New Study Reveals: Junk Food Takes a Toll on Deep Sleep Quality

June 5th, 2023

By Amelia Harris

Staff Writer for Wake Up World

A groundbreaking study conducted by researchers at Uppsala University sheds light on the relationship between junk food consumption and sleep quality. The study, which explored the effects of healthier and unhealthier diets on sleep, revealed a significant deterioration in deep sleep quality after consuming an unhealthy diet. These findings highlight the interplay between diet and sleep, underscoring the importance of maintaining healthy eating habits for optimal sleep and overall well-being. The study’s results have been published in the journal Obesity.

The Influence of Diet on Sleep: While numerous epidemiological studies have established a link between diet and sleep patterns, few have directly investigated how diet impacts sleep quality. To address this gap, the researchers designed an intervention study where participants followed different diets in a randomized order. This approach allowed them to isolate the mechanistic effects of various diets on sleep.

Jonathan Cedernaes, an Associate Professor in Medical Cell Biology at Uppsala University, emphasizes the importance of both diet and sleep for overall health:

Both poor diet and poor sleep increase the risk of several public health conditions. As what we eat is so important for our health, we thought it would be interesting to investigate whether some of the health effects of different diets could involve changes to our sleep.

The Impact on Deep Sleep

Deep sleep plays a crucial role in hormonal regulation and overall restoration. The study’s focus was to assess how an unhealthy diet affects deep sleep quality compared to a healthier diet. The results revealed that participants experienced a significant reduction in slow-wave activity—a measure of restorative deep sleep—after consuming junk food compared to a healthier diet. Interestingly, this effect persisted even after participants switched to the healthier diet, indicating a lingering impact on deep sleep. These changes in sleep quality resembled those observed in conditions such as insomnia and aging, highlighting the potential significance of diet in these contexts.


The Study Design

The study involved 15 healthy young men of normal weight who participated in two sessions. The participants followed both a healthier diet and an unhealthier diet in random order, with each diet providing the same number of calories tailored to individual requirements. The unhealthier diet consisted of higher sugar and saturated fat content, as well as more processed food items. Sleep, activity, and meal schedules were closely monitored throughout each diet session.

The Future Implications

While this study provided valuable insights into the relationship between junk food and sleep quality, several questions remain unanswered. The researchers did not assess the long-term effects of the unhealthy diet on sleep or investigate whether the shallower deep sleep observed could impact other functions tied to deep sleep, such as memory. Additionally, the study’s duration and diet composition could be further explored to uncover more pronounced effects.

Cedernaes acknowledges these gaps and suggests future directions: “It would also be interesting to conduct functional tests, for example, to see whether memory function can be affected. This is regulated to a large extent by sleep. And it would be equally interesting to understand how long-lasting the observed effects may be.”


The Uppsala University study illuminates the connection between junk food consumption and sleep quality, emphasizing the importance of maintaining a healthy diet for sound sleep. The findings provide a wake-up call to the potential consequences of an unhealthy diet on deep sleep, a crucial phase of restorative sleep. As further research is conducted in this area, it is crucial to recognize the interdependence of diet and sleep and prioritize healthy eating habits to promote overall well-being and enhance the quality of our rest.


About the author:

Amelia Harris is a writer and eco-activist, interested in health and all things esoteric, with a passion for sharing good news and inspiring stories. She is a staff writer for Wake Up World.

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