Sleep deprivation and circadian rhythm affect public health

Woman sleeping.

Our data indicates that the quality of sleep are impaired when participants eat an unhealthier diet compared to a more healthy one, explains Jonathan Cedernaes, physician and sleep researcher. Photo: Getty Images

A large proportion of today’s population, both adults and children, are not getting enough sleep. Many people also work shifts, which disrupts our circadian rhythms. Jonathan Cedernaes, researcher at Uppsala University, studies how sleep interacts with important lifestyle factors, such as diet and physical exercise.

Previous research has shown that disrupted sleep and circadian rhythms increase the risk of a number of public health diseases, such as obesity and type 2 diabetes.

“In my research, I have focused on advanced clinical studies where we can isolate the effect of changing individual factors," explains Cedernaes. “For example, by keeping participants awake for an entire night or for half the night, we can examine the effect of sleep deprivation itself. My focus is then on what happens at the biomarker and tissue level, with the aim of finding new ways to treat diseases such as diabetes.”

Unique research involving many waking nights

Cedernaes received the Göran Gustafsson Grand Prize in 2019 for his three years of research into how different lifestyle factors interact with disturbed sleep and our circadian rhythms, with a focus on diet and exercise. The research project studied how a more ‘unhealthy’ diet can impact on important aspects of health. The researchers also investigated how too little sleep can in turn influence how physical exercise affects our metabolism and various biomarkers that are important for regulating our metabolism, as well as the risk of cardiovascular disease.

"It has been very exciting to conduct this research, which involved many waking nights and many hours with all the participants we have had in our sleep labs," notes Cedernaes. “In addition to keeping participants awake for different lengths of time, we also took samples at all hours of the day to build a comprehensive picture of how circadian rhythms are affected.”

Unhealthy diet can reduce quality of sleep

One of the areas Cedernaes has been interested in is how an unhealthy diet can increase the risk of public health diseases through its impact on our sleep and crucial circadian rhythms.

“We have data which indicates that neurobiological parameters reflecting the quality of sleep are impaired when those same healthy participants eat an unhealthier diet compared to a more healthy one,” explains Cedernaes. “This is despite the fact that on each occasion they ate the same amount of calories, at the same time of day, and slept for the same amount of time.

These sleep-quality parameters – which appear to be impaired by an unhealthy diet – are important for factors such as hormone secretion, cognition and blood sugar metabolism.

“What’s interesting in this context is that our data also suggests these changes may persist for some time after discontinuing the less healthy diet. It will therefore be interesting to follow up on these findings to see if the impact of diet on sleep can help us explain how an unhealthier diet can impair our metabolism, among other aspects.”

Several analyses are also under way where metabolism is studied in more detail, based on both molecular and genetic changes such as diet and exercise in interaction with sleep and circadian rhythms.

Too little sleep risks impairing metabolism

Cedernaes wants to help establish greater understanding of how the interaction between different lifestyle factors affects public health, based on sleep and circadian rhythms. An important part of this is highlighting the significance of our circadian rhythms.

“There are many mechanistic studies on this using animals, but we lack an understanding of its significance and mechanisms in humans,” continues Cedernaes. “We also hope we will be able to pinpoint biomarkers that can be used to identify those at higher risk of metabolic disorders, for example. This applies to those who do not sleep enough over the long term, or those who have to work shifts for long periods, as two examples. Our aim is to focus on patients with type 2 diabetes in order to understand the specific role of lifestyle factors in relation to sleep and circadian rhythms in this important group of patients.

Sleep is a valued topic among the general public, and it is hoped that future research will also make people and funding bodies aware of the importance of normal circadian rhythms for both public health and a variety of disease processes.

“Circadian rhythms are present in every cell of the body and are crucial for a normal metabolism,” notes Cedernaes. A growing body of data also suggests that normal circadian rhythms are a strong predictor of mortality, including due to cardiovascular disease, and that they regulate important ageing processes. It is therefore very important that we in Sweden are also able to invest more in attempts to become a leader in this field of research.

Tailor diagnosis and treatment

The highly controlled clinical studies are uniquely important, with their carefully controlled study protocols involving participants in the sleep laboratories. These enable a better understanding of mechanisms that regulate important aspects of metabolism and are relevant to disease evolution.

“I hope that in future we will be able to tailor diagnosis and treatment based on factors identified in our studies. We know that sleep and circadian rhythms affect a wide range of physiological processes, such as crucial aspects of the metabolism. There is therefore great potential to improve clinically relevant aspects based on the findings of our studies, together with the findings of other researchers in our field,” concludes Cedernaes.

Cecilia Yates

Subscribe to the Uppsala University newsletter