A new study from Uppsala University shows that people who ate a diet rich in fat and sugar had impaired deep sleep similar to the sleep problems that come with old age or insomnia.
A group of 15 young and healthy men had to alternately eat junk food for one week, and then healthy food for one week.
In a sleep laboratory, the sleep of the participants was then monitored in detail.
Better recovery
It turned out that the participants slept for the same amount of time regardless of diet – but those who ate a healthier diet had better quality of deep sleep. Good quality deep sleep is associated with better recovery, and is exactly the type of sleep that declines with age or insomnia.
– We were particularly interested in investigating what the quality of deep sleep looked like, as it can be a measure of how restorative the sleep is. Interestingly, we saw that the deep sleep was shallower when the participants had eaten unhealthy food, compared to after the more healthy food, says Jonathan Cedernaes, doctor and associate professor in medical cell biology at Uppsala University.
Unhealthy = saturated fat and sugar
In the study, the unhealthy diet is counted as rich in both saturated fat and sugar, while the healthy diet is rich in fiber and contains a smaller proportion of fat and sugar. The participants received the same amount of calories regardless of diet in the study.
– Both poor diet and poor sleep can increase the risk of several public health diseases. As diet is so important for health, we wanted to find out if some of the health effects of diet include changes in our sleep, says Jonathan Cedernaes, who was involved in constructing the study.