Sleep is so much more than rest

We spend much of our lives sleeping. In fact, very young children sleep more than they are awake. Sleeping well is essential for our health and development. But little is known about it. Researchers in Utrecht are working hard to discover as much as possible about this everyday phenomenon. Their different backgrounds and disciplines make knowledge exchange and collaboration exciting. For what are the similarities between the disturbed sleep of a zebra finch and that of a premature baby? A conversation with three researchers.

Behavioural scientist and biologist Sita ter Haar (UU) studies sleep deprivation in zebra finches and speech development in babies: "How song development works in birds is a good model for humans. Sleep is important for learning. Of course, birds sleep differently from humans. But there are also similarities. If sleep is disturbed, it might affect song development in birds and language development in babies. Almost all animal species sleep and that has important functions. I find that interesting."

Almost all animal species sleep and that has important functions. I find that interesting.

Paediatrician/neonatologist Jeroen Dudink (UMC Utrecht) knows all about the importance of sleep in premature infants: "Babies are mainly concerned with sleep. That's pretty much their most important activity. Especially in that first phase of life, sleep has a distinct role for further development. With vulnerable children', such as premature babies, this applies even more. Then it is even more important to optimise sleep where possible. That's why I want to investigate how we can do that."

Professor/medical neurobiologist Freek Hoebeek (UMC Utrecht) is fascinated by brain development: "The cerebellum controls the rest of your brain. Research increasingly shows that cerebellar development influences behaviour and cognition. Active sleep, similar to REM sleep in adults, plays an important role in this. What if a premature baby does not get enough active sleep? What long-term effects does that have on brain development, cognitive skills and behaviour? These questions keep me busy."

Everyday and essential phenomenon

What fascinates these Utrecht researchers about sleep? Jeroen: "It is extraordinary that we pay so much attention to what happens during the day and are less concerned with the night. Sleep is so much more than resting and is mainly about recovery and growth. Your brain is actually very active when you sleep."

Freek adds: "You need sleep for your brain to grow and make certain connections. In small children, brain areas still need to grow together. Research shows that the impact of disrupting sleep is much greater than we knew until now. For example, there are critical moments to learn something. At a later time, your brain may find it harder or even impossible to get that done." Sita: "Sleep is so important. During sleep, we process the information we learn during the day."

The impact of disrupting sleep is much greater than we knew until now

Sharing knowledge, education and research

Jeroen: "During my studies, I was already gripped by the impact of sleep on health and development. But little attention is paid to it in medical education. There is a lot of knowledge, but it could be shared much more widely."

This spring, Utrecht University, the WKZ/UMC Utrecht and the Prinses Máxima Centrum joined forces and launched the Sleep Discovery Lab: a virtual platform dedicated to sleep research and innovation. Jeroen: "The Sleep Discovery Lab is mainly focused on visibility and meeting. Which researchers are working on sleep in animals, or in elite athletes or babies? How do you get in touch with each other? We also want everyone to be able to ask questions. What should scientists really investigate? We are now also getting in touch with other organisations to see how we can work together, for example with the Brain Foundation."

Fundamental research in animals

The researchers in Utrecht focus mainly on sleep physiology (how does sleep work?) rather than sleep disorders. In doing so, they do both fundamental research and practical studies. Freek: "We will soon start research into early life stress, led by neurobiologist Michael van der Kooij in collaboration with neonatologist Maria Luisa Tataranno. We are investigating this in rodents. Fundamental research in humans is more difficult. You have to exclude other influence factors and many measuring instruments, such as a wristwatch or headset, are not yet accurate enough. You can't consciously manipulate sleep in humans either. But we do want to investigate the impact of sleep deprivation. Can you recover from it? Is there a critical recovery period? Fundamental research in animals can teach us more about this."

The study in zebra finches shows that the group of birds with sleep deprivation ended up learning to sing less well than the control group. Sita: "These songbirds do recover, once they get more undisturbed sleep again. The question, of course, is whether this also applies to humans and, in particular, premature babies."

Sleep diary

The researchers also take a practical approach. For example, a sleep diary has been developed in collaboration with the Kempenhaeghe sleep centre. Jeroen: "For example, we ask parents and - if possible - children themselves to keep track of how they sleep. This shows a strong link between stress and sleep. It also turns out that if one person in the family sleeps badly, this affects the rest of the family. You can also imagine that illness or a premature child has an impact and causes stress. But it has now also been increasingly shown that it carries on in a family. Moreover, the sleep diary has also been shown to give parents insight."

Interventions and empowerment

Are there any new interventions or treatments as a result of the insights about sleep? In the neonatology department, they do consciously work on this. The researchers think that there is still much that can be done to optimise the sleep of these vulnerable babies. Freek: "Babies move a lot during their active sleep. As a result, parents and nurses cannot always see whether they are awake. If you then perform a medical procedure, for example, it disrupts that. If we can better monitor which stage of sleep the baby is in, we can tune in accordingly. Better equipment is becoming available for this."

Jeroen: "Thanks to digital developments, more and more is possible. For example, together with the Digital Health department, we have developed software that can display sleep stages from a patient's monitor data. So we have turned the patient monitor into a kind of smartwatch. That indicates pretty accurately whether the baby is asleep and at what stage. As a next step, we want to do an intervention study in the future. What is the long-term effect if we can better tailor the treatment to the sleep stage?"

Slowly the realisation that sleep has a major impact on our health is dawning on us. Jeroen: " Top athletes these days often have sleep coaches. The rehabilitation researchers we work with also see rehabilitation as a kind of top sport, so it is very important that we also help children who are rehabilitating to sleep optimally. Transferring knowledge about this to nurses and parents certainly helps, I am convinced. I hope we will become the most sleep-friendly hospital in the world in the future."

I hope we will become the most sleep-friendly hospital in the world in the future.