Mental Illness

Professor Yuan Chang Leong, a distinguished recipient of the 2026 APS Spence Award and an assistant professor at the University of Chicago, is at the forefront of neuroscience research. Leading the Computational Affective and Social Neuroscience Laboratory, his groundbreaking work focuses on deciphering how our emotions and social interactions sculpt our subjective experiences. Leong's interdisciplinary approach, integrating cognitive neuroscience and computational modeling, offers profound insights into how individual desires, goals, and fears influence our perception of the world and the intricate processes by which our brains construct reality. His research endeavors not only aim to understand these complex mechanisms but also aspire to foster conditions that promote well-being and adaptive behavior.

Leong's fascination with the subjective nature of perception was ignited by Akira Kurosawa's classic film 'Rashomon,' which vividly illustrates how personal motives color different accounts of the same event. This cinematic exploration of varied perspectives mirrors Leong's scientific inquiry: how do individuals, observing the same reality, arrive at distinct interpretations and conclusions? He recognized that our responses to the world are as revealing of our inner selves as they are of external stimuli. This realization propelled him to leverage tools from cognitive neuroscience and computational modeling, allowing researchers to peer into the 'mind of the beholder' and study human perception in dynamic, everyday contexts, from watching films to engaging in social interactions.

Among the significant discoveries from Leong's laboratory is the concept of 'motivated seeing.' Challenging the long-standing debate in psychology about whether desire influences perception or merely reporting, his team utilized neuroimaging to demonstrate that motivation directly strengthens neural representations corresponding to desired interpretations of ambiguous images. This finding reveals that our brain's encoding of the visual environment is not purely objective but is actively shaped by our internal states. Further extending this work, Leong explored 'neural polarization' in political contexts, observing that individuals with opposing political views exhibit divergent neural responses to identical news content. This phenomenon, he posits, stems from differing semantic interpretations of language, where seemingly neutral phrases carry distinct meanings across the political spectrum. More recently, his lab has uncovered how emotional moments in narratives lead to increased cohesion across brain networks, enhancing memory formation and illustrating emotion's role in coordinating brain systems during unfolding experiences.

The journey through an interdisciplinary field, while exhilarating, presents its own set of hurdles. Leong's work, straddling social and affective neuroscience, cognitive neuroscience, and social psychology, demands a fluency across diverse intellectual traditions. Each discipline, with its unique terminology, foundational assumptions, evidentiary standards, and scholarly community, requires a nuanced approach to communication and collaboration. Mastering the art of 'code-switching' to convey complex ideas effectively across these boundaries and actively participating in multiple intellectual communities remains a continuous learning process for him.

Looking ahead, Leong is committed to exploring more naturalistic research environments. His lab is embracing functional near-infrared spectroscopy (fNIRS), a mobile and cost-effective neuroimaging technique that allows for the simultaneous scanning of multiple individuals as they naturally interact. This innovative approach facilitates the study of how emotions, goals, and social dynamics unfold in real-time, such as during conversations between romantic partners, moving beyond the constraints of traditional fMRI methods. Leong emphasizes the importance of continuous learning, seeking out diverse ideas through consistent reading, conference attendance, and engaging in seminar series. He also stresses the invaluable role of mentorship and collaboration in scientific pursuit, acknowledging that supportive relationships not only impart methods but also broaden perspectives, refine critical thinking, and transform science into a shared intellectual endeavor. He expresses profound gratitude for the Janet Taylor Spence Award, viewing it not just as a personal accolade but as a testament to the collective efforts of his mentors, collaborators, and dedicated lab members.

Unlock the Hidden Power of Sleep: Transform Your Metabolism and Well-being!

Understanding the Active Role of Sleep in Bodily Regulation

Many individuals perceive sleep as a necessary downtime, a period when the body simply rests. This perspective often leads to prioritizing other activities over adequate rest, such as extended work hours, late-night entertainment, or personal pursuits. The common belief is that the primary consequence of reduced sleep is merely feeling tired the following day. However, emerging scientific evidence challenges this simplistic view, revealing that sleep is a dynamic and essential biological process that actively governs critical physiological functions, including hormone balance, metabolic rate, physical recovery, and even the level of physical activity we engage in during our waking hours.

New Insights: How Minor Sleep Loss Influences Weight and Sedentary Behavior

Two recent studies have significantly advanced our understanding of sleep's impact beyond just alertness. One study pinpointed a specific brain circuit responsible for linking sleep with the release of growth hormone, a crucial regulator of various bodily processes. The other, a more practical human study, demonstrated that even a modest reduction of approximately 80 minutes of sleep per night, sustained over six weeks, was associated with noticeable weight gain and an increase in sedentary behavior. These findings collectively suggest that consistently curtailing sleep can subtly push the body towards a state of compromised metabolic health, even when the sleep deficit seems minor and not immediately debilitating.

