The expression "you are what you eat" may sound quite cliché, but it perfectly reflects the interconnection of nutrition with a person's overall health and well-being.

We all know the benefits that a balanced diet has on our body and psyche, but something that many may overlook is the importance of nutrition in good, quality sleep.

A growing body of research published in recent years suggests that the foods we eat can affect how well we sleep at night, while the sleep patterns we adopt can influence our dietary choices. It's an interdependent relationship where one factor influences the other, and vice versa.

Researchers found that eating foods high in sugar, saturated fat, and processed carbohydrates can disrupt our sleep, while eating more vegetables, fiber, and foods rich in unsaturated fats—such as nuts, olive oil, fish, and avocados—seems to have the opposite effect, helping to promote healthy sleep.

Much of what we know about sleep and diet comes from large epidemiological studies that, over the years, have concluded that people who suffer from chronic sleep disorders tend to have poorer-quality dietary habits, with less protein, fewer fruits and vegetables, and a higher intake of added sugar from foods such as sugary drinks, desserts, and highly processed foods.

But by their nature, epidemiological studies can only show associations, not cause and effect. They can't explain, for example, whether poor diet precedes and leads to poor sleep or vice versa.

The food industries that fund research

To better understand the relationship between diet and sleep, some researchers have turned to randomized controlled trials in which they tell participants what to eat and then look for changes in their sleep.

Some of these trials, however, have been funded by the food industry, which may bias the results. A study funded by Zespri International , the world’s largest kiwifruit trader, for example, found that people who were assigned to eat two kiwifruits an hour before bed each night for four weeks had improvements in sleep onset, duration, and efficiency.

The study authors attributed their findings in part to the "abundance" of antioxidants in kiwifruit, however it is important to note that the study did not have a control group, so it is possible that any benefits could have resulted from the placebo effect.

Other studies funded by the cherry industry have found that drinking cherry juice can improve sleep in people with insomnia because it supposedly promotes tryptophan, one of the building blocks of the sleep-regulating hormone melatonin.

Tryptophan and its connection to sleep

Tryptophan is an amino acid found in many foods, including dairy and turkey, which is one of the commonly cited reasons why many of us feel so sleepy after the Christmas holidays.

But tryptophan must cross the blood-brain barrier to have any hypnotic effects, and in the presence of other amino acids found in food, it ends up largely unabsorbed. Studies show that consuming protein-rich foods like milk and turkey by themselves actually reduces tryptophan's ability to cross the blood-brain barrier.

One way to boost your tryptophan intake is to pair foods containing it with carbohydrates. This combination stimulates the release of insulin, which causes the muscles to absorb competing amino acids, in turn making it easier for tryptophan to pass into the brain, said Marie-Pierre St-Onge, an associate professor of nutritional medicine at Columbia University Irving.

Complex carbohydrates and the Mediterranean diet

Dr. St-Onge has spent years studying the relationship between diet and sleep . She suggests that rather than focusing on one or two specific foods with purported sleep-inducing properties, it’s better to focus on the overall quality of your diet. In a randomized clinical trial , she and her colleagues recruited 26 healthy adults and monitored what they ate for four days, providing them with regular meals prepared by nutritionists, while also monitoring how they slept at night. On the fifth day, the subjects were allowed to eat whatever they wanted.

Researchers found that eating more saturated fat and less fiber from foods like vegetables, fruits, and whole grains led to decreases in slow-wave sleep, which is the deep, restorative type of sleep.

In general, clinical trials have also found that carbohydrates have a significant impact on sleep: people tend to fall asleep much faster at night when they consume a diet high in carbohydrates compared to when they consume a diet high in fat or protein. This may have to do with carbohydrates helping tryptophan pass more easily into the brain.

But what matters most is the quality of the carbs. In fact, they can be a double-edged sword when it comes to sleep. Dr. St-Onge found in her research that when people eat more sugar and simple carbohydrates — like white bread, bagels, pastries, and pasta — they wake up more often during the night.

In other words, eating carbohydrates may help you fall asleep faster, but it's better to consume "complex" carbohydrates that contain fiber, which may help you get deeper and more restorative sleep.

[Read: How to increase deep sleep ]

An example of an eating pattern that may be optimal for better sleep is the Mediterranean diet, which emphasizes foods such as vegetables, fruits, nuts, seeds, legumes, whole grains, seafood, poultry, yogurt, herbs and spices, and olive oil.

Observational studies have found that people who follow this type of eating pattern are less likely to suffer from insomnia and short sleep, although more research is needed to confirm the association.

The two-way relationship between poor diet and poor sleep

The relationship between poor diet and poor sleep is bidirectional: scientists have discovered that as people lose sleep, they experience physiological changes that can prompt them to seek out junk food.

In clinical trials, healthy adults who are allowed to sleep only four or five hours a night end up consuming more calories and snacking more frequently during the day. They feel significantly hungrier and their preference for sweet foods increases .

In men, sleep deprivation stimulates increased levels of ghrelin , the so-called hunger hormone, while in women, sleep restriction leads to lower levels of GLP-1, a hormone that signals satiety.

"So in men, short sleep promotes greater appetite and desire to eat, and in women there is less of a signal that makes you stop eating," said Dr. St-Onge.

Changes also occur in the brain. Dr. St-Onge found that when men and women were restricted to four hours of sleep per night for five consecutive nights, they had greater activation in the brain's reward centers in response to pepperoni pizza, doughnuts, and sweets compared to healthy foods like carrots, yogurt, oatmeal, and fruit. After five nights of regular sleep, however, this pattern of stronger brain responses to junk food disappeared.

Another study , led by researchers at King's College London, also showed how getting enough sleep can increase your willpower to avoid unhealthy foods.

It was found that those who used to sleep little and went through a program to help them sleep more - resulting in about an extra hour of sleep each night - had improvements in their diet. The most striking change was that they cut about 10 grams of added sugar from their diet each day, which is the equivalent of about two and a half teaspoons.

Epilogue

The bottom line is that diet and sleep are intertwined. Improving one can help you improve the other and vice versa, creating a positive cycle where they perpetuate each other, said Dr. Redline, a senior physician at Brigham and Women's Hospital and a professor of sleep medicine at Harvard Medical School who studies diet and sleep disorders .

“The best way to approach health is to emphasize healthy eating and healthy sleep,” he added. “These are two very important health behaviors that can and do support each other.”

Tackle stress and insomnia with a gravity blanket

Gravity blankets are the most effective way to deal with insomnia and stress without medication, as they have been used for many decades to help people suffering from anxiety disorders, autism, and other sensory disorders.

How do they work?

They are designed to apply gentle, steady pressure to the entire body, which occupational therapists call “ Deep Tactile Pressure .” This steady pressure relaxes the nervous system and helps the body naturally increase levels of serotonin and melatonin (the hormones of happiness and sleep) while reducing levels of cortisol, which is responsible for stress.

As a result, the mind stops "racing", the heart rate drops, the mood improves and the body enters a state of complete relaxation.

Choose the one that weighs closest to 10% of your body weight and upgrade your sleep from the very first night.