Frozen pizza and beef buns can cause poor sleep.

15 young adults without sleep problems participated in the study in Uppsala. They were divided into two groups where, for a week, each group ate exactly the food the researchers had given instructions for. Participants were also given instructions about how much they were allowed to eat. The idea was for everyone to eat their fill.

Yogurt and salmon are on the menu

One group ate the following every day for a week: relatively low-fat yogurt and muesli for breakfast, pasta with green peas for lunch, and salmon pie for dinner.

The other group ate yogurt, fat and sweetened muesli for breakfast, pasta with ready-made meatballs and ketchup for lunch, and frozen pizza and a piece of sweet chocolate for dinner.

The idea was to measure whether food affected sleep in any way. Previous studies, conducted in other ways, have indicated that this may be the case.

Sleeping with electrodes placed on your head

To measure sleep during the week, participants wore activity monitors and wrote information about their sleep in a diary. In this way, the researchers knew, among other things, how much the participants slept.

But it was not possible to measure sleep quality and what the different stages of sleep look like in this way. So, after completing the food week, the participants had to spend two days in the sleep lab. There, they slept with electrodes on their heads so that researchers could measure the activity of their brains using an EEG.

Deep sleep was different

The result: Participants slept the same amount of time throughout the period, both at home and in the lab, regardless of what they ate. They also spent the same amount of time in different stages of sleep.

But deep sleep was different. Deep sleep was shallow in those who ate more junk food, such as frozen pizza, takeaway meatballs, and so on. It was also visible during the last day, when the participants finished their diets and started eating the same food.

Same with insomnia

Such changes in deep sleep can also be seen in people after a certain age and in those with sleep difficulties of the insomnia type, says Jonathan Cedernais, MD, Ph.D. and assistant professor of medical cell biology at Uppsala University.

– In such circumstances, in theory, from a sleep perspective, it might be more important to be careful with diet, he says.

It is not known exactly how food may affect it

Researchers don’t know if altered sleep quality, like the one in the study, affects functions in daily life. The researchers say it would be interesting to carry out tests that show, for example, whether memory functions can be affected. These functions are largely controlled by sleep.

– At least it would be interesting to understand how long the effect on sleep can last. Today, we also don’t know of any substances or any substances in an unhealthy diet that led to more shallow, deep sleep, says Jonathan Cedernaes.

He says there are several possible explanations.

Animal studies have shown that sugar can affect sleep. It can also be fatty particles that have an effect. Or maybe fiber, which causes the formation of neurotransmitters in the intestines. We don’t know yet.

Is there an evolution-oriented explanatory model?

– What you can tell from this aspect is that our brains are not really made for the food we have today. We see it in different ways around the world, with different diseases affected by what we eat.

It was interesting to increase the sugar and fat content of “junk food” in the current study, says Jonathan Cedernais. Perhaps it could have been linked to more pronounced effects on sleep. But he thinks it’s still a good idea to study like I did.

– The idea was that the useless diet could be a diet that many in the community could eat every day. In a way, it reminds us of the poor man’s diet of many of the students, for example. Unfortunately, the most useful food is often the most expensive.

Text: Uppsala University and forskning.se

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Academic subject:

Exposure to an unhealthy diet affects the sleep microstructure during normal sleep and recovery sleep: a randomized trialAnd obesity.

communication:

Jonathan Cedernaes, MD and Associate Professor of Medical Cell Biology, Uppsala University
[email protected]