High-fat, high-sugar diets impact quality of deep sleep, study finds
- A study by scientists from Uppsala University investigated the impact of a high-fat, high-sugar diet, also known as a junk food diet, on sleep.
- The researchers found that after consuming the unhealthy diet, participants’ deep sleep quality deteriorated compared to when they were on the healthier diet.
- Although sleep duration and overall sleep structure were not significantly different between the two regimes, unhealthy diet was associated with reduced quality of deep sleep and changes in some important sleep patterns.
There is limited evidence regarding the influence of certain foods on sleep, which led researchers to conduct a randomized trial investigating the effects of a high-fat, high-sugar diet on sleep.
A new study published in Obesityaimed to gather intervention-based evidence by examining the impact of this diet on sleep patterns in healthy individuals.

The researchers found that after consuming an unhealthy diet, participants’ deep sleep quality deteriorated compared to when they were on a healthier diet.
A group of 15 healthy men participated in a study where they were given two different diets to follow. They were randomly assigned to a high-fat, high-sugar diet or a low-fat, low-sugar diet for one week each.

After each diet, the researchers recorded the participants’ sleep patterns in a lab using a method called polysomnography, a technique for monitoring sleep.
They looked at sleep duration, as well as different stages and patterns of sleep, including things like oscillatory patterns and slow waves.
The study found that sleep duration was not significantly different between the two regimens, as measured by actigraphy – a method of monitoring sleep using a wearable device – and polysomnography in the laboratory. .
By comparing two different diets, the researchers found that sleep patterns remained similar after a week on each diet.
However, when they compared a diet high in fat and sugar with a diet low in fat and sugar, they found that the former diet was linked to lower levels of certain sleep characteristics during deep sleep.
These characteristics included delta power, which is a measure of slow brain waves, the ratio of delta waves to beta waves, and slow wave amplitude.
All of these changes suggested that the quality of deep sleep was reduced with the high-fat, high-sugar diet.
Dr. Florencia Halperinchief medical officer of Form, a company that provides medical treatments for obesity and related metabolic disorders, not involved in this research, said Medical News Today that “evidence has accumulated over the past decade on the relationship between sleep and metabolic disease”.
“Poor sleep negatively affects hormonal and metabolic parameters and increases the risk of weight gain and metabolic diseases. At the same time, weight gain increases the risk of sleep disorders such as sleep apnea. So the relationship is very complex and there are so many things that we still don’t understand.
– Dr. Florencia Halperin
Dr Halperin pointed out that “the findings suggest that consuming an unhealthy (high fat/high sugar) diet leads to changes in sleep patterns”.
“Although the macro-architecture was unaffected, the observed changes in some sleep parameters (less relative power in delta frequencies and a lower delta-to-beta ratio) were consistent with a less restful sleep state, as might be seen in an older population,” Dr. Halperin noted.
Kristen Carlia registered dietitian nutritionist, also not involved in this research, pointed out some limitations to the study, noting the small sample size of just 15 healthy young men.
“No women, elderly people or children were evaluated, which means that these results should not be extrapolated to the general population,” Carli stressed.
Dr Halperin agreed, saying that “we need to bear in mind that only 15 people were studied, they were all male, and only studied for 1 week – so we will need further research to validate these results”.
However, Dr. Halperin noted that “this study is important and relevant for patients and the public because it provides new insight into how lifestyle factors such as the diet we eat affect our sleep, which in turn affects our overall health.”
“This is early evidence that a typical unhealthy diet can affect our sleep in very specific ways, and therefore our sleep-regulated health parameters, such as cognition and hormone secretion, which then modulate further. other effects on our health.
– Dr. Florencia Halperin
Dr. Halperin explained that while the study helps raise public awareness of the relationship between sleep and overall health, the current findings are unlikely to have an impact on medical practice at this time, given the early nature of this research.
However, “I can share this research with (my patients) to educate them on the many ways changing our diet can help improve health – even without any weight loss!” said Dr. Halperin.
Carli pointed out that “the implications of this study are that the high-fat, high-sugar diet may impact sleep quality.”
“Although the results of this single study should not be widely extrapolated, these results are not really surprising,” she added.
“Sugar has been shown to impact sleep quality in previous researchand a high in fat diet. However, I will note that many researchers question whether diet has an impact on sleep quality or the other way around. Anyway, as a dietitian, there are many other health benefits besides sleep quality to consider choosing a low-fat, low-sugar diet, including weight loss, heart health , chronic disease prevention, etc.
–Kristin Carli
Ultimately, as Dr. Halperin explained, “this evidence suggests that eating healthier foods may help us get healthier sleep.”
“Another way of looking at it is that maybe this is more proof that our parents were right after all – we all need to eat our vegetables and go to bed on time!”