Study: Unhealthy diet can interfere with deep sleep

An unhealthy diet can adversely affect deep sleep, according to new Swedish research. However, more research is needed to determine how long the effects last and what in the diet affects sleep.

The food you eat affects most aspects of your health, and it’s not just about nutrition. For example, a recent study showed that fried foods may increase anxiety. It also affects our sleep, although there are not too many studies on this subject. In contrast, one study, for example, has shown that low carbohydrate intake in general may be associated with poor sleep, while another study suggests that a high GI diet may also have a negative impact on sleep.

In a new study, researchers at Uppsala University investigated how unhealthy food affects sleep. The study involved 15 healthy, normal-weight men who usually slept normally, seven to nine hours a night. Some of the participants were randomly assigned to eat a healthier diet and some to eat a less healthy diet, both of which contained the same amount of calories, but the amount of calories was calculated individually. The diets were followed for a week while the participants’ sleep, activity, and adherence to the diet were monitored. At the end of the week, the men were observed in a sleep lab.

In the sleep lab, they first slept normally for one night while brain activity was measured. They were then kept awake before being allowed to catch up on the sleep they had missed.

The results show that both groups slept the same amount of time and spent the same amount of time in the different stages of sleep. However, the participants who ate a more unhealthy diet had more shallow deep sleep.

– We were particularly interested in looking at the quality of deep sleep because it can be a measure of how restorative sleep is. Interestingly, we found that deep sleep was shallower after the participants ate the unhealthy food compared to the healthier food. This effect also persisted on a second night, after the participants had finished their respective diets and instead ate an identical diet, said Jonathan Cedernaes, MD and Associate Professor of Medical Cell Biology at Uppsala University, in a press release.

However, it is not clear how long the negative effects of an unhealthy diet last, nor is it known whether the change in sleep quality affects functions such as deep sleep. It is also not known what it is about the unhealthy diet that affects deep sleep. Cedernaes believes that more research is needed in this area.

– It would be interesting to investigate further whether any particular factor contributes more. Our dietary intervention was quite short, and both the sugar and fat content could have been higher. It is possible that an even more unhealthy diet would have had more pronounced effects on sleep, says Cedernaes.