OPINION: Over a third of Americans don’t spend enough hours in bed, which has serious health effects. Diet is an important and underestimated reason.
The future, my mother always said, belongs to those who get up early. L’avenir appartient à ceux qui se lèvent tot. That’s what she said when we went to the early ice-skating exercises on that cold winter morning growing up in Quebec. It turns out that science might prove it right – if not quite as it thought.
I am a researcher who specializes in understanding the relationships between diet, sleep, and health. Until around 2014, my lab focused on studying how too little sleep affects obesity. Our work showed that reducing sleep by about four hours per night for four nights resulted in an increase in food intake that amounted to about 300 calories per day (the equivalent of a McDonald’s cheeseburger). The cause, we found, is increased activity in the brain’s reward centers that are specific to food, along with changes in the hormones that control bloating. In other words, people who sleep less feel hungrier and tend to crave high-sugar and high-fat foods.
Then, in 2014, the U.S. Dietary Guidelines Advisory Committee – the group of scientists who make recommendations on what Americans should eat to be healthy – reached out to me to ask the opposite question: How does diet affect you? Sleep? That was an exciting question.
It is also a very important one. About 35 percent of Americans get less than the recommended minimum of seven hours of sleep per night; 10 to 30 percent suffer from a sleep disorder such as insomnia or sleep apnea. Insufficient sleep and insomnia have been linked to a variety of problems, ranging from mental illness to chronic illnesses such as type 2 diabetes and cardiovascular disease.
But for more and better sleep, it’s not always just about going to bed earlier: It turns out that diet is an underestimated factor in good or bad sleep.
Usually, people can pinpoint the food or drink triggers that contribute to poor sleep: drinking coffee too late in the day or having a large meal too close to bed are two obvious reasons that can disrupt sleep. What is less noticeable is how healthy choices made throughout the day can have a positive impact on sleep.
Our studies over the past seven years have shown that consuming more fiber and less saturated fat and sugar during the day leads to deeper, less disturbed sleep at night. It can be especially helpful to eat a Mediterranean diet high in fruits and vegetables, legumes, nuts, whole grains, and olive oil, and low in red and processed meat and whole dairy products. In our study, those who followed this diet were 1.4 times more likely to sleep well and 35 percent less likely to have insomnia.
Why? One of the reasons for this is that protein-rich foods such as nuts and seeds, fish, poultry and eggs contain tryptophan, an amino acid from which the sleep-regulating hormone melatonin is formed in the brain. Other foods – including tomatoes, pineapples, sour cherries, bananas, apples, vegetable oils, nuts, and animal products – contain melatonin themselves. In plants, melatonin serves as an antioxidant to prevent damage, while in animals it is used to regulate sleep (similar to that in humans). Consumption of such melatonin-rich foods can also increase your own melatonin levels, although there is little research on this.
Our work suggests that the effects of diet on sleep can be as strong or perhaps even stronger than mindfulness exercises (increasing awareness and acceptance of one’s thoughts and feelings, for example through meditation) or melatonin supplementation through pills. Studies show that melatonin supplements reduce sleep time by an average of four minutes; In one of our studies, eating a healthy diet reduced the time it takes to fall asleep by around 12 minutes and the overall quality of sleep was better.
Ultimately, poor sleep and poor diet can be a vicious circle: Lack of sleep leads to poor eating habits, which in turn leads to poor quality sleep. But we can break this cycle and turn it around. Eating well throughout the day could lead to firmer, more restful sleep – which in turn could help make better food choices.
Interestingly, this can be easier to achieve for early risers. People who refer to themselves as night owls and feel more late in the day than early in the day tend, on average, to eat fewer plant-based proteins, fruits, and vegetables. This evening preference is also (again on average) associated with a higher morbidity rate and earlier death.
So maybe the future belongs to those who get up early after all.
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Marie-Pierre St-Onge is a nutritionist and director of the Sleep Center of Excellence at Columbia University.
This article originally appeared in Knowable Magazine, an independent journalistic company owned by Annual Reviews. Sign up for the newsletter.