New findings from researchers at Uppsala University in Sweden show that what people eat may not change how long they sleep, but it does alter the characteristics of sleep. The results appeared in the journal Obesity, shedding light on how meals high in fat and sugar shape brain activity during rest.
In the study, a diet rich in fat and sugar was linked to a reduction in delta activity—a high amplitude slow brain rhythm visible on an electroencephalogram (EEG)—combined with higher levels of alpha and theta rhythms during deep sleep. These shifts indicate changes in the architecture of sleep that could influence its restorative properties, even when total sleep time remains the same.
The researchers stressed that short-term use of an unhealthy diet changes the fluctuating properties that govern how restorative sleep feels day to day. They cautioned that more work is needed to determine whether these sleep changes translate into the known health risks associated with poor dietary choices.
The experiment involved fifteen healthy men who were required to maintain between seven and nine hours of sleep each night, keep a sleep diary, and eat three meals daily. Participants were divided into two groups: one followed a diet considered healthy, low in fat and sugar; the other followed an unhealthy, high-fat, high-sugar plan. EEG data were collected from the participants during sleep, providing a detailed look at how the two dietary patterns interact with brain activity across the night.
These findings point to a nuanced relationship between diet and sleep. While total sleep duration might not shift significantly in the short term, the composition of sleep stages and brainwave activity can change in meaningful ways. Such differences could influence how refreshed someone feels upon waking and how well the body recovers during sleep. The study adds to a growing body of evidence that diet quality can subtly influence brain function during rest, which in turn may affect daytime performance, mood, and metabolic health over time.
Overall, the Uppsala study suggests that dietary choices matter for the quality of sleep at the neural level. The practical takeaway for individuals aiming to optimize sleep might be to prioritize meals with balanced macronutrients and lower saturated fat and added sugars, especially in the hours leading up to bedtime. In the end, the researchers emphasize the need for broader investigations to determine long-term health implications and to explore how these sleep changes interact with exercise, stress, and other lifestyle factors. This ongoing inquiry sits at the intersection of nutrition science and sleep research, promising a more complete picture of how daily habits shape nightly rest and daytime well-being.
Attribution: Uppsala University, findings reported in Obesity.