Chinese Study Reveals Link between Exposure to Artificial Light at Night and Depression

Beijing, June 22 (ONA) --- A study from the University of Science and Technology of China, the Kunming Institute of Zoology of the Chinese Academy of Sciences, and the Hefei University of Technology has revealed that exposure to artificial light at night can lead to depression-like behaviors by activating a specific neural pathway in the brain.

The study, conducted on a group of hedgehogs, diurnal mammals closely related to primates, provides insight into how nighttime light can disrupt mood regulation.

The research team exposed hedgehogs to blue light for two hours each night for three weeks. After this exposure, the animals showed clear depression-like symptoms, including a 20 percent decrease in sucrose preference, reduced exploratory behavior, and impaired long-term memory.

Using advanced neural tracing techniques, the researchers identified a previously undiscovered visual circuit. They found specialized retinal neurons sending direct signals to the periaqueductal nucleus, which in turn connects to the nucleus accumbens, a key brain center for regulating mood.

When the periaqueductal nucleus neurons were chemically silenced, hedgehogs did not develop depression-like behaviors in response to light exposure at night. Further analysis through RNA sequencing revealed that these changes coincided with altered activity in genes associated with depression, suggesting potential long-term effects.

"These findings provide us with both a warning and a roadmap," said Yao Yonggang, professor at the Kunming Institute of Zoology. The same light that enables us to be productive at night may be subtly reshaping the brain circuits that control mood—but now we know where to look for solutions, he added.

--- Ends/Khalid