Study Shows Junk Food Consumption Could Impact Deep Sleep Quality

Uppsala University researchers have concluded that a diet rich in junk food can have a detrimental effect on the quality of deep sleep. Their study suggests that dietary habits may need to be factored in when examining conditions such as insomnia and aging, known to influence sleep quality.

This recent investigation undertaken by Uppsala University scrutinized the effect of junk food on sleep. In a randomized process, healthy individuals were given diets of varying healthfulness. The outcome showed a reduction in the quality of deep sleep for those consuming the less healthy diet compared to those on a healthier diet.

The study findings have been recently published in the Obesity journal.

There have been several epidemiological studies establishing a connection between diet and alterations in sleep patterns. Nevertheless, only a few studies have directly investigated diet’s impact on sleep, often done by having participants consume different diets in a randomized sequence.

Jonathan Cedernaes, MD, Ph.D., and Associate Professor in Medical Cell Biology at Uppsala University, noted, “Both poor diet and poor sleep raise the risk of several public health conditions. Since our diet significantly impacts our health, we decided to explore if different diets could induce changes to our sleep.”

Previous epidemiological studies have linked diets high in sugar to poor sleep. Yet sleep is a complex interplay of physiological states, as explained by Cedernaes: “Deep sleep, for instance, can be influenced by our dietary choices. However, no past study compared the quality of sleep when following an unhealthy diet versus a healthy diet. It’s noteworthy that sleep is highly dynamic, consisting of different stages serving different functions, like deep sleep regulating hormone release.”

In this study, the participants’ sleep was tracked over several days in a sleep laboratory, limiting the study to just 15 individuals. These healthy, normal-weight young men took part in two sessions. The participants’ sleep habits, which were normal and within the recommended range (average seven to nine hours per night), were screened.

The participants were given both healthier and unhealthier diets in a random sequence. The diets, despite their health differences, had the same caloric content, adjusted for each participant’s daily requirements. The unhealthier diet contained higher sugar and saturated fat content and more processed foods. The participants’ sleep, activity, and meal schedules were individually tracked over a week while consuming each diet.

Post-diet, the participants’ sleep was assessed in a sleep laboratory, where brain activity was monitored. Interestingly, no differences in sleep duration or the time spent in different sleep stages were observed between the two diets. But the team noted that deep sleep showed less slow-wave activity, an indicator of restorative sleep, after consuming junk food compared to healthier food.

The researchers have yet to understand the duration of these sleep effects caused by an unhealthy diet. “We’re interested in carrying out functional tests, such as checking if memory function, largely regulated by sleep, can be affected, and determining how long-lasting these effects may be. At present, we don’t know which elements in the unhealthy diet worsened deep sleep quality,” stated Cedernaes.

The study, titled “Exposure to a more unhealthy diet impacts sleep microstructure during normal sleep and recovery sleep: A randomized trial,” was authored by Luiz Eduardo Mateus Brandão, Alexandru Popa, Erasmus Cedernaes, Christopher Cedernaes, Lauri Lampola, and Jonathan Cedernaes. Published on May 28, 2023, in Obesity, it was funded by various institutions, including the Swedish Diabetes Foundation, the Forte – Swedish Research Council for Health, Working Life and Welfare, the Swedish Society for Medical Research (SSMF), Göran Gustafsson’s Foundation, and the Swedish Brain Foundation (Hjärnfonden).

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• Uppsala University
• Obesity Journal
• Swedish Diabetes Foundation
• Forte – Swedish Research Council for Health, Working Life and Welfare
• Swedish Society for Medical Research (SSMF)
• Göran Gustafsson’s Foundation
• Swedish Brain Foundation (Hjärnfonden)