Time Change: What Science Just Discovered About Our Internal Clock
Wednesday, November 5 2025 | 14 h 53 min | Vision Science
A team of Montreal-based scientists has uncovered how the brain’s biological clock forms the neural circuits that keep our bodies aligned with the day-night cycle, a breakthrough published in Cell Reports.
Led by Dr. Michel Cayouette of the Montreal Clinical Research Institute (IRCM) and the Université de Montréal, the researchers identified an unexpected player: Müller glial cells in the retina. Once thought to serve a purely structural role, these cells appear essential to the development of neural pathways that synchronize our internal rhythms with the light-dark cycle.
“These results show that the dialogue between nerve cells and their glial partners is crucial for building the system that regulates our circadian rhythms,” said Dr. Cayouette.
How the Retina Helps Keep Time
The study found that Müller glial cells release specific chemical signals that guide light-sensitive neurons in the retina to connect properly with the brain regions that control circadian rhythms. When these signals are missing, neurons become overly reactive, and the biological clock fails to adjust to changes in light exposure.
With most Canadians recently setting their clocks back, the research is timely. Seasonal time shifts are known to disrupt sleep and biological rhythms, often leading to temporary fatigue and mood changes. Understanding how the retina helps the brain adapt to these changes could pave the way for new treatments for circadian rhythm disorders.
Potential for Future Therapies
Disturbances in the circadian system have been linked to conditions such as insomnia, seasonal depression, metabolic imbalance, and even certain cancers. By revealing how these timing circuits form, the study could help researchers develop therapies to prevent or correct such disruptions.
The project, conducted in collaboration with Drs. Nicolas Cermakian and Arjun Krishnaswamy, highlights the intricate cellular communication between the retina and the brain, and how it keeps our internal clock in sync with the world around us.
Source: Université de Montréal – News
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