Lactic acid may play a role in depression-like behaviors caused by blue light during sleep

High-blue-light exposure at night is positively associated with depressive symptoms.

• Animal studies indicate that exposure to blue light during sleep may induce depression-like behaviors.
• Lactic acid levels were found to be relevant to depression through Mendelian randomization analysis.
• Elevated lactic acid levels were observed in the cerebrospinal fluid and lateral habenula of rats exhibiting depression-like behaviors.
• The administration of a lactate inhibitor alleviated depression-like behaviors and affected neuronal function in the lateral habenula.
• The findings suggest potential molecular mechanisms driving depression associated with blue light exposure.

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