Diet and Sleep
Much of what we know about sleep and diet comes from large epidemiological studies that, over the years, have found that people who suffer from consistently bad sleep tend to have poorer quality diets, with less protein, fewer fruits and vegetables, and a higher intake of added sugar from foods like sugary beverages, desserts and ultra-processed foods
Tryptophan is an amino acid found in many foods, including dairy and turkey, which is one of the reasons commonly given for why so many of us feel so sleepy after our Thanksgiving feasts. But tryptophan has to cross the blood-brain barrier to have any soporific effects, and in the presence of other amino acids found in food it ends up competing, largely unsuccessfully, for absorption. Studies show that eating protein-rich foods such as milk and turkey on their own actually decreases the ability of tryptophan to cross the blood-brain barrier.
One way to enhance tryptophan’s uptake is to pair foods that contain it with carbohydrates. That combination stimulates the release of insulin, which causes competing amino acids to be absorbed by muscles, in turn making it easier for tryptophan to cross into the brain, said Marie-Pierre St-Onge, an associate professor of nutritional medicine at Columbia University Irving Medical Center and the director of the Sleep Center of Excellence at Columbia.
Dr. St-Onge has found in her research that when people eat more sugar and simple carbs — such as white bread, bagels, pastries and pasta — they wake up more frequently throughout the night. In other words, eating carbs may help you fall asleep faster, but it is best to consume “complex” carbs that contain fiber, which may help you obtain more deep, restorative sleep.
“Complex carbohydrates provide a more stable blood sugar level,” said Dr. St-Onge. “So if blood sugar levels are more stable at night, that could be the reason complex carbohydrates are associated with better sleep.”
One example of a dietary pattern that may be optimal for better sleep is the Mediterranean diet, which emphasizes such foods as vegetables, fruits, nuts, seeds, legumes, whole grains, seafood, poultry, yogurt, herbs and spices and olive oil. Large observational studies have found that people who follow this type of dietary pattern are less likely to suffer from insomnia and short sleep, though more research is needed to confirm the correlation.
But the relationship between poor diet and bad sleep is a two-way street: Scientists have found that as people lose sleep, they experience physiological changes that can nudge 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 throughout the day. They experience significantly more hunger and their preference for sweet foods increases.
The takeaway is that diet and sleep are entwined. Improving one can help you improve the other and vice versa, creating a positive cycle where they perpetuate one another, said Dr. Susan Redline, a senior physician at the 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 a healthy diet and healthy sleep,” she added. “These are two very important health behaviors that can reinforce each other.”