News: Three questions for Laura Lewis: The importance of sleep

Laura Lewis, a core faculty member at IMES, describes how her research focus came to encompass developing methods to analyze neuroimaging data, and why she has a particular interest in applying these methods to the study of sleep, and its importance for a healthy brain.

Mindy Blodgett | IMES/HST

We know that sleep is valuable and necessary for good human health—but there are still some mysteries around it, and why our bodies and minds suffer when we don’t get enough of it. Laura D. Lewis, the Athinoula A. Martinos Associate Professor of the Institute for Medical Engineering and Science (IMES), and the Department of Electrical Engineering and Computer Science (EECS), has dedicated her research to uncovering why sleep is so important for a healthy, functioning brain. Lewis, who received her PhD in Neuroscience from MIT— training with Emery N. Brown, the Edward Hood Taplin Professor of Medical Engineering and of Computational Neuroscience, MIT, and a core faculty member at IMES—came to MIT from Boston University in early 2023. Currently, space at Building E25, where IMES is based, is being renovated to create the first sleep lab at MIT—one that can work with human subjects, so that Lewis and her colleagues can better research sleep and its effects on physiology. Lewis will be focusing in particular on neurotechnologies for sleep.

Q: Your research focuses on multimodal approaches for imaging the human brain, and applies them to studying the neural circuitry that controls sleep. Can you tell us more about your area of research? Why is it so important to better understand the consequences of sleep and its impact on brain function?

A: Sleep is essential for brain health. Even after a single night of sleep deprivation, we feel the negative consequences for our mood, attention, and cognition. On longer timescales, disrupted sleep is also linked to serious health consequences for the brain. I'm very interested in why sleep is so beneficial for the brain, and what controls sleep. Knowing this could help us make better diagnoses, and in the long term hopefully help us enhance sleep and treat disorders linked to poor sleep, such as Alzheimer's disease, insomnia, and depression.

A major focus of my research is on brain imaging technologies that can be used in humans, because I think this is critical in order to make progress in the neuroscience of sleep. Sleep changes activity throughout the whole brain, and also changes many other aspects of body function, like changing our breathing and heart rate, so to study it we need tools that let us measure many different aspects of the brain at the same time, with high precision.

Q: Can you tell us more about your interest in fast fMRI, EEG, and PET, and how to apply those methods to the study of sleep?

A: One area we've focused on is imaging the cerebrospinal fluid (CSF), which is the fluid that envelops the brain and helps clear waste out of the brain. We found a way to use fast fMRI to measure CSF flow in the brain while people are sleeping. Our new imaging tool enabled us discover that during sleep, large waves of CSF flow through the brain. This is an exciting result because it suggests that sleep could drive fluid flow in the brain, which would help explain why it has been linked to increased waste clearance.

We're also very interested in using fast fMRI to understand the brain circuits that control sleep. By imaging very quickly, we can now see cascades of brain activity that unfold over times. This method has helped us identify specific brain circuit patterns linked to specific aspects of sleep. For example, we recently found a sequence of brain activity that happens just before people wake up from sleep, which we think is an important mechanism for generating and sustaining wakefulness.

We integrate MRI tools with other methods such as EEG, to measure electrical activity in the brain, and PET, to measure levels of neuromodulators like dopamine. Using multiple techniques together is challenging but gives us a unique window into how different aspects of brain function work together in sleep. Sleep changes nearly everything about brain physiology, so considering a single component of the system at a time can miss important mechanisms. We use these new technical approaches to aim to understand how multiple brain systems work together to create sleep and wakefulness.

Q: Tell us a bit about your background and how it is that you became interested in the study of sleep and brain function? What are your goals for your research, and your career?

A: I became fascinated by the brain when I was an undergraduate student, after taking an introductory neuroscience class and being struck by the mystery of how the brain can generate such complex and rapidly evolving experiences. I did my Ph.D. in neuroscience focused on how general anesthesia affects the brain, and I became very interested in how the brain can rapidly switch between different states. Sleep is the quintessential example of this, as our brains flexibly change our experience of the world across sleep states. I decided to focus on sleep, but I realized that to make progress on this question, we needed better tools. I made a detour in my postdoc to focus on fMRI techniques, working to adapt fMRI technologies to measure new aspects of brain physiology in humans.

In my view, integrating tool development with neuroscience is needed to make progress on understanding the biology of sleep, as our methods are still a limiting factor in what we can study. I built an interdisciplinary lab aiming to solve this problem: we are engineers developing new techniques to understand brain physiology using noninvasive imaging in humans, and neuroscientists using these advanced methods to understand fundamental neurobiology of sleep. As part of this effort, I mentor students and postdocs, and one of my main goals is to provide a great training environment and help them launch their careers in research and engineering. I aim for our lab to create techniques that allow not just us, but the broader neuroscience community, to be able to extract rich new information from neuroimaging technologies. My long-term scientific goal is to understand the brain circuits that control sleep and wakefulness, and to identify what sleep is for, why it benefits the brain, and develop strategies to enhance sleep in neurological disorders.