New Discoveries Connect Brain Structures to Morning and Night Chronotypes

Recent research sheds light on the neurobiological foundations that determine whether someone is a 'morning person' or a 'night owl.' Chronotype, which influences sleep and activity patterns, varies widely among individuals and is linked to both behavioral traits and health outcomes. Societal changes, including the rise of portable devices and streaming services, may have contributed to shifts in these patterns, with late sleepers often facing greater risks of mental health issues like depression and anxiety, as well as physical health problems.

Understanding the brain mechanisms behind chronotype is crucial for developing healthier lifestyle interventions and medical treatments. A comprehensive study conducted by researchers at McGill University and the Mila–Quebec AI Institute analyzed brain imaging data and phenotypic traits from over 27,000 UK Biobank participants. Their findings reveal significant associations between chronotype and specific brain regions, notably the basal ganglia, limbic system, hippocampus, and cerebellum.

The study utilized advanced pattern-learning analysis across multiple brain imaging modalities—gray matter volume, white-matter integrity, and functional connectivity—along with accelerometry data capturing daily movement. Results showed that these brain structures are deeply involved in regulating sleep-wake preferences, emotional regulation, and behavioral tendencies. This research offers one of the most extensive insights into how intrinsic brain differences underpin individual chronotypes.

Le Zhou, Karin Saltoun, and colleagues highlight that night owls tend to adopt less healthy lifestyle habits, are more susceptible to mood disorders, and often have reduced physical fitness compared to early risers. While individual differences in chronotype impact health and behavior, their neurobiological basis remained largely unknown until now. These findings open the door for future studies aimed at targeted therapies and lifestyle recommendations tailored to one's biological predispositions, potentially improving mental health and overall well-being.

Source: https://medicalxpress.com/news/2025-04-insight-neurobiological-roots-morning-person.html