The Brain's Role During Sleep: Growth Hormone and Its Feedback Loop

Growth hormone (GH) is widely recognized for its importance in childhood development and athletic performance. However, its significance extends throughout adulthood, where it plays a vital role in tissue repair, maintaining muscle and bone mass, regulating fat metabolism, and controlling glucose levels. The close relationship between GH secretion and sleep, particularly deep non-REM sleep, has been long established. What has remained less clear until recently is the precise neural mechanism by which the brain orchestrates this relationship. A groundbreaking study published in Cell investigated neurons in the hypothalamus, a brain region pivotal for sleep, appetite, body temperature, and hormone regulation. Researchers identified complex interactions between neurons that release growth hormone-releasing hormone (GHRH) and those that produce somatostatin, an inhibitor of GH secretion. Interestingly, GH itself was found to provide feedback to the brain, influencing activity in the locus coeruleus, a brainstem area involved in wakefulness, attention, and arousal. This indicates a reciprocal relationship: sleep stimulates GH release, and GH, in turn, may help regulate the brain's transition back to wakefulness. This intricate feedback loop provides a biological explanation for the common experience that poor sleep not only induces drowsiness but also leaves individuals feeling physically drained, mentally sluggish, and inadequately revitalized.

Observing the Consequences of Reduced Sleep in Humans

A second comprehensive study focused on the effects of moderate sleep restriction in humans. Researchers analyzed data from randomized crossover trials involving 95 adults who typically slept for about seven to eight hours nightly. Participants underwent two six-week periods: one with their usual sleep patterns and another where their bedtime was delayed by 90 minutes, while their wake-up time remained constant. The average sleep reduction during the latter period was approximately 80 minutes per night, a scenario far more reflective of typical sleep loss than extreme sleep deprivation studies. Following six weeks of this reduced sleep schedule, participants gained an average of about one pound and spent an additional 17 minutes per day in sedentary activities. Although the weight gain of one pound may seem insignificant, and the study's scope was limited to a relatively small number of participants over a short duration, its implications are noteworthy. The sleep restriction was modest and mimicked common behaviors, such as going to bed later while maintaining a consistent wake-up time, a routine many individuals follow inadvertently. The study also hinted at potential subgroup differences, with men and postmenopausal women showing a greater increase in sedentary time, though further research is needed to confirm these findings definitively.

The Link Between Sleep Deprivation and Reduced Physical Activity

Discussions regarding sleep and body weight frequently center on appetite regulation. Insufficient sleep is known to disrupt appetite-controlling hormones, impact food choices, impair impulse control, and heighten the desirability of high-calorie foods. However, the human study points to an additional, often overlooked pathway: when individuals sleep less, they tend to move less. The observation that being awake for more hours does not equate to increased physical activity is significant. Even after accounting for the extended waking period, participants in the sleep-restricted group exhibited more sedentary behavior. This aligns with intuitive understanding: a fatigued person is more likely to skip exercise, take fewer steps throughout the day, remain seated during breaks, or simply lack the energy for routine movements that typically occur without conscious thought. Therefore, sleep loss may influence metabolism through a combination of subtle, interconnected mechanisms: reduced restorative hormonal activity, increased fatigue, greater sedentary behavior, alterations in appetite, less healthy food choices, and impaired glucose regulation. While none of these individual changes may be dramatic, their cumulative effect over weeks or months can be substantial, contributing to long-term metabolic health issues.

Sleep as a Pillar of Metabolic Health, Not a Quick Fix for Weight Loss

It is crucial to avoid oversimplifying these findings into the message that merely increasing sleep guarantees weight loss. Body weight is a complex interplay of numerous factors, including genetics, medications, medical and psychiatric conditions, stress levels, physical activity, access to nutritious food, and socioeconomic circumstances. For many individuals, simply deciding to go to bed earlier is not a feasible option due to challenges such as shift work, caregiving responsibilities, insomnia, chronic pain, sleep apnea, anxiety, depression, or mania. For these individuals, advice to "prioritize sleep" can be unrealistic and even frustrating. Furthermore, the research does not definitively prove that extending sleep will reverse weight gain. The human study investigated the effects of sleep restriction in individuals who typically had adequate sleep, rather than testing sleep extension as a treatment for obesity. The more accurate and reasonable conclusion is that sleep, alongside nutrition and physical activity, should be recognized as a fundamental component of metabolic health. It does not replace these other elements but rather establishes the biological environment in which they function optimally.

Cultivating Healthy Sleep Habits Without Added Stress

A practical first step toward improving sleep is to identify the root causes of sleep loss. Questions to consider include whether bedtime is gradually shifting later, if work demands are extending into the evening, whether late-night screen use is delaying sleep onset, or if substances like alcohol or caffeine, medications, chronic pain, mood disturbances, or breathing problems are interfering with sleep quality. Implementing simple, consistent habits can be beneficial: maintaining a regular wake-up time, ensuring the bedroom is dark and cool, reducing exposure to bright light in the evenings, and establishing a brief wind-down routine before bed. Persistent insomnia, loud snoring, gasping during sleep, severe daytime sleepiness, or significant changes in sleep requirements warrant medical attention. The key takeaway is not that an occasional bad night's sleep will irrevocably harm metabolism. Rather, the concern lies in the repetitive pattern where mild sleep deprivation becomes a routine, and its cumulative effects become imperceptible over time. While sleep may appear passive from the outside, internally, it is a sophisticated biological mechanism that regulates hormones, facilitates tissue restoration, maintains alertness, and prepares the body and mind for the demands of the next day. When we consistently shortchange our sleep, the body eventually demands its due, collecting the accumulated debt in ways that impact our overall health.