Junk food may impair sleep quality, study suggests. Eating meals too close to bedtime is notorious for prompting sleep issues, but another factor to consider throughout the day is what you’re eating. New research in the journal Obesity finds that just a few days of consuming unhealthy foods may also tank your sleep quality.
Researchers looked at 15 healthy, young men who ate two different types of meals in randomized order. Some of the group started with a high-fat, high-sugar diet for a week, then changed to a low-fat, low-sugar diet for the following week. Others in the group switched that order.
At the end of each week, participants spent a night in a sleep lab, which recorded variables like sleep duration and sleep phases. For all of them, sleep quality after a week of eating the “junk food” diet, laden with fat and sugar, was poor compared to sleep following a week of healthy eating.
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Deep sleep—also known as slow wave sleep—was the most notable shift, according to lead author Jonathan Cedernaes, Ph.D., associate professor in medical cell biology at Uppsala University in Sweden. He told Bicycling that this sleep stage is tied to memory processing and secretion of several hormones, including growth hormone, as well as metabolic regulation and insulin resistance.
“We found that exposure to the unhealthier diet disrupted a restorative part of slow-wave sleep, making this sleep stage more shallow,” he said. “Such changes can also be seen in aging or sleep
conditions, such as insomnia. Although we did not assess the impact on health outcomes in our study, we know from other work that intact deep sleep is associated with better longterm health.”
