because it blocks the hormone adenosine, which promotes sleepiness.
- Consistent overconsumption of calories can lead to weight gain, one of the strongest predictors of obstructive sleep apnea. Being overweight is a factor because it can put extra pressure on the diaphragm and lungs, and it can also lead to a narrower airway if fat builds up around the neck and throat.
Interestingly, our group recently showed that toxins in food or food packaging, such as pesticides, mercury and phthalates – chemicals used to make plastics – can disrupt sleep. Since toxins can be found in both healthy and unhealthy foods, this research suggests that some foods can have a combination of both beneficial and detrimental components to sleep.
Timeliness of meals and gender issues
The timing and consistency of eating, known as “chronic nutrition” in the field of sleep research, is likely to help explain the links between healthy diets and good sleep.
In the United States, eating at regular meal times rather than random snacks was associated with better sleep. In addition, eating late at night is usually associated with less healthy food intake – such as processed snacks – and may lead to more fragmented sleep.
A final and very interesting piece of this puzzle is that the relationship between diet and sleep often differs by gender. For example, it appears that the associations between healthy dietary patterns and symptoms of insomnia may be stronger in women. One reason for this is gender differences in sleep. In particular, women are more likely to have insomnia than men.
The key to a good night’s sleep
Overall, there is no one magic food or drink that will improve your sleep. It is better to focus on overall healthy eating patterns throughout the day, with a higher percentage of calories consumed earlier in the day.
And, in addition to avoiding caffeine, alcohol and heavy meals in the two or three hours before bed, other good sleep hygiene practices should include the last few hours of the day.
These include turning off technology, reducing light exposure and a comfortable, relaxing environment for sleep. In addition, allowing enough time to sleep and maintaining a consistent bedtime and wake time are essential.
Erica Jansen, Assistant Professor of Nutritional Sciences, University of Michigan
This article is republished from The Conversation.
