You might already be aware that what you eat before bedtime impacts your sleep. Perhaps you’ve experienced being wide awake at 2 a.m. after having a cup of coffee with dessert. However, did you realize that your food choices during the day can also influence how well you sleep at night?

Indeed, increasing evidence indicates that our general eating habits can impact the quality of our sleep and potentially lead to insomnia.

As a nutritional epidemiologist, my expertise lies in analyzing dietary patterns across populations and understanding their impact on health.

In the U.S., many people struggle with inadequate sleep and sleep-related issues such as insomnia and obstructive sleep apnea, where the upper airway gets blocked, causing breathing to pause during sleep. Concurrently, the typical American diet is overloaded with fatty and processed foods, while lacking in fiber, fruits, and vegetables.

While it's challenging to confirm a direct causal relationship between sleep and diet, an increasing amount of research is highlighting connections between the two. This body of work also provides insights into the biological mechanisms that might explain these links.

My team and I aimed to explore the potential connection between sleep and diet among Americans aged 18 and above. We examined if those adhering to the government's Dietary Guidelines for Americans tend to achieve more hours of sleep.

Analyzing a nationally representative dataset of surveys from 2011 to 2016, we discovered that individuals failing to follow dietary guidelines, including eating sufficient amounts of fruits, vegetables, legumes, and whole grains, experienced shorter sleep durations.

In a different research project, we tracked over 1,000 adults between the ages of 21 and 30 who participated in an online dietary program aimed at boosting their daily intake of fruits and vegetables. Our findings revealed that participants who upped their consumption of fruits and vegetables during the three months experienced improvements in sleep quality and a decrease in insomnia symptoms.

Studies performed internationally by my team and other researchers indicate that improved sleep quality and reduced insomnia symptoms are linked to healthier dietary habits. Notable examples are the Mediterranean diet, which focuses on plant-based foods, olive oil, and seafood while minimizing red meat and added sugars, and anti-inflammatory diets. These diets are akin to the Mediterranean diet but place extra importance on specific elements like flavonoids, plant-based compounds known to decrease inflammatory biomarkers in the bloodstream.

Parsing the foods and nutrients

Within an overall healthy diet pattern, many specific foods and nutrients might be associated with better sleep quality, though the level of supporting evidence can vary.

Research has shown that eating foods like fatty fish, dairy, kiwi fruit, tart cherries, and berries such as strawberries and blueberries can improve sleep. These foods are believed to help by supplying melatonin, a crucial regulator of sleep-wake cycles in the brain.

Eating foods high in fiber, like beans and oatmeal, as well as protein sources rich in the amino acid tryptophan, such as poultry, can improve the quality of your sleep. Nutrients that may contribute positively to better sleep include magnesium, vitamin D, iron, omega-3 fatty acids, and manganese. Certain foods, such as salmon, are excellent because they contain multiple beneficial nutrients.

Untangling the complexity

A key limitation in much of the research on specific foods and dietary habits is the difficulty in clearly determining the direction of the relationships.

To put it differently, it's challenging to determine if the link is due to diet influencing sleep or if sleep is influencing diet. The truth is, it's probably a cyclical connection, where a nutritious diet enhances sleep quality, which then helps maintain healthy eating habits.

Observational studies come with potential confounding factors, including age and economic status, which may significantly correlate with both sleep and diet.

Foods to avoid for sleep health

Striving to consume more sleep-enhancing foods may not always suffice for achieving improved sleep. It’s equally crucial to steer clear of specific foods that might negatively affect your sleep quality. Below are some of the primary offenders:

• Saturated fats, commonly found in items like burgers, fries, and processed foods, might disrupt slow-wave sleep, the deepest and most rejuvenating stage of sleep.
• Refined carbohydrates, like those found in white bread and pasta, are broken down rapidly by the body. Eating these foods for dinner can cause you to wake up feeling hungry.
• Alcohol interferes with the quality of sleep. While its calming effects can help you drift off faster initially and sleep easier, it actually disrupts sleep by reducing REM (rapid eye movement) sleep in the initial stages of the night and causing more awakenings throughout the night.
• Consuming caffeine up to six hours before bedtime can interfere with your ability to fall asleep, as it blocks adenosine, the hormone responsible for making you feel sleepy.
• Consuming more calories than needed on a regular basis can result in weight gain, which is a significant risk factor for obstructive sleep apnea. Carrying extra weight can contribute to this condition as it places added strain on the diaphragm and lungs. Additionally, fat buildup around the neck and throat can constrict the airway, making the issue worse.

Interestingly, our team has recently demonstrated that harmful substances in food or its packaging, such as pesticides, mercury, and phthalates — chemicals utilized in plastic production — can impact sleep. These toxicants are present in both nutritious and less healthy foods, indicating that certain foods might offer a combination of elements that are both advantageous and detrimental to sleep.

Timing of meals and gender considerations

The timing and regularity of meals, referred to as "chrononutrition" in the field of sleep research, likely play a significant role in the link between nutritious diets and quality sleep.

In the U.S., sticking to regular meal times instead of indulging in random snacking has been linked to improved sleep. Additionally, eating late at night is often connected to the consumption of less healthy foods — like processed snacks — and may lead to more disrupted sleep.

An intriguing aspect of this puzzle is that the links between diet and sleep frequently vary by gender. For instance, the connection between healthy eating habits and insomnia symptoms seems to be more pronounced in women. One possible explanation for this is the differences in sleep patterns between genders. Specifically, women are more prone to experiencing insomnia compared to men.

Keys to a good night’s sleep

Overall, there isn't a single miracle food or beverage that can enhance your sleep. It's more beneficial to maintain healthy eating habits throughout the day, ensuring that you consume a larger portion of your calories earlier on.

Moreover, it's wise to steer clear of caffeine, alcohol, and heavy meals for a couple of hours before bedtime. Incorporating other effective sleep hygiene practices in the final hours of your day is also important.

These activities involve stepping away from electronic devices, minimizing exposure to light, and setting up a cozy and soothing sleep environment. Additionally, it's crucial to allocate sufficient time for sleep and to stick to a regular sleep schedule.