Sleep disorders are on the rise. Research published in the Journal of Clinical Sleep Medicine found that an estimated 13.6 million U.S. adults suffer from at least one sleep disorder. This figure doesn’t even include the tens of millions who experience occasional sleep issues, such as trouble falling asleep or staying asleep.
Fortunately, one straightforward way to support better sleep is to reduce or eliminate processed and high-sugar foods. Multiple epidemiological studies have shown that diets high in sugar and refined foods are linked to lower sleep quality and more sleep disturbances.
Now, a recent study from Uppsala University in Sweden has added to this growing body of evidence. The researchers found that cutting out junk food can significantly improve REM sleep—the restorative, dream-heavy stage that plays a crucial role in memory, healing, and mood regulation.
Study Overview: How Diet Impacts REM Sleep
Though the study was small—with just 15 participants—it was a randomized cross-over trial, meeting the international standard for scientific trials.
Researchers recruited healthy, normal-weight young adults with regular sleep habits, typically sleeping between seven and nine hours per night. Participants were asked to follow two diets in random order: one healthy and one unhealthy, with a washout period in between. Both diets were carefully calibrated to meet each person’s daily caloric needs.
The primary difference was in food quality. The “unhealthy” meals were high in added sugars and processed ingredients, while the “healthy” diet consisted of more whole foods. All participants consumed their meals at the same scheduled times each day, and both sleep and activity patterns were closely monitored.
After each diet period, participants underwent sleep monitoring in a laboratory. First, they were allowed to sleep a normal night with brain activity measured. Then, they were kept awake for a period before being allowed to catch up on sleep. Both sleep sessions were carefully tracked and analyzed.
Junk Food Leads to Shallower REM Sleep
At the end of the two test phases, the results were clear. When participants consumed the unhealthy, high-sugar diet, the depth and quality of their REM sleep suffered significantly.
“Specifically, we looked at slow-wave activity, a measure that can reflect how restorative deep sleep is,” said Dr. Jonathan Cedernaes, physician and associate professor at Uppsala University. “Intriguingly, we saw that deep sleep exhibited less slow-wave activity when the participants had eaten junk food, compared with consumption of healthier food. This effect also lasted into a second night, once we had switched the participants to an identical diet.”
In other words, poor food choices not only disrupted sleep on the day of consumption, but continued to affect REM sleep quality even after the diet was improved. That’s a powerful finding for anyone looking to improve sleep naturally.
“Essentially, the unhealthy diet resulted in shallower deep sleep,” Cedernaes added. “Of note, similar changes in sleep occur with aging and in conditions such as insomnia. It can be hypothesized, from a sleep perspective, that greater importance should potentially be attached to diet in such conditions.”
REM Sleep Is Crucial for Recovery and Brain Function
While total sleep duration remained consistent between both diet periods, the difference in REM sleep quality was striking. This matters because REM sleep is when the brain processes emotions, consolidates memories, and supports immune repair.
A lack of quality REM sleep has been linked to anxiety, depression, cognitive decline, and weakened immune response. Even a subtle reduction in REM sleep over time can result in chronic fatigue and mood disturbances.
Study Limitations and Areas for Further Research
Due to the small sample size, the researchers caution against drawing overly broad conclusions. Still, the implications are compelling and worth investigating further.
Among the researchers’ next goals is to identify which specific nutrients or food additives are most responsible for the decline in sleep quality. For instance, there is ongoing debate around whether saturated fat plays a negative role in sleep health. More targeted studies could help clarify that link.
“It would be interesting to investigate whether there is a particular molecular factor that plays a greater role,” the authors wrote. “Our dietary intervention was also quite short, and both the sugar and fat content could have been higher. It is possible that an even unhealthier diet would have had more pronounced effects on sleep.”
The study was published in Obesity in May 2023.
Nutrients That Naturally Support Sleep Quality
While eliminating junk food is an excellent first step, incorporating sleep-supportive nutrients can also make a big difference. Here are some of the most studied and trusted options:
- Valerian Root
Used since ancient Greece and Rome, valerian is one of the most well-researched herbal sleep aids. It helps calm the nervous system and reduce nighttime awakenings. - L-Tryptophan
This essential amino acid must be obtained through diet and is known for its calming effects. It serves as a precursor to serotonin and melatonin, which regulate mood and sleep. - Chamomile Flower
Chamomile contains apigenin, an antioxidant that binds to receptors in the brain to help reduce anxiety and promote sleep onset. - Lemon Balm
With historical roots dating back more than 2,000 years, lemon balm has been shown to support GABA activity in the brain, helping to calm the mind and prepare the body for rest. - Hops Extract
Known as a key ingredient in beer, hops have long been used medicinally for their sedative effects. Modern studies confirm their role in reducing sleep latency and promoting sleep depth.
Incorporating these ingredients through teas, supplements, or sleep blends may help counteract occasional insomnia or disrupted sleep cycles—especially when paired with a healthy diet.
Final Thoughts
Sleep is not just about the number of hours spent in bed— it’s also about quality. And based on this new research from Uppsala University, the quality of what you eat may directly influence the quality of your sleep.
Cutting back on processed, sugary foods is an actionable step you can take today to improve your REM sleep and overall well-being. Combine it with nutrients known to support relaxation, and you could begin to see noticeable improvements in mood, energy, and cognitive function.
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