Switching to this more optimal diet could lead to noticeable improvements in your sleep in as little as two weeks, said Marie-Pierre St-Onge, an associate professor of nutritional medicine at Columbia University Irving Medical Center and the director of the Center of Excellence for Sleep and Circadian Research.
St-Onge has conducted dozens of clinical trials and other studies over the years examining the relationship between food and sleep. Her research has shown that what we eat influences how we sleep and that how we sleep in turn influences what we decide to eat the next day.
Poor diet may lead to poor sleep
Eating the wrong foods can disrupt your nightly sleep, and this in turn can spur physiological changes that cause you to crave and seek out junk food, creating a cycle of poor diet fuelling poor sleep and vice versa.
But eating the right foods can create a beneficial cycle where you sleep well and, as a result, you have fewer cravings for junk food and more of an appetite for the healthy foods that promote good sleep.
“When you have good sleep quality, it’s easier to make healthful choices related to your lifestyle behaviours,” said St-Onge, whose new book, Eat Better, Sleep Better, explains the relationship between diet and sleep.
“You make better food choices, but you also have more energy to exercise and be active, and you have a better overall mood and outlook in general.”
The hormones that support your sleep
Understanding how to eat in a way that improves your sleep starts with what St-Onge calls the two “must-have” sleep-supporting hormones. One of them is serotonin, which plays an important role in how well and how long you sleep at night, and the other is melatonin, which regulates your circadian rhythm and helps you fall asleep.
Our bodies naturally produce these hormones. But to synthesise them, we need the amino acid tryptophan, which we can get only from food because our bodies don’t produce it.
You’ve probably heard the old saying that eating turkey makes you sleepy because turkey is a great source of tryptophan. That’s only partially true. Turkey contains a lot of tryptophan, but so do a number of other foods. And it’s not exactly a fast-acting sedative. It can take four to five hours for a meal to make its way through your stomach and a few more hours for it to pass through your small intestine, which means that any tryptophan you consume takes a while to reach its final destination.
“The whole process of digestion, absorption and the shuttling of nutrients throughout the body where they can be synthesised into hormones and neurotransmitters takes some time,” St-Onge said. “But we need to have these building blocks available for the production of melatonin and its secretion for when the time comes.”
How to start a sleep-friendly diet
Only a fraction of the tryptophan that we consume makes its way into the brain, where it can be converted into serotonin and melatonin. That’s because tryptophan has to compete with other amino acids for absorption.
To ensure that your body has a steady supply of serotonin and melatonin, you should eat tryptophan-rich foods throughout the day, said St-Onge, and you should combine them with plant foods that contain a lot of fibre and complex carbohydrates.
Eating this way ensures that your body releases just enough insulin to shuttle amino acids that compete against tryptophan into your muscle and fat tissue, clearing the way for tryptophan to cross the blood brain barrier and be synthesised into melatonin and serotonin.
Some foods contain not only tryptophan, but modest amounts of melatonin, serotonin and other sleep-promoting nutrients, including magnesium, zinc, fibre and vitamin D:
- Tryptophan: Meat, poultry and seafood contain a lot of tryptophan, especially salmon, chicken breast, turkey, beef, pork, clams, tuna, eggs and yoghurt. Some examples of plant foods that contain plenty of tryptophan are tofu, white beans, lentils, edamame, oats, brown rice, barley, and sesame, pumpkin, chia, flax and sunflower seeds.
- Melatonin: Animal products such as beef, cheese, chicken, eggs, milk and seafood contain a lot of melatonin. But melatonin can also be found in fruits, vegetables and herbs, including apples, oranges, berries, bananas, mango, pineapple, cabbage, cucumbers, radishes, tomatoes, garlic and onions.
- Serotonin: Serotonin is found in many different plant foods, such as walnuts, pecans, avocados, bok choy, plantains, plums, spinach and wild rice. You can also find it in dark chocolate. One study that tested different types of chocolate found that dark chocolate with an 85% cocoa content had the highest levels of serotonin.
Read more: Why you should take magnesium for a better night’s sleep
In her book, St-Onge provides recipes and a meal plan for better sleep she devised with Kat Craddock, the editor-in-chief of Saveur, the gourmet food and travel magazine. Here are a few examples of these meals:
- Breakfast: A typical breakfast according to their plan might include plain yoghurt with muesli; quiche with salmon, goat cheese and spinach; or overnight oats with ginger, walnuts and fruit.
- Lunch: Lunch might include a turkey and black bean burrito bowl; marinated tofu with brown rice; or a salad with tuna, chickpeas and sesame-ginger vinaigrette.
- Dinner: At the end of the day, a good dinner would be something like sesame-ginger salmon with Asian greens; garlic shrimp with a fresh salad; or chickpea gemelli with butternut squash, walnuts, parmesan and oven-roasted broccoli.
St-Onge’s hope, she said, is that people ultimately understand that there’s a connection between everything we eat throughout the day and how we sleep at night.
“What you eat influences your physiology and biology but also your mental health,” she added. “I think sometimes people don’t think of sleep as originating from the brain, but it really does – and diet plays a big role.”