A recent study conducted at Uppsala University in Sweden suggests that a diet high in sugar and fat can lead to disrupted sleep quality. The study involved 15 men who were randomly assigned a high-fat, high-sugar diet or a low-fat, low-sugar diet for one week. They then slept in a laboratory wearing an electroencephalography (EEG) cap to record their brain activity. The results showed that the high-fat, high-sugar diet disrupted slow-wave sleep by reducing the proportion of delta waves and increasing beta waves, suggesting that it was less restful. While the participants slept for the same length of time on both diets and felt their sleep quality was the same, the EEG recordings revealed otherwise.
The study suggests that sugar and fat activate brain pathways that increase how awake people feel, which could explain the disrupted sleep quality. However, more research is needed to understand the mechanisms behind this effect. The long-term impact of disrupted slow-wave sleep is still unknown, but poor diets are known to lead to worse health, which could be partly explained by their impact on sleep quality.
The amount of slow-wave sleep that we naturally get declines with age, making a healthy diet particularly important in older age to protect against further losses in sleep quality. While the study only involved men, the researchers hope to repeat it with women to see if the results are similar.
Overall, the study highlights the importance of a healthy diet in maintaining good sleep quality. It also raises questions about the potential impacts of our modern Western-style diets, which are often high in sugar and fat.